# Tic-tac-toe

Tic-tac-toe
You are encouraged to solve this task according to the task description, using any language you may know.

Play a game of tic-tac-toe. Ensure that legal moves are played and that a winning position is notified.

`with Ada.Text_IO, Ada.Numerics.Discrete_Random;  -- can play human-human, human-computer, computer-human or computer-computer  -- the computer isn't very clever: it just chooses a legal random move procedure Tic_Tac_Toe is    type The_Range is range 1 .. 3;   type Board_Type is array (The_Range, The_Range) of Character;    package Rand is new Ada.Numerics.Discrete_Random(The_Range);   Gen: Rand.Generator; -- required for the random moves    procedure Show_Board(Board: Board_Type) is      use Ada.Text_IO;   begin      for Row in The_Range loop         for Column in The_Range loop            Put(Board(Row, Column));         end loop;         Put_Line("");      end loop;      Put_Line("");   end Show_Board;    function Find_Winner(Board: Board_Type) return Character is      -- if 'x' or 'o' wins, it returns that, else it returns ' '       function Three_Equal(A,B,C: Character) return Boolean is      begin         return (A=B) and (A=C);      end Three_Equal;    begin -- Find_Winner      for I in The_Range loop         if    Three_Equal(Board(I,1), Board(I,2), Board(I,3)) then            return Board(I,1);         elsif  Three_Equal(Board(1,I), Board(2,I), Board(3,I)) then            return Board(1,I);         end if;      end loop;      if Three_Equal(Board(1,1), Board(2,2), Board (3,3)) or         Three_Equal(Board(3,1), Board(2,2), Board (1,3)) then         return Board(2,2);      end if;      return ' ';   end Find_Winner;    procedure Do_Move(Board: in out Board_Type;                     New_Char: Character; Computer_Move: Boolean) is      Done: Boolean := False;      C: Character;      use Ada.Text_IO;       procedure Do_C_Move(Board: in out Board_Type; New_Char: Character) is         Found: Boolean := False;         X,Y: The_Range;      begin         while not Found loop            X := Rand.Random(Gen);            Y := Rand.Random(Gen);            if (Board(X,Y) /= 'x') and  (Board(X,Y) /= 'o') then               Found := True;               Board(X,Y) := New_Char;            end if;         end loop;      end Do_C_Move;    begin      if Computer_Move then         Do_C_Move(Board, New_Char);      else -- read move;         Put_Line("Choose your move, " & New_Char);         while not Done loop            Get(C);            for Row in The_Range loop               for Col in The_Range loop                  if Board(Row, Col) = C then                     Board(Row, Col) := New_Char;                     Done := True;                  end if;               end loop;            end loop;         end loop;      end if;   end Do_Move;    The_Board : Board_Type := (('1','2','3'), ('4','5','6'), ('7','8','9'));   Cnt_Moves: Natural := 0;   Players: array(0 .. 1) of Character := ('x', 'o'); -- 'x' begins   C_Player: array(0 .. 1) of Boolean := (False, False);   Reply: Character; begin -- Tic_Tac_Toe    -- firstly, ask whether the computer shall take over either player   for I in Players'Range loop      Ada.Text_IO.Put_Line("Shall " & Players(I) &                             " be run by the computer? (y=yes)");      Ada.Text_IO.Get(Reply);      if Reply='y' or Reply='Y' then         C_Player(I) := True;         Ada.Text_IO.Put_Line("Yes!");      else         Ada.Text_IO.Put_Line("No!");      end if;   end loop;   Rand.Reset(Gen); -- to initalize the random generator    -- now run the game   while (Find_Winner(The_Board) = ' ') and (Cnt_Moves < 9) loop      Show_Board(The_Board);      Do_Move(The_Board, Players(Cnt_Moves mod 2), C_Player(Cnt_Moves mod 2));      Cnt_Moves := Cnt_Moves + 1;   end loop;   Ada.Text_IO.Put_Line("This is the end!");    -- finally, output the outcome   Show_Board (The_Board);   if Find_Winner(The_Board) = ' ' then      Ada.Text_IO.Put_Line("Draw");   else      Ada.Text_IO.Put_Line("The winner is: " & Find_Winner(The_Board));   end if;end Tic_Tac_Toe;`
Output:
```> ./tic_tac_toe
Shall x be run by the computer? (y=yes)
y
Yes!
Shall o be run by the computer? (y=yes)
n
No!
123
456
789

1x3
456
789

5
1x3
4o6
789

1x3
xo6
789

6
1x3
xoo
789

1xx
xoo
789

1
oxx
xoo
789

oxx
xoo
78x

7
oxx
xoo
o8x

This is the end!
oxx
xoo
oxx

Draw

> ./tic_tac_toe
Shall x be run by the computer? (y=yes)
n
No!
Shall o be run by the computer? (y=yes)
y
Yes!
123
456
789

6
123
45x
789

123
45x
o89

4
123
x5x
o89

123
x5x
o8o

8
123
x5x
oxo

o23
x5x
oxo

5
This is the end!
o23
xxx
oxo

The winner is: x
```

## ALGOL W

The user can play O, X, both or neither. O goes first whether user or computer controlled.

`begin     string(10) board;     % initialise the board                                                   %    procedure initBoard ; board := " 123456789";     % display the board                                                      %    procedure showBoard ;        begin            s_w := 0;            write( board(1//1), "|", board(2//1), "|", board(3//1) );            write( "-+-+-" );            write( board(4//1), "|", board(5//1), "|", board(6//1) );            write( "-+-+-" );            write( board(7//1), "|", board(8//1), "|", board(9//1) )        end showBoard ;     % returns true if board pos is free, false otherwise                     %    logical procedure freeSpace( integer value pos ) ;        ( board(pos//1) >= "1" and board(pos//1) <= "9" );     % check for game over                                                    %    logical procedure gameOver ;        begin            logical noMoves;            noMoves := true;            for i := 1 until 9 do if noMoves then noMoves := not freeSpace( i );            noMoves        end gameOver ;     % makes the specified winning move or blocks it, if it will win          %    logical procedure winOrBlock( integer   value pos1, pos2, pos3                                ; string(1) value searchCharacter                                ; string(1) value playerCharacter                                ) ;        if      board(pos1//1) = searchCharacter            and board(pos2//1) = searchCharacter            and freeSpace( pos3 )        then begin            board(pos3//1) := playerCharacter;            true            end        else if board(pos1//1) = searchCharacter            and freeSpace( pos2 )            and board(pos3//1) = searchCharacter        then begin            board(pos2//1) := playerCharacter;            true            end        else if freeSpace( pos1 )            and board(pos2//1) = searchCharacter            and board(pos3//1) = searchCharacter        then begin            board(pos1//1) := playerCharacter;            true            end        else begin            false        end winOrBlock ;     % makes a winning move or blocks a winning move, if there is one         %    logical procedure makeOrBlockWinningMove( string(1) value searchCharacter                                            ; string(1) value playerCharacter                                            ) ;        (  winOrBlock( 1, 2, 3, searchCharacter, playerCharacter )        or winOrBlock( 4, 5, 6, searchCharacter, playerCharacter )        or winOrBlock( 7, 8, 9, searchCharacter, playerCharacter )        or winOrBlock( 1, 4, 7, searchCharacter, playerCharacter )        or winOrBlock( 2, 5, 8, searchCharacter, playerCharacter )        or winOrBlock( 3, 6, 9, searchCharacter, playerCharacter )        or winOrBlock( 1, 5, 9, searchCharacter, playerCharacter )        or winOrBlock( 3, 5, 7, searchCharacter, playerCharacter )        ) ;     % makes a move when there isn't an obvious winning/blocking move         %    procedure move ( string(1) value playerCharacter ) ;        begin            logical moved;            moved := false;            % try for the centre, a corner or the midle of a line            %            for pos := 5, 1, 3, 7, 9, 2, 4, 6, 8 do begin                if not moved and freeSpace( pos ) then begin                    moved := true;                    board(pos//1) := playerCharacter                end            end        end move ;     % gets a move from the user                                              %    procedure userMove( string(1) value playerCharacter ) ;        begin            integer move;            while                begin                    write( "Please enter the move for ", playerCharacter, " " );                    read( move );                    ( move < 1 or move > 9 or not freeSpace( move ) )                end            do  begin                write( "Invalid move" )            end;            board(move//1) := playerCharacter        end userMove ;     % returns true if the three board positions have the player character,   %    %         false otherwise                                                %    logical procedure same( integer   value pos1, pos2, pos3                          ; string(1) value playerCharacter                          ) ;        (   board(pos1//1) = playerCharacter        and board(pos2//1) = playerCharacter        and board(pos3//1) = playerCharacter        );     % returns true if the player has made a winning move, false otherwise    %    logical procedure playerHasWon( string(1) value playerCharacter ) ;        (  same( 1, 2, 3, playerCharacter )        or same( 4, 5, 6, playerCharacter )        or same( 7, 8, 9, playerCharacter )        or same( 1, 4, 7, playerCharacter )        or same( 2, 5, 8, playerCharacter )        or same( 3, 6, 9, playerCharacter )        or same( 1, 5, 9, playerCharacter )        or same( 3, 5, 7, playerCharacter )        ) ;     % takes a players turn - either automated or user input                  %    procedure turn ( string(1) value playerCharacter, otherCharacter                   ; logical   value playerIsUser                   ) ;        begin            if playerIsUser then userMove( playerCharacter )            else begin                write( playerCharacter, " moves..." );                if  not makeOrBlockWinningMove( playerCharacter, playerCharacter )                and not makeOrBlockWinningMove( otherCharacter,  playerCharacter )                then move( playerCharacter )            end;            showBoard        end turn ;     % asks a question and returns true if the user inputs y/Y,               %    % false otherwise                                                        %    logical procedure yes( string(32) value question ) ;        begin            string(1) answer;            write( question );            read( answer );            answer = "y" or answer = "Y"        end yes ;     % play the game                                                          %    while        begin            string(1)  again;            string(32) gameResult;            logical    oIsUser, xIsUser;             oIsUser := yes( "Do you want to play O? " );            xIsUser := yes( "Do you want to play X? " );             gameResult := "it's a draw";            initBoard;            showBoard;            while not gameOver and not playerHasWon( "O" ) and not playerHasWon( "X" ) do begin                turn( "O", "X", oIsUser );                if playerHasWon( "O" ) then gameResult := "O wins"                else if not gameOver then begin                    turn( "X", "O", xIsUser );                    if playerHasWon( "X" ) then gameResult := "X wins"                end            end ;            write( gameResult );             yes( "Play again? " )        end    do  begin end end.`
Output:
```Do you want to play O?          y
Do you want to play X?          n
1|2|3
-+-+-
4|5|6
-+-+-
7|8|9
Please enter the move for O 5
1|2|3
-+-+-
4|O|6
-+-+-
7|8|9
X moves...
X|2|3
-+-+-
4|O|6
-+-+-
7|8|9
...etc...
Please enter the move for O 8
X|2|O
-+-+-
O|O|X
-+-+-
X|O|9
X moves...
X|X|O
-+-+-
O|O|X
-+-+-
X|O|9
Please enter the move for O 9
X|X|O
-+-+-
O|O|X
-+-+-
X|O|O
it's a draw
Play again?                     n
```

## AppleScript

`property OMask : missing valueproperty XMask : missing valueproperty winningNumbers : {7, 56, 73, 84, 146, 273, 292, 448}property difficulty : missing value repeat   set OMask to 0   set XMask to 0    if button returned of (display dialog "Who should start?" buttons {"I shoud", "CPU"}) = "CPU" then set OMask to npcGet()   set difficulty to button returned of (display dialog "Please choose your difficulty" buttons {"Hard", "Normal"})    repeat       set XMask to XMask + 2 ^ (nGet() - 1)       if winnerForMask(XMask) or OMask + XMask = 511 then exit repeat       set OMask to npcGet()       if winnerForMask(OMask) or OMask + XMask = 511 then exit repeat   end repeat    if winnerForMask(OMask) then       set msg to "CPU Wins!"   else if winnerForMask(XMask) then       set msg to "You WON!!!"   else       set msg to "It's a draw"   end if    display dialog msg & return & return & drawGrid() & return & return & "Do you want to play again?"end repeat on nGet()   set theMessage to "It's your turn Player 1, please fill in the number for X" & return & return & drawGrid()   repeat       set value to text returned of (display dialog theMessage default answer "")       if (offset of value in "123456789") is not 0 then           if not positionIsUsed(value as integer) then exit repeat       end if   end repeat   return value as integerend nGet on npcGet()   --first get the free positions   set freeSpots to {}   repeat with s from 1 to 9       if not positionIsUsed(s) then set end of freeSpots to 2 ^ (s - 1)   end repeat   --second check if 1 move can make the CPU win   repeat with spot in freeSpots       if winnerForMask(OMask + spot) then return OMask + spot   end repeat    if difficulty is "Hard" and OMask is 0 then       if XMask = 1 or XMask = 4 then return 2       if XMask = 64 or XMask = 256 then return 128   end if   --third check if a user can make make it win (defensive) place it on position   repeat with spot in freeSpots       if winnerForMask(XMask + spot) then return OMask + spot   end repeat    --fourth check if CPU can win in two moves   repeat with spot1 in freeSpots       repeat with spot2 in freeSpots           if winnerForMask(OMask + spot1 + spot2) then return OMask + spot2       end repeat   end repeat   --fifth check if player can win in two moves   repeat with spot1 in freeSpots       repeat with spot2 in reverse of freeSpots           if winnerForMask(XMask + spot1 + spot2) then return OMask + spot1       end repeat   end repeat   --at last pick a random spot   if XMask + OMask = 0 and difficulty = "Hard" then return 1    return OMask + (some item of freeSpots)end npcGet on winnerForMask(mask)   repeat with winLine in winningNumbers       if BWAND(winLine, mask) = contents of winLine then return true   end repeat   return falseend winnerForMask on drawGrid()   set grid to ""   repeat with o from 0 to 8       if BWAND(OMask, 2 ^ o) = 2 ^ o then           set grid to grid & "O"       else if BWAND(XMask, 2 ^ o) = 2 ^ o then           set grid to grid & "X"       else           set grid to grid & o + 1       end if       if o is in {2, 5} then set grid to grid & return   end repeat   return gridend drawGrid on positionIsUsed(pos)   return BWAND(OMask + XMask, 2 ^ (pos - 1)) = 2 ^ (pos - 1)end positionIsUsed on BWAND(n1, n2)   set theResult to 0   repeat with o from 0 to 8       if (n1 mod 2) = 1 and (n2 mod 2) = 1 then set theResult to theResult + 2 ^ o       set {n1, n2} to {n1 div 2, n2 div 2}   end repeat   return theResult as integerend BWAND`

## AutoHotkey

This program uses a Gui with 9 buttons. Clicking on one will place an X there, disable the button, and cause the program to go somewhere. It plays logically, trying to win, trying to block, or playing randomly in that order.

`Gui, Add, Button, x12 y12 w30 h30 vB1 gButtonHandler,Gui, Add, Button, x52 y12 w30 h30 vB2 gButtonHandler,Gui, Add, Button, x92 y12 w30 h30 vB3 gButtonHandler,Gui, Add, Button, x12 y52 w30 h30 vB4 gButtonHandler,Gui, Add, Button, x52 y52 w30 h30 vB5 gButtonHandler,Gui, Add, Button, x92 y52 w30 h30 vB6 gButtonHandler,Gui, Add, Button, x12 y92 w30 h30 vB7 gButtonHandler,Gui, Add, Button, x52 y92 w30 h30 vB8 gButtonHandler,Gui, Add, Button, x92 y92 w30 h30 vB9 gButtonHandler,; Generated using SmartGUI Creator 4.0Gui, Show, x127 y87 h150 w141, Tic-Tac-ToeWinning_Moves := "123,456,789,147,258,369,159,357"Return ButtonHandler:    ; Fired whenever the user clicks on an enabled button    Go(A_GuiControl,"X")    GoSub MyMoveReturn MyMove: ; Loops through winning moves. First attempts to win, then to block, then a random move    Went=0    Loop, parse, Winning_Moves,`,    {        Current_Set := A_LoopField        X:=O:=0        Loop, parse, Current_Set        {            GuiControlGet, Char,,Button%A_LoopField%            If ( Char = "O" )                O++            If ( Char = "X" )                X++        }        If ( O = 2 and X = 0 ) or ( X = 2 and O = 0 ){            Finish_Line(Current_Set)            Went = 1            Break ; out of the Winning_Moves Loop to ensure the computer goes only once        }    }    If (!Went)        GoSub RandomMoveReturn Go(Control,chr){    GuiControl,,%Control%, %chr%    GuiControl,Disable,%Control%    GoSub, CheckWin} CheckWin:    Loop, parse, Winning_Moves,`,    {        Current_Set := A_LoopField        X:=O:=0        Loop, parse, Current_Set        {            GuiControlGet, Char,,Button%A_LoopField%            If ( Char = "O" )                O++            If ( Char = "X" )                X++        }        If ( O = 3 ){            Msgbox O Wins!            GoSub DisableAll            Break        }        If ( X = 3 ){            MsgBox X Wins!            GoSub DisableAll            Break        }    }return DisableAll:    Loop, 9        GuiControl, Disable, Button%A_Index%return Finish_Line(Set){ ;   Finish_Line is called when a line exists with 2 of the same character. It goes in the remaining spot, thereby blocking or winning.    Loop, parse, set    {        GuiControlGet, IsEnabled, Enabled, Button%A_LoopField%        Control=Button%A_LoopField%        If IsEnabled            Go(Control,"O")    }} RandomMove:    Loop{        Random, rnd, 1, 9        GuiControlGet, IsEnabled, Enabled, Button%rnd%        If IsEnabled        {            Control=Button%rnd%            Go(Control,"O")            Break        }    }return GuiClose:ExitApp `

## AWK

` # syntax: GAWK -f TIC-TAC-TOE.AWKBEGIN {    move[12] = "3 7 4 6 8"; move[13] = "2 8 6 4 7"; move[14] = "7 3 2 8 6"    move[16] = "8 2 3 7 4"; move[17] = "4 6 8 2 3"; move[18] = "6 4 7 3 2"    move[19] = "8 2 3 7 4"; move[23] = "1 9 6 4 8"; move[24] = "1 9 3 7 8"    move[25] = "8 3 7 4 0"; move[26] = "3 7 1 9 8"; move[27] = "6 4 1 9 8"    move[28] = "1 9 7 3 4"; move[29] = "4 6 3 7 8"; move[35] = "7 4 6 8 2"    move[45] = "6 7 3 2 0"; move[56] = "4 7 3 2 8"; move[57] = "3 2 8 4 6"    move[58] = "2 3 7 4 6"; move[59] = "3 2 8 4 6"    split("7 4 1 8 5 2 9 6 3",rotate)    n = split("253 280 457 254 257 350 452 453 570 590",special)    i = 0    while (i < 9) { s[++i] = " " }    print("")    print("You move first, use the keypad:")    board = "\n7 * 8 * 9\n*********\n4 * 5 * 6\n*********\n1 * 2 * 3\n\n? "    printf(board)}state < 7 {    x = \$0    if (s[x] != " ") {      printf("? ")      next    }    s[x] = "X"    ++state    print("")    if (state > 1) {      for (i=0; i<r; ++i) { x = rotate[x] }    }}state == 1 {    for (r=0; x>2 && x!=5; ++r) { x = rotate[x] }    k = x    if (x == 5) { d = 1 } else { d = 5 }}state == 2 {    c = 5.5 * (k + x) - 4.5 * abs(k - x)    split(move[c],t)    d = t[1]    e = t[2]    f = t[3]    g = t[4]    h = t[5]}state == 3 {    k = x / 2.    c = c * 10    d = f    if (abs(c-350) == 100) {      if (x != 9) { d = 10 - x }      if (int(k) == k) { g = f }      h = 10 - g      if (x+0 == e+0) {        h = g        g = 9      }    }    else if (x+0 != e+0) {      d = e      state = 6    }}state == 4 {    if (x+0 == g+0) {      d = h    }    else {      d = g      state = 6    }    x = 6    for (i=1; i<=n; ++i) {      b = special[i]      if (b == 254) { x = 4 }      if (k+0 == abs(b-c-k)) { state = x }    }}state < 7 {    if (state != 5) {      for (i=0; i<4-r; ++i) { d = rotate[d] }      s[d] = "O"    }    for (b=7; b>0; b-=5) {      printf("%s * %s * %s\n",s[b++],s[b++],s[b])      if (b > 3) { print("*********") }    }    print("")}state < 5 {    printf("? ")}state == 5 {    printf("tie game")    state = 7}state == 6 {    printf("you lost")    state = 7}state == 7 {    printf(", play again? ")    ++state    next}state == 8 {    if (\$1 !~ /^[yY]\$/) { exit(0) }    i = 0    while (i < 9) { s[++i] = " " }    printf(board)    state = 0}function abs(x) { if (x >= 0) { return x } else { return -x } } `

## Bash

Computer is X. Computer randomly goes first. Computer plays a good game, but not a perfect game. It will win when it can and draw when it can not.

It performs a depth-first scan of all following moves. It ignores dumb actions like not winning when either player can.

For each possible move it records if it will win, lose, or something else (like win and draw depending on opponent's move).

If there is a choice of best moves, it picks one at random.

I have not used simple bash code to:

1. keep it under 100 lines;
2. to demonstrate usefulness of bash integers;
3. show-off ANSI ESC sequences;
4. implement recursion in bash;
5. demonstrate conditional and alternate execution using && and || with { ...; };
6. show that you don't always need to use \$ to refer to integer variables;
7. encourage use of [[ ]] instead of [ ] for boolean expressions;
8. provide examples of pattern matching; and
9. encourage use of bash for more interesting tasks.
` #!/bin/bashdeclare -a B=( e e e  e e e  e e e )  # Board function show(){  # show B - underline first 2 rows; highlight position; number empty positoins  local -i p POS=\${1:-9}; local UL BOLD="\e[1m" GREEN="\e[32m" DIM="\e[2m" OFF="\e[m" ULC="\e[4m"  for p in 0 1 2 3 4 5 6 7 8; do    [[ p%3 -eq 0 ]] && printf "  "                             # indent boards    UL=""; [[ p/3 -lt 2 ]] && UL=\$ULC                          # underline first 2 rows    [[ p -eq POS ]]   && printf "\$BOLD\$GREEN"                  # bold and colour for this position    [[ \${B[p]} = e ]] && printf "\$UL\$DIM%d\$OFF" \$p || printf "\$UL%s\$OFF" \${B[p]}  # num or UL    { [[ p%3 -lt 2 ]] && printf "\$UL | \$OFF"; } || printf "\n" # underline vertical bars or NL  done}; function win(){  # win 'X' 3 return true if X wins after move in position 3  local ME=\$1; local -i p=\$2  [[ \${B[p/3*3]} = \$ME && \${B[p/3*3+1]} = \$ME && \${B[p/3*3+2]} = \$ME ]] && return 0  # row  [[ \${B[p]}     = \$ME && \${B[(p+3)%9]} = \$ME && \${B[(p+6)%9]} = \$ME ]] && return 0  # col  [[ \${B[4]} != \$ME ]] && return 1                                                   # don't test diags  [[ p%4 -eq 0 && \${B[0]} = \$ME && \${B[8]} = \$ME ]] && return 0                      # TL - BR diag  [[ p%4 -eq 2 || p -eq 4 ]] && [[ \${B[2]} = \$ME && \${B[6]} = \$ME ]]                 # TR - BL diag}; function bestMove(){  # return best move or 9 if none possible  local ME=\$1 OP=\$2; local -i o s p  local -ia S=( -9 -9 -9  -9 -9 -9  -9 -9 -9 )  # score board  local -a SB                                   # save board  [[ \${B[*]//[!e]} = "" ]] && return 9          # game over  SB=( \${B[*]} )                                # save Board  for p in 0 1 2 3 4 5 6 7 8; do                          # for each board position    [[ \${B[p]} != e ]] && continue                        # skip occupied positions    B[p]=\$ME                                              # occupy position    win \$ME \$p && { S[p]=2; B=( \${SB[*]} ); return \$p; }  # ME wins so this is best move    bestMove \$OP \$ME; o=\$?                                # what will opponent do    [[ o -le 8 ]] && { B[o]=\$OP; win \$OP \$o; s=\$?; }      # opponent can make a legal move    S[p]=\${s:-1}                                          # save result of opponent move    B=( \${SB[*]} )                                        # restore board after each trial run  done  local -i best=-1; local -ia MOV=()  for p in 0 1 2 3 4 5 6 7 8; do                     # find all best moves    [[ S[p] -lt 0 ]] && continue                     # dont bother with occupied positions    [[ S[p] -eq S[best] ]] && { MOV+=(p); best=p; }  # add this move to current list    [[ S[p] -gt S[best] ]] && { MOV=(p); best=p; }   # a better move so scrap list and start again  done  return \${MOV[ RANDOM%\${#MOV[*]} ]}  # pick one at random}; function getMove(){  # getMove from opponent  [[ \$ME = X ]] && { bestMove \$ME \$OP; return \$?; }     # pick X move automatically  read -p "O move: " -n 1; printf "\n"; return \$REPLY   # get opponents move}; function turn(){  # turn starts or continues a game. It is ME's turn  local -i p; local ME=\$1 OP=\$2  getMove; p=\$?; [[ p -gt 8 ]] && { printf "Draw!\n"; show; return 1; }  # no move so a draw  B[p]=\$ME; printf "%s moves %d\n" \$ME \$p                                # mark board  win \$ME \$p && { printf "%s wins!\n" \$ME; show \$p; [[ \$ME = X ]] && return 2; return 0; }  [[ \${B[*]//[!e]} = "" ]] && { printf "Draw!\n"; show; return 1; }      # no move so a draw  show \$p; turn \$OP \$ME                                                  # opponent moves}; printf "Bic Bash Bow\n"show; [[ RANDOM%2 -eq 0 ]] && { turn O X; exit \$?; } || turn X O  `
Output:
(nice ANSI formatting is not shown)
```Bic Bash Bow
0 | 1 | 2
3 | 4 | 5
6 | 7 | 8
X moves 1
0 | X | 2
3 | 4 | 5
6 | 7 | 8
O move: 5
O moves 5
0 | X | 2
3 | 4 | O
6 | 7 | 8
X moves 2
0 | X | X
3 | 4 | O
6 | 7 | 8
O move: 0
O moves 0
O | X | X
3 | 4 | O
6 | 7 | 8
X moves 4
O | X | X
3 | X | O
6 | 7 | 8
O move: 6
O moves 6
O | X | X
3 | X | O
O | 7 | 8
X moves 7
X wins!
O | X | X
3 | X | O
O | X | 8
```

## BASIC

### Microsoft Small Basic

This game has a simple AI.

`place1 = 1place2 = 2place3 = 3place4 = 4place5 = 5place6 = 6place7 = 7place8 = 8place9 = 9symbol1 = "X"symbol2 = "O"reset:TextWindow.Clear()TextWindow.Write(place1 + " ")TextWindow.Write(place2 + " ")TextWindow.WriteLine(place3 + " ")TextWindow.Write(place4 + " ")TextWindow.Write(place5 + " ")TextWindow.WriteLine(place6 + " ")TextWindow.Write(place7 + " ")TextWindow.Write(place8 + " ")TextWindow.WriteLine(place9 + " ")TextWindow.WriteLine("Where would you like to go to (choose a number from 1 to 9 and press enter)?")n = TextWindow.Read()If n = 1 then  If place1 = symbol1 or place1 = symbol2 then    Goto ai  Else    place1 = symbol1  EndIfElseIf n = 2 then  If place2 = symbol1 or place2 = symbol2 then    Goto ai  Else    place2 = symbol1  EndIfElseIf n = 3 then  If place3 = symbol1 or place3 = symbol2 then    Goto ai  Else    place3 = symbol1  EndIfElseIf n = 4 then  If place4 = symbol1 or place4 = symbol2 then    Goto ai  Else    place4 = symbol1  EndIfElseIf n = 5 then  If place5 = symbol1 or place5 = symbol2 then    Goto ai  Else    place5 = symbol1  EndIfElseIf n = 6 then  If place6 = symbol1 or place6 = symbol2 then    Goto ai  Else    place6 = symbol1  EndIfElseIf n = 7 then  If place8 = symbol1 or place7 = symbol2 then    Goto ai  Else    place7 = symbol1  EndIfElseIf n = 8 then  If place8 = symbol1 or place8 = symbol2 then    Goto ai  Else    place8 = symbol1  EndIfElseIf n = 9 then  If place9 = symbol1 or place9 = symbol2 then    Goto ai  Else    place9 = symbol1  EndIfEndIfGoto aiai:n = Math.GetRandomNumber(9)If n = 1 then  If place1 = symbol1 or place1 = symbol2 then    Goto ai  Else    place1 = symbol2  EndIfElseIf n = 2 then  If place2 = symbol1 or place2 = symbol2 then    Goto ai  Else    place2 = symbol2  EndIfElseIf n = 3 then  If place3 = symbol1 or place3 = symbol2 then    Goto ai  Else    place3 = symbol2  EndIfElseIf n = 4 then  If place4 = symbol1 or place4 = symbol2 then    Goto ai  Else    place4 = symbol2  EndIfElseIf n = 5 then  If place5 = symbol1 or place5 = symbol2 then    Goto ai  Else    place5 = symbol2  EndIfElseIf n = 6 then  If place6 = symbol1 or place6 = symbol2 then    Goto ai  Else    place6 = symbol2  EndIfElseIf n = 7 then  If place7 = symbol1 or place7 = symbol2 then    Goto ai  Else    place7 = symbol2  EndIfElseIf n = 8 then  If place8 = symbol1 or place8 = symbol2 then    Goto ai  Else    place8 = symbol2  EndIfElseIf n = 9 then  If place9 = symbol1 or place9 = symbol2 then    Goto ai  Else    place9 = symbol2  EndIfEndIfIf place1 = symbol1 and place2 = symbol1 and place3 = symbol1 or place4 = symbol1 and place5 = symbol1 and place6 = symbol1 or place7 = symbol1 and place8 = symbol1 and place9 = symbol1 or place1 = symbol1 and place4 = symbol1 and place7 = symbol1 or place2 = symbol1 and place5 = symbol1 and place8 = symbol1 or place3 = symbol1 and place6 = symbol1 and place9 = symbol1 or place1 = symbol1 and place5 = symbol1 and place9 = symbol1 or place3 = symbol1 and place5 = symbol1 and place7 = symbol1 then  TextWindow.WriteLine("Player 1 (" + symbol1 + ") wins!")ElseIf place1 = symbol2 and place2 = symbol2 and place3 = symbol2 or place4 = symbol2 and place5 = symbol2 and place6 = symbol2 or place7 = symbol2 and place8 = symbol2 and place9 = symbol2 or place1 = symbol2 and place4 = symbol2 and place7 = symbol2 or place2 = symbol2 and place5 = symbol2 and place8 = symbol2 or place3 = symbol2 and place6 = symbol2 and place9 = symbol2 or place1 = symbol2 and place5 = symbol2 and place8 = symbol2 or place3 = symbol2 and place5 = symbol2 and place7 = symbol2 then  TextWindow.WriteLine("Player 2 (" + symbol2 + ") wins!")Else  Goto resetEndIf`

`  `

## Batch File

This is just a game between two human players.

`@echo offsetlocal enabledelayedexpansion:newgameset a1=1set a2=2set a3=3set a4=4set a5=5set a6=6set a7=7set a8=8set a9=9set ll=Xset /a zz=0:display1clsecho Player: %ll%echo %a7%_%a8%_%a9%echo %a4%_%a5%_%a6%echo %a1%_%a2%_%a3%set /p myt=Where would you like to go (choose a number from 1-9 and press enter)?if !a%myt%! equ %myt% (set a%myt%=%ll%goto check)goto display1:checkset /a zz=%zz%+1if %zz% geq 9 goto newgameif %a7%+%a8%+%a9% equ %ll%+%ll%+%ll% goto winif %a4%+%a5%+%a6% equ %ll%+%ll%+%ll% goto winif %a1%+%a2%+%a3% equ %ll%+%ll%+%ll% goto winif %a7%+%a5%+%a3% equ %ll%+%ll%+%ll% goto winif %a1%+%a5%+%a9% equ %ll%+%ll%+%ll% goto winif %a7%+%a4%+%a1% equ %ll%+%ll%+%ll% goto winif %a8%+%a5%+%a2% equ %ll%+%ll%+%ll% goto winif %a9%+%a6%+%a3% equ %ll%+%ll%+%ll% goto wingoto %ll%:Xset ll=Ogoto display1:Oset ll=Xgoto display1:winecho %ll% wins!pause goto newgame `

This code makes a version of Tic Tac Toe with more features:

`@ECHO OFF:BEGIN    REM Skill level  set sl=  cls  echo                       Tic Tac Toe                                 (Q to quit)  echo.  echo.  echo        Pick your skill level (press a number)  echo.  echo               (1) Children under 6  echo               (2) Average Mental Case  echo               (3) Oversized Ego    CHOICE /c:123q /n > nul  if errorlevel 4 goto end  if errorlevel 3 set sl=3  if errorlevel 3 goto layout  if errorlevel 2 set sl=2  if errorlevel 2 goto layout  set sl=1 :LAYOUT  REM Player turn ("x" or "o")  set pt=  REM Game winner ("x" or "o")  set gw=  REM No moves  set nm=  REM Set to one blank space after equal sign (check with cursor end)  set t1=   set t2=   set t3=   set t4=   set t5=   set t6=   set t7=   set t8=   set t9=  :UPDATE  cls  echo   (S to set skill level)       Tic Tac Toe                         (Q to quit)  echo.  echo                               You are the X player.   echo                    Press the number where you want to put an X.       echo.  echo   Skill level %sl%                    7 8 9   echo                                       4 5 6  echo                                       1 2 3  echo.  echo                                       :   :  echo                                     %t1% : %t2% : %t3%  echo                                   ....:...:....  echo                                     %t4% : %t5% : %t6%  echo                                   ....:...:....  echo                                     %t7% : %t8% : %t9%  echo                                       :   :  if "%gw%"=="x" goto winx2  if "%gw%"=="o" goto wino2  if "%nm%"=="0" goto nomoves :PLAYER  set pt=x  REM Layout is for keypad. Change CHOICE to "/c:123456789sq  /n > nul"  REM for numbers to start at top left (also change user layout above).  CHOICE /c:789456123sq /n > nul  if errorlevel 11 goto end  if errorlevel 10 goto begin  if errorlevel 9 goto 9  if errorlevel 8 goto 8  if errorlevel 7 goto 7  if errorlevel 6 goto 6  if errorlevel 5 goto 5  if errorlevel 4 goto 4  if errorlevel 3 goto 3  if errorlevel 2 goto 2  goto 1 :1    REM Check if "x" or "o" already in square.  if "%t1%"=="x" goto player  if "%t1%"=="o" goto player  set t1=x  goto check:2    if "%t2%"=="x" goto player  if "%t2%"=="o" goto player  set t2=x  goto check:3    if "%t3%"=="x" goto player  if "%t3%"=="o" goto player  set t3=x  goto check:4    if "%t4%"=="x" goto player  if "%t4%"=="o" goto player  set t4=x  goto check:5    if "%t5%"=="x" goto player  if "%t5%"=="o" goto player  set t5=x  goto check:6    if "%t6%"=="x" goto player  if "%t6%"=="o" goto player  set t6=x  goto check:7    if "%t7%"=="x" goto player  if "%t7%"=="o" goto player  set t7=x  goto check:8    if "%t8%"=="x" goto player  if "%t8%"=="o" goto player  set t8=x  goto check:9    if "%t9%"=="x" goto player  if "%t9%"=="o" goto player  set t9=x  goto check :COMPUTER  set pt=o  if "%sl%"=="1" goto skill1   REM (win corner to corner)  if "%t1%"=="o" if "%t3%"=="o" if not "%t2%"=="x" if not "%t2%"=="o" goto c2  if "%t1%"=="o" if "%t9%"=="o" if not "%t5%"=="x" if not "%t5%"=="o" goto c5  if "%t1%"=="o" if "%t7%"=="o" if not "%t4%"=="x" if not "%t4%"=="o" goto c4    if "%t3%"=="o" if "%t7%"=="o" if not "%t5%"=="x" if not "%t5%"=="o" goto c5  if "%t3%"=="o" if "%t9%"=="o" if not "%t6%"=="x" if not "%t6%"=="o" goto c6  if "%t9%"=="o" if "%t7%"=="o" if not "%t8%"=="x" if not "%t8%"=="o" goto c8 REM (win outside middle to outside middle)  if "%t2%"=="o" if "%t8%"=="o" if not "%t5%"=="x" if not "%t5%"=="o" goto c5  if "%t4%"=="o" if "%t6%"=="o" if not "%t5%"=="x" if not "%t5%"=="o" goto c5 REM (win all others)  if "%t1%"=="o" if "%t2%"=="o" if not "%t3%"=="x" if not "%t3%"=="o" goto c3  if "%t1%"=="o" if "%t5%"=="o" if not "%t9%"=="x" if not "%t9%"=="o" goto c9  if "%t1%"=="o" if "%t4%"=="o" if not "%t7%"=="x" if not "%t7%"=="o" goto c7  if "%t2%"=="o" if "%t5%"=="o" if not "%t8%"=="x" if not "%t8%"=="o" goto c8  if "%t3%"=="o" if "%t2%"=="o" if not "%t1%"=="x" if not "%t1%"=="o" goto c1  if "%t3%"=="o" if "%t5%"=="o" if not "%t7%"=="x" if not "%t7%"=="o" goto c7  if "%t3%"=="o" if "%t6%"=="o" if not "%t9%"=="x" if not "%t9%"=="o" goto c9  if "%t4%"=="o" if "%t5%"=="o" if not "%t6%"=="x" if not "%t6%"=="o" goto c6  if "%t6%"=="o" if "%t5%"=="o" if not "%t4%"=="x" if not "%t4%"=="o" goto c4  if "%t7%"=="o" if "%t4%"=="o" if not "%t1%"=="x" if not "%t1%"=="o" goto c1  if "%t7%"=="o" if "%t5%"=="o" if not "%t3%"=="x" if not "%t3%"=="o" goto c3  if "%t7%"=="o" if "%t8%"=="o" if not "%t9%"=="x" if not "%t9%"=="o" goto c9  if "%t8%"=="o" if "%t5%"=="o" if not "%t2%"=="x" if not "%t2%"=="o" goto c2  if "%t9%"=="o" if "%t8%"=="o" if not "%t7%"=="x" if not "%t7%"=="o" goto c7  if "%t9%"=="o" if "%t5%"=="o" if not "%t1%"=="x" if not "%t1%"=="o" goto c1  if "%t9%"=="o" if "%t6%"=="o" if not "%t3%"=="x" if not "%t3%"=="o" goto c3 REM (block general attempts) -----------------------------------------------  if "%t1%"=="x" if "%t2%"=="x" if not "%t3%"=="x" if not "%t3%"=="o" goto c3  if "%t1%"=="x" if "%t5%"=="x" if not "%t9%"=="x" if not "%t9%"=="o" goto c9  if "%t1%"=="x" if "%t4%"=="x" if not "%t7%"=="x" if not "%t7%"=="o" goto c7  if "%t2%"=="x" if "%t5%"=="x" if not "%t8%"=="x" if not "%t8%"=="o" goto c8  if "%t3%"=="x" if "%t2%"=="x" if not "%t1%"=="x" if not "%t1%"=="o" goto c1  if "%t3%"=="x" if "%t5%"=="x" if not "%t7%"=="x" if not "%t7%"=="o" goto c7  if "%t3%"=="x" if "%t6%"=="x" if not "%t9%"=="x" if not "%t9%"=="o" goto c9  if "%t4%"=="x" if "%t5%"=="x" if not "%t6%"=="x" if not "%t6%"=="o" goto c6  if "%t6%"=="x" if "%t5%"=="x" if not "%t4%"=="x" if not "%t4%"=="o" goto c4  if "%t7%"=="x" if "%t4%"=="x" if not "%t1%"=="x" if not "%t1%"=="o" goto c1  if "%t7%"=="x" if "%t5%"=="x" if not "%t3%"=="x" if not "%t3%"=="o" goto c3  if "%t7%"=="x" if "%t8%"=="x" if not "%t9%"=="x" if not "%t9%"=="o" goto c9  if "%t8%"=="x" if "%t5%"=="x" if not "%t2%"=="x" if not "%t2%"=="o" goto c2  if "%t9%"=="x" if "%t8%"=="x" if not "%t7%"=="x" if not "%t7%"=="o" goto c7  if "%t9%"=="x" if "%t5%"=="x" if not "%t1%"=="x" if not "%t1%"=="o" goto c1  if "%t9%"=="x" if "%t6%"=="x" if not "%t3%"=="x" if not "%t3%"=="o" goto c3 REM (block obvious corner to corner)   if "%t1%"=="x" if "%t3%"=="x" if not "%t2%"=="x" if not "%t2%"=="o" goto c2  if "%t1%"=="x" if "%t9%"=="x" if not "%t5%"=="x" if not "%t5%"=="o" goto c5  if "%t1%"=="x" if "%t7%"=="x" if not "%t4%"=="x" if not "%t4%"=="o" goto c4    if "%t3%"=="x" if "%t7%"=="x" if not "%t5%"=="x" if not "%t5%"=="o" goto c5  if "%t3%"=="x" if "%t9%"=="x" if not "%t6%"=="x" if not "%t6%"=="o" goto c6  if "%t9%"=="x" if "%t7%"=="x" if not "%t8%"=="x" if not "%t8%"=="o" goto c8  if "%sl%"=="2" goto skill2 REM (block sneaky corner to corner 2-4, 2-6, etc.)   if "%t2%"=="x" if "%t4%"=="x" if not "%t1%"=="x" if not "%t1%"=="o" goto c1  if "%t2%"=="x" if "%t6%"=="x" if not "%t3%"=="x" if not "%t3%"=="o" goto c3  if "%t8%"=="x" if "%t4%"=="x" if not "%t7%"=="x" if not "%t7%"=="o" goto c7    if "%t8%"=="x" if "%t6%"=="x" if not "%t9%"=="x" if not "%t9%"=="o" goto c9 REM (block offset corner trap 1-8, 1-6, etc.)  if "%t1%"=="x" if "%t6%"=="x" if not "%t8%"=="x" if not "%t8%"=="o" goto c8  if "%t1%"=="x" if "%t8%"=="x" if not "%t6%"=="x" if not "%t6%"=="o" goto c6  if "%t3%"=="x" if "%t8%"=="x" if not "%t4%"=="x" if not "%t4%"=="o" goto c4  if "%t3%"=="x" if "%t4%"=="x" if not "%t8%"=="x" if not "%t8%"=="o" goto c8  if "%t9%"=="x" if "%t4%"=="x" if not "%t2%"=="x" if not "%t2%"=="o" goto c2  if "%t9%"=="x" if "%t2%"=="x" if not "%t4%"=="x" if not "%t4%"=="o" goto c4  if "%t7%"=="x" if "%t2%"=="x" if not "%t6%"=="x" if not "%t6%"=="o" goto c6  if "%t7%"=="x" if "%t6%"=="x" if not "%t2%"=="x" if not "%t2%"=="o" goto c2 :SKILL2 REM (block outside middle to outside middle)  if "%t2%"=="x" if "%t8%"=="x" if not "%t5%"=="x" if not "%t5%"=="o" goto c5  if "%t4%"=="x" if "%t6%"=="x" if not "%t5%"=="x" if not "%t5%"=="o" goto c5 REM (block 3 corner trap)  if "%t1%"=="x" if "%t9%"=="x" if not "%t2%"=="x" if not "%t2%"=="o" goto c2  if "%t3%"=="x" if "%t7%"=="x" if not "%t2%"=="x" if not "%t2%"=="o" goto c2  if "%t1%"=="x" if "%t9%"=="x" if not "%t4%"=="x" if not "%t4%"=="o" goto c4  if "%t3%"=="x" if "%t7%"=="x" if not "%t4%"=="x" if not "%t4%"=="o" goto c4  if "%t1%"=="x" if "%t9%"=="x" if not "%t6%"=="x" if not "%t6%"=="o" goto c6  if "%t3%"=="x" if "%t7%"=="x" if not "%t6%"=="x" if not "%t6%"=="o" goto c6  if "%t1%"=="x" if "%t9%"=="x" if not "%t8%"=="x" if not "%t8%"=="o" goto c8  if "%t3%"=="x" if "%t7%"=="x" if not "%t8%"=="x" if not "%t8%"=="o" goto c8:SKILL1  REM (just take a turn)   if not "%t5%"=="x" if not "%t5%"=="o" goto c5  if not "%t1%"=="x" if not "%t1%"=="o" goto c1  if not "%t3%"=="x" if not "%t3%"=="o" goto c3  if not "%t7%"=="x" if not "%t7%"=="o" goto c7  if not "%t9%"=="x" if not "%t9%"=="o" goto c9  if not "%t2%"=="x" if not "%t2%"=="o" goto c2  if not "%t4%"=="x" if not "%t4%"=="o" goto c4  if not "%t6%"=="x" if not "%t6%"=="o" goto c6  if not "%t8%"=="x" if not "%t8%"=="o" goto c8  set nm=0  goto update :C1    set t1=o  goto check:C2    set t2=o  goto check:C3    set t3=o  goto check:C4    set t4=o  goto check:C5    set t5=o  goto check:C6    set t6=o  goto check:C7    set t7=o  goto check:C8    set t8=o  goto check:C9    set t9=o  goto check :CHECK  if "%t1%"=="x" if "%t2%"=="x" if "%t3%"=="x" goto winx  if "%t4%"=="x" if "%t5%"=="x" if "%t6%"=="x" goto winx  if "%t7%"=="x" if "%t8%"=="x" if "%t9%"=="x" goto winx  if "%t1%"=="x" if "%t4%"=="x" if "%t7%"=="x" goto winx  if "%t2%"=="x" if "%t5%"=="x" if "%t8%"=="x" goto winx  if "%t3%"=="x" if "%t6%"=="x" if "%t9%"=="x" goto winx  if "%t1%"=="x" if "%t5%"=="x" if "%t9%"=="x" goto winx  if "%t3%"=="x" if "%t5%"=="x" if "%t7%"=="x" goto winx  if "%t1%"=="o" if "%t2%"=="o" if "%t3%"=="o" goto wino  if "%t4%"=="o" if "%t5%"=="o" if "%t6%"=="o" goto wino  if "%t7%"=="o" if "%t8%"=="o" if "%t9%"=="o" goto wino  if "%t1%"=="o" if "%t4%"=="o" if "%t7%"=="o" goto wino  if "%t2%"=="o" if "%t5%"=="o" if "%t8%"=="o" goto wino  if "%t3%"=="o" if "%t6%"=="o" if "%t9%"=="o" goto wino  if "%t1%"=="o" if "%t5%"=="o" if "%t9%"=="o" goto wino  if "%t3%"=="o" if "%t5%"=="o" if "%t7%"=="o" goto wino  if "%pt%"=="x" goto computer  if "%pt%"=="o" goto update :WINX  set gw=x  goto update:WINX2  echo   You win!  echo   Play again (Y,N)?  CHOICE /c:ynsq /n > nul  if errorlevel 4 goto end  if errorlevel 3 goto begin  if errorlevel 2 goto end  goto layout :WINO  set gw=o  goto update:WINO2  echo   Sorry, You lose.  echo   Play again (Y,N)?  CHOICE /c:ynsq /n > nul  if errorlevel 4 goto end  if errorlevel 3 goto begin  if errorlevel 2 goto end  goto layout :NOMOVES  echo   There are no more moves left!  echo   Play again (Y,N)?  CHOICE /c:ynsq /n > nul  if errorlevel 4 goto end  if errorlevel 3 goto begin  if errorlevel 2 goto end  goto layout :END  cls  echo Tic Tac Toe  echo.  REM Clear all variables (no spaces after equal sign).  set gw=  set nm=  set sl=  set pt=  set t1=  set t2=  set t3=  set t4=  set t5=  set t6=  set t7=  set t8=  set t9=`

## Befunge

Requires an intepreter with working support for numeric input, which unfortunately excludes most online implementations.

Plays reasonably well, but not perfectly, so can be beaten.

`v123456789 --- >9 >48*,:55+\-0g,1v>9>066+0p076+0p^  ^,," |"_v#%3:- <:,,0537051v>:#,_\$#^5#,5#+<>:#v_55+74 1098709<^+55"---+---+---"0<v52069 04560123 >:!#v_0\1v>\$2-:6%v>8036 +0g\66++0p^   \$_>#%  v#9:-1_ 6/55  vv5!/*88\%*28 ::g0_^>9/#v_ "I",,,5v>5++0p82*/3-:*+\:^v,_@ >"uoY",0+5<v0+66_v#!%2:_55v  >:^:" win!"\1-^ g   >\$>0" :evom ruoY">:#,_\$v>p\*8+ 65_^#!/*88g0** `0\!`9:::<&<^0v   >:!67+0g:!56+0g *+*+0" :evom ">"yM">:#,_\$ :. 1234+++, 789*+ \0^<"a s't"98:*+>:#,_\$@>365*+"ward"48* `
Output:
``` 1 | 2 | 3
---+---+---
4 | 5 | 6
---+---+---
7 | 8 | 9

X | 2 | 3
---+---+---
4 | 5 | 6
---+---+---
7 | 8 | 9

My move: 5

X | 2 | 3
---+---+---
4 | O | 6
---+---+---
7 | 8 | 9

X | X | 3
---+---+---
4 | O | 6
---+---+---
7 | 8 | 9

My move: 3

X | X | O
---+---+---
4 | O | 6
---+---+---
7 | 8 | 9

```

## C

Opening alternates between human and computer. Computer never loses.

`#include <stdio.h>#include <stdlib.h> int b[3][3]; /* board. 0: blank; -1: computer; 1: human */ int check_winner(){	int i;	for (i = 0; i < 3; i++) {		if (b[i][0] && b[i][1] == b[i][0] && b[i][2] == b[i][0])			return b[i][0];		if (b[0][i] && b[1][i] == b[0][i] && b[2][i] == b[0][i])			return b[0][i];	}	if (!b[1][1]) return 0; 	if (b[1][1] == b[0][0] && b[2][2] == b[0][0]) return b[0][0];	if (b[1][1] == b[2][0] && b[0][2] == b[1][1]) return b[1][1]; 	return 0;} void showboard(){	const char *t = "X O";	int i, j;	for (i = 0; i < 3; i++, putchar('\n'))		for (j = 0; j < 3; j++)			printf("%c ", t[ b[i][j] + 1 ]);	printf("-----\n");} #define for_ij for (i = 0; i < 3; i++) for (j = 0; j < 3; j++)int best_i, best_j;int test_move(int val, int depth){	int i, j, score;	int best = -1, changed = 0; 	if ((score = check_winner())) return (score == val) ? 1 : -1; 	for_ij {		if (b[i][j]) continue; 		changed = b[i][j] = val;		score = -test_move(-val, depth + 1);		b[i][j] = 0; 		if (score <= best) continue;		if (!depth) {			best_i = i;			best_j = j;		}		best = score;	} 	return changed ? best : 0;} const char* game(int user){	int i, j, k, move, win = 0;	for_ij b[i][j] = 0; 	printf("Board postions are numbered so:\n1 2 3\n4 5 6\n7 8 9\n");	printf("You have O, I have X.\n\n");	for (k = 0; k < 9; k++, user = !user) {		while(user) {			printf("your move: ");			if (!scanf("%d", &move)) {				scanf("%*s");				continue;			}			if (--move < 0 || move >= 9) continue;			if (b[i = move / 3][j = move % 3]) continue; 			b[i][j] = 1;			break;		}		if (!user) {			if (!k) { /* randomize if computer opens, less boring */				best_i = rand() % 3;				best_j = rand() % 3;			} else				test_move(-1, 0); 			b[best_i][best_j] = -1;			printf("My move: %d\n", best_i * 3 + best_j + 1);		} 		showboard();		if ((win = check_winner())) 			return win == 1 ? "You win.\n\n": "I win.\n\n";	}	return "A draw.\n\n";} int main(){	int first = 0;	while (1) printf("%s", game(first = !first));	return 0;}`

## C++

` #include <windows.h>#include <iostream>#include <string> //--------------------------------------------------------------------------------------------------using namespace std; //--------------------------------------------------------------------------------------------------enum players { Computer, Human, Draw, None };const int iWin[8][3] = { { 0, 1, 2 }, { 3, 4, 5 }, { 6, 7, 8 }, { 0, 3, 6 }, { 1, 4, 7 }, { 2, 5, 8 }, { 0, 4, 8 }, { 2, 4, 6 } }; //--------------------------------------------------------------------------------------------------class ttt{public:    ttt() { _p = rand() % 2; reset(); }     void play()    {	int res = Draw;	while( true )	{	    drawGrid();	    while( true )	    {		if( _p ) getHumanMove();		else getComputerMove(); 		drawGrid(); 		res = checkVictory();		if( res != None ) break; 		++_p %= 2;	    } 	    if( res == Human ) cout << "CONGRATULATIONS HUMAN --- You won!";	    else if( res == Computer ) cout << "NOT SO MUCH A SURPRISE --- I won!";	    else cout << "It's a draw!"; 	    cout << endl << endl; 	    string r;	    cout << "Play again( Y / N )? "; cin >> r;	    if( r != "Y" && r != "y" ) return; 	    ++_p %= 2;	    reset(); 	}    } private:    void reset()     {	for( int x = 0; x < 9; x++ )	    _field[x] = None;    }     void drawGrid()    {	system( "cls" );         COORD c = { 0, 2 };	SetConsoleCursorPosition( GetStdHandle( STD_OUTPUT_HANDLE ), c ); 	cout << " 1 | 2 | 3 " << endl;	cout << "---+---+---" << endl;	cout << " 4 | 5 | 6 " << endl;	cout << "---+---+---" << endl;	cout << " 7 | 8 | 9 " << endl << endl << endl; 	int f = 0;	for( int y = 0; y < 5; y += 2 )	    for( int x = 1; x < 11; x += 4 )	    {		if( _field[f] != None )		{		    COORD c = { x, 2 + y };		    SetConsoleCursorPosition( GetStdHandle( STD_OUTPUT_HANDLE ), c );		    string o = _field[f] == Computer ? "X" : "O";		    cout << o;		}		f++;	    }         c.Y = 9;	SetConsoleCursorPosition( GetStdHandle( STD_OUTPUT_HANDLE ), c );    }     int checkVictory()    {	for( int i = 0; i < 8; i++ )	{	    if( _field[iWin[i][0]] != None &&		_field[iWin[i][0]] == _field[iWin[i][1]] && _field[iWin[i][1]] == _field[iWin[i][2]] )	    {		return _field[iWin[i][0]];	    }	} 	int i = 0;	for( int f = 0; f < 9; f++ )	{	    if( _field[f] != None )		i++;	}	if( i == 9 ) return Draw; 	return None;    }     void getHumanMove()    {	int m;	cout << "Enter your move ( 1 - 9 ) ";	while( true )	{	    m = 0;	    do	    { cin >> m; }	    while( m < 1 && m > 9 ); 	    if( _field[m - 1] != None )		cout << "Invalid move. Try again!" << endl;	    else break;	} 	_field[m - 1] = Human;    }     void getComputerMove()    {	int move = 0; 	do{ move = rand() % 9; }	while( _field[move] != None ); 	for( int i = 0; i < 8; i++ )	{	    int try1 = iWin[i][0], try2 = iWin[i][1], try3 = iWin[i][2]; 	    if( _field[try1] != None && _field[try1] == _field[try2] && _field[try3] == None )	    {		move = try3;		if( _field[try1] == Computer ) break;	    } 	    if( _field[try1] != None && _field[try1] == _field[try3] && _field[try2] == None ) 	    {					move = try2;		if( _field[try1] == Computer ) break;	    } 	    if( _field[try2] != None && _field[try2] == _field[try3] && _field[try1] == None )	    {		move = try1;		if( _field[try2] == Computer ) break;	    }        }	_field[move] = Computer;     }  int _p;int _field[9];};//--------------------------------------------------------------------------------------------------int main( int argc, char* argv[] ){    srand( GetTickCount() );     ttt tic;    tic.play();     return 0;}//-------------------------------------------------------------------------------------------------- `
Output:
Computer plays 'X' and human plays 'O'
``` 1 | 2 | X
---+---+---
X | 5 | 6
---+---+---
7 | O | 9

Enter your move ( 1 - 9 )
```

## C#

This implementation is purposely wordy because Tic-Tac-Toe is often a starting level program.
It tries to show a number of C# code features while still keeping each function small and understandable.

`using System;using System.Collections.Generic;using System.Linq;using System.Text; namespace RosettaTicTacToe{  class Program  {     /*================================================================     *Pieces (players and board)     *================================================================*/    static string[][] Players = new string[][] {       new string[] { "COMPUTER", "X" }, // computer player      new string[] { "HUMAN", "O" }     // human player    };     const int Unplayed = -1;    const int Computer = 0;    const int Human = 1;     // GameBoard holds index into Players[] (0 or 1) or Unplayed (-1) if location not yet taken    static int[] GameBoard = new int[9];     static int[] corners = new int[] { 0, 2, 6, 8 };     static int[][] wins = new int[][] {       new int[] { 0, 1, 2 }, new int[] { 3, 4, 5 }, new int[] { 6, 7, 8 },       new int[] { 0, 3, 6 }, new int[] { 1, 4, 7 }, new int[] { 2, 5, 8 },       new int[] { 0, 4, 8 }, new int[] { 2, 4, 6 } };      /*================================================================     *Main Game Loop (this is what runs/controls the game)     *================================================================*/    static void Main(string[] args)    {      while (true)      {        Console.Clear();        Console.WriteLine("Welcome to Rosetta Code Tic-Tac-Toe for C#.");        initializeGameBoard();        displayGameBoard();        int currentPlayer = rnd.Next(0, 2);  // current player represented by Players[] index of 0 or 1        Console.WriteLine("The first move goes to {0} who is playing {1}s.\n", playerName(currentPlayer), playerToken(currentPlayer));        while (true)        {          int thisMove = getMoveFor(currentPlayer);          if (thisMove == Unplayed)          {            Console.WriteLine("{0}, you've quit the game ... am I that good?", playerName(currentPlayer));            break;          }          playMove(thisMove, currentPlayer);          displayGameBoard();          if (isGameWon())          {            Console.WriteLine("{0} has won the game!", playerName(currentPlayer));            break;          }          else if (isGameTied())          {            Console.WriteLine("Cat game ... we have a tie.");            break;          }          currentPlayer = getNextPlayer(currentPlayer);        }        if (!playAgain())          return;      }    }     /*================================================================     *Move Logic     *================================================================*/    static int getMoveFor(int player)    {      if (player == Human)        return getManualMove(player);      else      {        //int selectedMove = getManualMove(player);        //int selectedMove = getRandomMove(player);        int selectedMove = getSemiRandomMove(player);        //int selectedMove = getBestMove(player);        Console.WriteLine("{0} selects position {1}.", playerName(player), selectedMove + 1);        return selectedMove;      }    }     static int getManualMove(int player)    {      while (true)      {        Console.Write("{0}, enter you move (number): ", playerName(player));        ConsoleKeyInfo keyInfo = Console.ReadKey();        Console.WriteLine();  // keep the display pretty        if (keyInfo.Key == ConsoleKey.Escape)          return Unplayed;        if (keyInfo.Key >= ConsoleKey.D1 && keyInfo.Key <= ConsoleKey.D9)        {          int move = keyInfo.KeyChar - '1';  // convert to between 0..8, a GameBoard index position.          if (GameBoard[move] == Unplayed)            return move;          else            Console.WriteLine("Spot {0} is already taken, please select again.", move + 1);        }        else          Console.WriteLine("Illegal move, please select again.\n");      }    }     static int getRandomMove(int player)    {      int movesLeft = GameBoard.Count(position => position == Unplayed);      int x = rnd.Next(0, movesLeft);      for (int i = 0; i < GameBoard.Length; i++)  // walk board ...      {        if (GameBoard[i] == Unplayed && x < 0)    // until we reach the unplayed move.          return i;        x--;      }      return Unplayed;    }     // plays random if no winning move or needed block.    static int getSemiRandomMove(int player)    {      int posToPlay;      if (checkForWinningMove(player, out posToPlay))        return posToPlay;      if (checkForBlockingMove(player, out posToPlay))        return posToPlay;      return getRandomMove(player);    }     // purposely not implemented (this is the thinking part).    static int getBestMove(int player)    {      return -1;    }     static bool checkForWinningMove(int player, out int posToPlay)    {      posToPlay = Unplayed;      foreach (var line in wins)        if (twoOfThreeMatchPlayer(player, line, out posToPlay))          return true;      return false;    }     static bool checkForBlockingMove(int player, out int posToPlay)    {      posToPlay = Unplayed;      foreach (var line in wins)        if (twoOfThreeMatchPlayer(getNextPlayer(player), line, out posToPlay))          return true;      return false;    }     static bool twoOfThreeMatchPlayer(int player, int[] line, out int posToPlay)    {      int cnt = 0;      posToPlay = int.MinValue;      foreach (int pos in line)      {        if (GameBoard[pos] == player)          cnt++;        else if (GameBoard[pos] == Unplayed)          posToPlay = pos;      }      return cnt == 2 && posToPlay >= 0;    }     static void playMove(int boardPosition, int player)    {      GameBoard[boardPosition] = player;    }     static bool isGameWon()    {      return wins.Any(line => takenBySamePlayer(line[0], line[1], line[2]));    }     static bool takenBySamePlayer(int a, int b, int c)    {      return GameBoard[a] != Unplayed && GameBoard[a] == GameBoard[b] && GameBoard[a] == GameBoard[c];    }     static bool isGameTied()    {      return !GameBoard.Any(spot => spot == Unplayed);    }     /*================================================================     *Misc Methods     *================================================================*/    static Random rnd = new Random();     static void initializeGameBoard()    {      for (int i = 0; i < GameBoard.Length; i++)        GameBoard[i] = Unplayed;    }     static string playerName(int player)    {      return Players[player][0];    }     static string playerToken(int player)    {      return Players[player][1];    }     static int getNextPlayer(int player)    {      return (player + 1) % 2;    }     static void displayGameBoard()    {      Console.WriteLine(" {0} | {1} | {2}", pieceAt(0), pieceAt(1), pieceAt(2));      Console.WriteLine("---|---|---");      Console.WriteLine(" {0} | {1} | {2}", pieceAt(3), pieceAt(4), pieceAt(5));      Console.WriteLine("---|---|---");      Console.WriteLine(" {0} | {1} | {2}", pieceAt(6), pieceAt(7), pieceAt(8));      Console.WriteLine();    }     static string pieceAt(int boardPosition)    {      if (GameBoard[boardPosition] == Unplayed)        return (boardPosition + 1).ToString();  // display 1..9 on board rather than 0..8      return playerToken(GameBoard[boardPosition]);    }     private static bool playAgain()    {      Console.WriteLine("\nDo you want to play again?");      return Console.ReadKey(false).Key == ConsoleKey.Y;    }  } }`
Output:
```Welcome to Rosetta Code Tic-Tac-Toe for C#.
1 | 2 | 3
---|---|---
4 | 5 | 6
---|---|---
7 | 8 | 9

The first move goes to HUMAN who is playing Os.

HUMAN, enter you move (number): 5
1 | 2 | 3
---|---|---
4 | O | 6
---|---|---
7 | 8 | 9

COMPUTER selects position 7.
1 | 2 | 3
---|---|---
4 | O | 6
---|---|---
X | 8 | 9

HUMAN, enter you move (number): 0

HUMAN, enter you move (number): 1
O | 2 | 3
---|---|---
4 | O | 6
---|---|---
X | 8 | 9

COMPUTER selects position 9.
O | 2 | 3
---|---|---
4 | O | 6
---|---|---
X | 8 | X

HUMAN, enter you move (number):```

## Common Lisp

` (defun generate-board ()  (loop repeat 9 collect nil)) (defparameter *straights* '((1 2 3) (4 5 6) (7 8 9) (1 4 7) (2 5 8) (3 6 9) (1 5 9) (3 5 7)))(defparameter *current-player* 'x) (defun get-board-elt (n board)  (nth (1- n) board)) (defun legal-p (n board)  (null (get-board-elt n board))) (defun set-board-elt (n board symbol)  (if (legal-p n board)      (setf (nth (1- n) board) symbol)      (progn (format t "Illegal move. Try again.~&")	     (set-board-elt (read) board symbol)))) (defun list-legal-moves (board)  (loop for i from 1 to (length board)     when (legal-p i board)     collect i)) (defun get-random-element (lst)  (nth (random (length lst)) lst)) (defun multi-non-nil-eq (lst)  (and (notany #'null lst)       (notany #'null (mapcar #'(lambda (x) (eq (car lst) x)) lst))       (car lst))) (defun elements-of-straights (board)  (loop for i in *straights*     collect (loop for j from 0 to 2	   collect (get-board-elt (nth j i) board)))) (defun find-winner (board)  (car (remove-if #'null (mapcar #'multi-non-nil-eq (elements-of-straights board))))) (defun set-player (mark)  (format t "Shall a computer play as ~a? (y/n)~&" mark)  (let ((response (read)))    (cond ((equalp response 'y) t)	  ((equalp response 'n) nil)	  (t (format t "Come again?~&")	     (set-player mark))))) (defun player-move (board symbol)  (format t "~%Player ~a, please input your move.~&" symbol)  (set-board-elt (read) board symbol)  (format t "~%")) (defun computer-move (board symbol)  (let ((move (get-random-element (list-legal-moves board))))    (set-board-elt move board symbol)    (format t "~%computer selects ~a~%~%" move))) (defun computer-move-p (current-player autoplay-x-p autoplay-o-p)  (if (eq current-player 'x)      autoplay-x-p      autoplay-o-p)) (defun perform-turn (current-player board autoplay-x-p autoplay-o-p)  (if (computer-move-p current-player autoplay-x-p autoplay-o-p)      (computer-move board current-player)      (player-move board current-player))) (defun switch-player ()  (if (eq *current-player* 'x)       (setf *current-player* 'o)      (setf *current-player* 'x))) (defun display-board (board)  (loop for i downfrom 2 to 0     do (loop for j from 1 to 3	   initially (format t "|")	   do (format t "~a|" (or (get-board-elt (+ (* 3 i) j) board) (+ (* 3 i) j)))	   finally (format t "~&")))) (defun tic-tac-toe ()  (setf *current-player* 'x)  (let ((board (generate-board))	(autoplay-x-p (set-player 'x))	(autoplay-o-p (set-player 'o)))    (format t "~%")    (loop until (or (find-winner board) (null (list-legal-moves board)))       do (display-board board)             do (perform-turn *current-player* board autoplay-x-p autoplay-o-p)       do (switch-player)       finally (if (find-winner board)		   (format t "The winner is ~a!" (find-winner board))		   (format t "It's a tie."))))) `
Output:
```CL-USER> (tic-tac-toe)
Shall a computer play as X? (y/n)
n
Shall a computer play as O? (y/n)
y

|7|8|9|
|4|5|6|
|1|2|3|

5

|7|8|9|
|4|X|6|
|1|2|3|

computer selects 8

|7|O|9|
|4|X|6|
|1|2|3|

## D

`import std.stdio, std.string, std.algorithm, std.conv, std.random,       std.ascii, std.array, std.range, std.math; struct GameBoard {    dchar[9] board = "123456789";    enum : dchar { human = 'X', computer = 'O' }    enum Game { going, humanWins, computerWins, draw }     const pure nothrow @safe @nogc invariant() {        int nHuman = 0, nComputer = 0;        foreach (immutable i, immutable c; board)            if (c.isDigit)                assert(i == c - '1'); // In correct position?            else {                assert(c == human || c == computer);                (c == human ? nHuman : nComputer)++;            }        assert(abs(nHuman - nComputer) <= 1);    }     string toString() const pure {        return format("%(%-(%s|%)\n-+-+-\n%)", board[].chunks(3));    }     bool isAvailable(in int i) const pure nothrow @safe @nogc {        return i >= 0 && i < 9 && board[i].isDigit;    }     auto availablePositions() const pure nothrow @safe [email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */*/ {        return 9.iota.filter!(i => isAvailable(i));    }     Game winner() const pure nothrow @safe [email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */*/ {        static immutable wins = [[0, 1, 2], [3, 4, 5], [6, 7, 8],                                 [0, 3, 6], [1, 4, 7], [2, 5, 8],                                 [0, 4, 8], [2, 4, 6]];         foreach (immutable win; wins) {            immutable bw0 = board[win[0]];            if (bw0.isDigit)                continue; // Nobody wins on this one.             if (bw0 == board[win[1]] && bw0 == board[win[2]])                return bw0 == GameBoard.human ?                              Game.humanWins :                              Game.computerWins;        }         return availablePositions.empty ? Game.draw: Game.going;    }     bool isFinished() const pure nothrow @safe [email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */*/ {        return winner != Game.going;    }     int computerMove() const // Random move.    out(res) {        assert(res >= 0 && res < 9 && isAvailable(res));    } body {        // return availablePositions.array.choice;        return availablePositions.array[uniform(0, \$)];    }}  GameBoard playGame() {    GameBoard board;    bool playsHuman = true;     while (!board.isFinished) {        board.writeln;         int move;        if (playsHuman) {            do {                writef("Your move (available moves: %s)? ",                       board.availablePositions.map!q{ a + 1 });                readf("%d\n", &move);                move--; // Zero based indexing.                if (move < 0)                    return board;            } while (!board.isAvailable(move));        } else            move = board.computerMove;         assert(board.isAvailable(move));        writefln("\n%s chose %d", playsHuman ? "You" : "I", move + 1);        board.board[move] = playsHuman ? GameBoard.human :                                         GameBoard.computer;        playsHuman = !playsHuman; // Switch player.    }     return board;}  void main() {    "Tic-tac-toe game player.\n".writeln;    immutable outcome = playGame.winner;     final switch (outcome) {        case GameBoard.Game.going:            "Game stopped.".writeln;            break;        case GameBoard.Game.humanWins:            "\nYou win!".writeln;            break;        case GameBoard.Game.computerWins:            "\nI win.".writeln;            break;        case GameBoard.Game.draw:            "\nDraw".writeln;            break;    }}`
Output:
```Tic-tac-toe game player.

1|2|3
-+-+-
4|5|6
-+-+-
7|8|9
Your move (available moves: [1, 2, 3, 4, 5, 6, 7, 8, 9])? 1

You chose 1
X|2|3
-+-+-
4|5|6
-+-+-
7|8|9

I chose 2
X|O|3
-+-+-
4|5|6
-+-+-
7|8|9
Your move (available moves: [3, 4, 5, 6, 7, 8, 9])? 5

You chose 5
X|O|3
-+-+-
4|X|6
-+-+-
7|8|9

I chose 3
X|O|O
-+-+-
4|X|6
-+-+-
7|8|9
Your move (available moves: [4, 6, 7, 8, 9])? 9

You chose 9

You win!```

## Erlang

The program will randomly chose if the computer ("X") or the user ("O") starts. The computer look ahead is only one level. Perhaps the computer might lose?

` -module(tic_tac_toe). -export( [task/0] ). task() -> io:fwrite( "Result: ~p.~n", [turn(player(random:uniform()), board())] ).   board() -> [{X, erlang:integer_to_list(X)} || X <- lists:seq(1, 9)]. board_tuples( Selections, Board ) -> [lists:keyfind(X, 1, Board) || X <- Selections]. computer_move( Player, Board ) ->	[N | _T] = lists:flatten( [X(Player, Board) || X <- [fun computer_move_win/2, fun computer_move_block/2, fun computer_move_middle/2, fun computer_move_random/2]] ),	N. computer_move_block( Player, Board ) ->	computer_move_two_same_player( player(false, Player), Board ). computer_move_middle( _Player, Board ) ->	{5, Y} = lists:keyfind( 5, 1, Board ),	computer_move_middle( is_empty(Y) ). computer_move_middle( true ) -> [5];computer_move_middle( false ) -> []. computer_move_random( _Player, Board ) ->	Ns = [X || {X, Y} <- Board, is_empty(Y)],	[lists:nth( random:uniform(erlang:length(Ns)), Ns )]. computer_move_two_same_player( Player, Board ) ->        Selections = [X || X <- three_in_row_all(), is_two_same_player(Player, X, Board)],	computer_move_two_same_player( Player, Board, Selections ). computer_move_two_same_player( _Player, _Board, [] ) -> [];computer_move_two_same_player( _Player, Board, [Selection | _T] ) -> [X || {X, Y} <- board_tuples(Selection, Board), is_empty(Y)]. computer_move_win( Player, Board ) -> computer_move_two_same_player( Player, Board ). is_empty( Square ) -> Square =< "9". % Do not use < "10". is_finished( Board ) -> is_full( Board ) orelse is_three_in_row( Board ). is_full( Board ) -> [] =:= [X || {X, Y} <- Board, is_empty(Y)]. is_three_in_row( Board ) ->	Fun = fun(Selections) -> is_three_in_row_same_player( board_tuples(Selections, Board) ) end,	lists:any( Fun, three_in_row_all() ). is_three_in_row_same_player( Selected ) -> three_in_row_player( Selected ) =/= no_player. is_two_same_player( Player, Selections, Board ) -> is_two_same_player( Player, [{X, Y} || {X, Y} <- board_tuples(Selections, Board), not is_empty(Y)] ). is_two_same_player( Player, [{_X, Player}, {_Y, Player}] ) -> true;is_two_same_player( _Player, _Selected ) -> false. player( Random ) when Random > 0.5 -> "O";player( _Random ) -> "X". player( true, _Player ) -> finished;player( false, "X" ) -> "O";player( false, "O" ) -> "X". result( Board ) -> result( is_full(Board), Board ). result( true, _Board ) -> draw;result( false, Board ) ->	[Winners] = [Selections || Selections <- three_in_row_all(), three_in_row_player(board_tuples(Selections, Board)) =/= no_player],	"Winner is " ++ three_in_row_player( board_tuples(Winners, Board) ). three_in_row_all() -> three_in_row_horisontal() ++ three_in_row_vertical() ++ three_in_row_diagonal().three_in_row_diagonal() -> [[1,5,9], [3,5,7]].three_in_row_horisontal() -> [[1,2,3], [4,5,6], [7,8,9]].three_in_row_vertical() -> [[1,4,7], [2,5,8], [3,6,9]]. three_in_row_player( [{_X, Player}, {_Y, Player}, {_Z, Player}] ) -> three_in_row_player( not is_empty(Player), Player );three_in_row_player( _Selected ) -> no_player. three_in_row_player( true, Player ) -> Player;three_in_row_player( false, _Player ) -> no_player. turn( finished, Board ) -> result( Board );turn( "X"=Player, Board ) ->    N = computer_move( Player, Board ),    io:fwrite( "Computer, ~p, selected ~p~n", [Player, N] ),    New_board = [{N, Player} | lists:keydelete(N, 1, Board)],    turn( player(is_finished(New_board), Player), New_board );turn( "O"=Player, Board ) ->    [turn_board_write_horisontal(X, Board) || X <- three_in_row_horisontal()],     Ns = [X || {X, Y} <- Board, is_empty(Y)],    Prompt = lists:flatten( io_lib:format("Player, ~p, select one of ~p: ", [Player, Ns]) ),    N = turn_next_move( Prompt, Ns ),    New_board = [{N, Player} | lists:keydelete(N, 1, Board)],     turn( player(is_finished(New_board), Player), New_board ). turn_board_write_horisontal( Selections, Board ) ->	Tuples = [lists:keyfind(X, 1, Board) || X <- Selections],	[io:fwrite( "~p ", [Y]) || {_X, Y} <- Tuples],	io:fwrite( "~n" ). turn_next_move( Prompt, Ns ) ->	{ok,[N]} = io:fread( Prompt, "~d" ),	turn_next_move_ok( lists:member(N, Ns), Prompt, Ns, N ). turn_next_move_ok( true, _Prompt, _Ns, N ) -> N;turn_next_move_ok( false, Prompt, Ns, _N ) -> turn_next_move( Prompt, Ns ). `
Output:
```96> tic_tac_toe:task().
"1" "2" "3"
"4" "5" "6"
"7" "8" "9"
Player, "O", select one of [1,2,3,4,5,6,7,8,9]: 5
Computer, "X", selected 2
"1" "X" "3"
"4" "O" "6"
"7" "8" "9"
Player, "O", select one of [1,3,4,6,7,8,9]: 1
Computer, "X", selected 9
"O" "X" "3"
"4" "O" "6"
"7" "8" "X"
Player, "O", select one of [3,4,6,7,8]: 3
Computer, "X", selected 7
"O" "X" "O"
"4" "O" "6"
"X" "8" "X"
Player, "O", select one of [4,6,8]: 8
Computer, "X", selected 6
"O" "X" "O"
"4" "O" "X"
"X" "O" "X"
Player, "O", select one of [4]: 4
Result: draw.
```

## ERRE

Taken from ERRE distribution disk: comments and messages are in Italian.

```!--------------------------------------------
! TRIS.R : gioca a tris contro l'operatore
!--------------------------------------------

PROGRAM TRIS

DIM TRIS%[9],T1%[9],PIECES\$[3]

!\$SEGMENT=\$B800

!\$INCLUDE="PC.LIB"

PROCEDURE DELAY(COUNT%)
FOR Z%=1 TO COUNT DO
END FOR
END PROCEDURE

PROCEDURE SET_BOARD
!
! Disegna lo schema del gioco
!
CLS
!\$KEY
END PROCEDURE

PROCEDURE PUT_PIECES
!
! Pone i pezzi sulla scacchiera
!
Z%=0
FOR ROW%=6 TO 12 STEP 3 DO     ! posizioni assolute sullo schermo
FOR COL%=32 TO 48 STEP 8 DO
LOCATE(ROW%+1,COL%+1)
Z%=Z%+1
PRINT(PIECES\$[TRIS%[Z%]])
END FOR
END FOR
END PROCEDURE

PROCEDURE COMPUTE_MOVE(A%)
CASE A% OF
2-> C1%=C1%+1            END ->
4-> C2%=C2%+1            END ->
8-> S1%=TRUE  S2%=TRUE   END ->
3-> N1%=N1%+1            END ->
9-> N2%=N2%+1            END ->
27-> S1%=FALSE S2%=FALSE  END ->
END CASE
END PROCEDURE

PROCEDURE PREPAREMOVE(T1%[],I%->M%)
!
! Prepara la mossa del calcolatore
!
T1%[I%]=2
C1%=0
C2%=0
N1%=0
N2%=0
FOR K%=0 TO 2 DO
COMPUTE_MOVE(T1%[3*K%+1]*T1%[3*K%+2]*T1%[3*K%+3])
COMPUTE_MOVE(T1%[K%+1]*T1%[K%+4]*T1%[K%+7])
END FOR
COMPUTE_MOVE(T1%[1]*T1%[5]*T1%[9])
COMPUTE_MOVE(T1%[3]*T1%[5]*T1%[7])
M%=-63*N2%+31*C2%-15*N1%+7*C1%
END PROCEDURE

PROCEDURE COMPUTER_MOVE
!
! Coordina le mosse del calcolatore
!
MAXSCORE%=-1000
FOR I%=1 TO 9 DO
IF TRIS%[I%]=1
THEN
PREPAREMOVE(TRIS%[],I%->MV%)
EXIT IF S2% AND NOT S1%
IF S1% AND S2%
THEN
TRIS%[I%]=2
DIARY\$=DIARY\$+"c"+MID\$(STR\$(I%),2)+"*"
PUT_PIECES
EXIT
END IF
IF MV%=0
THEN
MOVE%=I%
EXIT
END IF
IF MV%>MAXSCORE%
THEN
MOVE%=I%
MAXSCORE%=MV%
END IF
END IF
END FOR
IF NOT S2%
THEN
TRIS%[MOVE%]=2
DIARY\$=DIARY\$+"c"+MID\$(STR\$(MOVE%),2)+";"
PUT_PIECES
NMOVE%=NMOVE%-1
S1%=(NMOVE%=0)
END IF
END PROCEDURE

PROCEDURE PLAYER_MOVE
!
! Gioca l'avversario umano usando i tasti cursore per lo spostamento
!
LOCATE(19,13)
PRINT("Tocca a te ....                  ")
REPEAT
ROW%=7
COL%=32
LOCATE(ROW%+1,COL%+1)
PRINT("Ü")
REPEAT
GET(B\$)
IF LEN(B\$)=2 THEN
CASE ASC(RIGHT\$(B\$,1)+CHR\$(0)) OF
77-> ! codice tastiera per CRSR =>
LOCATE(ROW%+1,COL%+1)
PRINT(" ")
COL%=-(COL%+8)*(COL%<=40)-32*(COL%>40)
LOCATE(ROW%+1,COL%+1)
PRINT("Ü")
END ->
75-> ! codice tastiera per CRSR <=
LOCATE(ROW%+1,COL%+1)
PRINT(" ")
COL%=-(COL%-8)*(COL%>=40)-48*(COL%<40)
LOCATE(ROW%+1,COL%+1)
PRINT("Ü")
END ->
80-> ! codice tastiera per CRSR DOWN
LOCATE(ROW%+1,COL%+1)
PRINT(" ")
ROW%=-(ROW%+3)*(ROW%<=10)-7*(ROW%>10)
LOCATE(ROW%+1,COL%+1)
PRINT("Ü")
END ->
72-> ! codice tastiera per CRSR UP
LOCATE(ROW%+1,COL%+1)
PRINT(" ")
ROW%=-(ROW%-3)*(ROW%>=10)-13*(ROW%<10)
LOCATE(ROW%+1,COL%+1)
PRINT("Ü")
END ->
END CASE
END IF
UNTIL B\$=CHR\$(13)
MM%=ROW%+COL%/8-10 ! da coordinate schermo a coordinate scacchiera
UNTIL TRIS%[MM%]=1
TRIS%[MM%]=3
LOCATE(ROW%+1,COL%+1)
PRINT(" ")
DIARY\$=DIARY\$+"p"+MID\$(STR\$(MM%),2)+";"
PUT_PIECES
NMOVE%=NMOVE%-1
S1%=(NMOVE%=0)
LOCATE(19,13)
PRINT(STRING\$(45," "))
END PROCEDURE

BEGIN
DATA(" ","+","o")
SET_BOARD
REPEAT
S1%=FALSE    S2%=FALSE   ! determinano lo stato della partita
NMOVE%=9
FOR Z%=1 TO 3 DO
END FOR
FOR Z%=1 TO 9 DO
TRIS%[Z%]=1
END FOR
LOCATE(19,13)
PRINT("Giochi per primo ?")
REPEAT
GET(A\$)
UNTIL A\$="S" OR A\$="s" OR A\$="N" OR A\$="n"
PUT_PIECES
FOR INDICE%=1 TO 9 DO
IF A\$="s" OR A\$="S"
THEN
PLAYER_MOVE
EXIT IF S1% OR S2%
COMPUTER_MOVE
EXIT IF S1% OR S2%
ELSE
COMPUTER_MOVE
EXIT IF S1% OR S2%
PLAYER_MOVE
EXIT IF S1% OR S2%
END IF
END FOR
LOCATE(19,13)
CASE TRUE OF
(S1% AND NOT S2%)->
PRINT("E' finita pari !!!     ")
END ->
(S2% AND NOT S1%)->
PRINT("HAI VINTO !!!          ")
END ->
(S1% AND S2%)->
PRINT("HO VINTO IO !!!        ")
END ->
END CASE
DELAY(500)
LOCATE(19,13)
PRINT(DIARY\$)
DELAY(500)
LOCATE(19,13)
PRINT("Vuoi giocare ancora ?       ")
REPEAT
GET(A\$)
UNTIL A\$="S" OR A\$="s" OR A\$="N" OR A\$="n"
UNTIL A\$="N" OR A\$="n"
END PROGRAM
```
Output:

A game example

``` ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
░░▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒░░
░░▒▒▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▒▒░░
░░▒▒▓▓                                                                  ▓▓▒▒░░
░░▒▒▓▓ ┌───────────────┐   ╔═══════╤═══════╤═══════╗   ┌────────────┐   ▓▓▒▒░░
░░▒▒▓▓ │───── TRIS ────│   ║   +   │   o   │   +   ║   │Il calcola- │   ▓▓▒▒░░
░░▒▒▓▓ │               │   ║       │       │       ║   │tore non può│   ▓▓▒▒░░
░░▒▒▓▓ │Si gioca contro│   ╟───────┼───────┼───────╢   │perdere e   │   ▓▓▒▒░░
░░▒▒▓▓ │il calcolatore.│   ║   +   │   o   │   o   ║   │perciò il   │   ▓▓▒▒░░
░░▒▒▓▓ │Per muoversi   │   ║       │       │       ║   │giocatore   │   ▓▓▒▒░░
░░▒▒▓▓ │usare i tasti  │   ╟───────┼───────┼───────╢   │può al mas- │   ▓▓▒▒░░
░░▒▒▓▓ │cursore e ◄──┘ │   ║   o   │   +   │   o   ║   │simo pareg- │   ▓▓▒▒░░
░░▒▒▓▓ │per confermare.│   ║       │       │       ║   │giare.      │   ▓▓▒▒░░
░░▒▒▓▓ └───────────────┘   ╚═══════╧═══════╧═══════╝   └────────────┘   ▓▓▒▒░░
░░▒▒▓▓                                                                  ▓▓▒▒░░
░░▒▒▓▓                                                                  ▓▓▒▒░░
░░▒▒▓▓  ┌────────────────────────────────────────────────────────────┐  ▓▓▒▒░░
░░▒▒▓▓  │  Vuoi giocare ancora ?                                     │  ▓▓▒▒░░
░░▒▒▓▓  └────────────────────────────────────────────────────────────┘  ▓▓▒▒░░
░░▒▒▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▒▒░░
░░▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒░░
░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
```

## Euphoria

Works with: OpenEuphoria

No computer AI

` include std/console.einclude std/text.einclude std/search.einclude std/sequence.e sequence board sequence players = {"X","O"} function DisplayBoard()	for i = 1 to 3 do		for j = 1 to 3 do			printf(1,"%s",board[i][j])			if j < 3 then				printf(1,"%s","|")			end if		end for		if i < 3 then			puts(1,"\n-----\n")		else			puts(1,"\n\n")		end if	end for 	return 1end function function CheckWinner()sequence temp = board	for a = 1 to 2 do		for i = 1 to 3 do			if equal({"X","X","X"},temp[i]) then				puts(1,"X wins\n\n")				return 1			elsif equal({"O","O","O"},temp[i]) then				puts(1,"O wins\n\n")				return 1			end if		end for		temp = columnize(board)	end for	if equal({"X","X","X"},{board[1][1],board[2][2],board[3][3]}) or	   equal({"X","X","X"},{board[1][3],board[2][2],board[3][1]}) then		puts(1,"X wins\n")		return 1	elsif equal({"O","O","O"},{board[1][1],board[2][2],board[3][3]}) or	   equal({"O","O","O"},{board[1][3],board[2][2],board[3][1]}) then		puts(1,"O wins\n")		return 1	end if	 	if moves = 9 then		puts(1,"Draw\n\n")		return 1	end if 	return 0end function integer turn, row, column, movessequence replaywhile 1 do	board = repeat(repeat(" ",3),3)	DisplayBoard()	turn = rand(2)	moves = 0 	while 1 do		while 1 do			printf(1,"%s's turn\n",players[turn])			row = prompt_number("Enter row: ",{})			column = prompt_number("Enter column: ",{})			if match(board[row][column]," ") then				board[row][column] = players[turn]				moves += 1				exit			else				puts(1,"Space already taken - pick again\n")			end if		end while 		DisplayBoard() 		if CheckWinner() then			exit		end if 		if turn = 1 then			turn = 2		else			turn = 1		end if	end while 	replay = lower(prompt_string("Play again (y/n)?\n\n")) 	if match(replay,"n") then		exit	end if end while `
Output:
``` | |
-----
| |
-----
| |

O's turn
Enter row: 1
Enter column: 1
O| |
-----
| |
-----
| |

X's turn
Enter row: 3
Enter column: 3
O| |
-----
| |
-----
| |X

O's turn
Enter row: 3
Enter column: 1
O| |
-----
| |
-----
O| |X

X's turn
Enter row: 2
Enter column: 1
O| |
-----
X| |
-----
O| |X

O's turn
Enter row: 2
Enter column: 2
O| |
-----
X|O|
-----
O| |X

X's turn
Enter row: 1
Enter column: 3
O| |X
-----
X|O|
-----
O| |X

O's turn
Enter row: 1
Enter column: 2
O|O|X
-----
X|O|
-----
O| |X

X's turn
Enter row: 3
Enter column: 2
O|O|X
-----
X|O|
-----
O|X|X

O's turn
Enter row: 2
Enter column: 3
O|O|X
-----
X|O|O
-----
O|X|X

Draw

Play again (y/n)?
```

## F#

A purely-functional solution with a naive (but perfect) computer player implementation. The first move is played randomly by the computer.

`type Brick = | Empty | Computer | User let brickToString = function | Empty -> ' ' | Computer -> 'X' | User -> 'O' // y -> x -> Bricktype Board = Map<int, Map<int, Brick> > let emptyBoard =  let emptyRow = Map.ofList [0,Empty; 1,Empty; 2,Empty]  Map.ofList [0,emptyRow; 1,emptyRow; 2,emptyRow] let get (b:Board) (x,y) = b.[y].[x] let set player (b:Board) (x,y) : Board =  let row = b.[y].Add(x, player)  b.Add(y, row) let winningPositions =   [for x in [0..2] -> x,x] // first diagonal  ::[for x in [0..2] -> 2-x,x] // second diagonal  ::[for y in [0..2] do     yield! [[for x in [0..2]->(y,x)]; // columns             [for x in [0..2] -> (x,y)]]] // rows let hasWon player board =   List.exists    (fun ps -> List.forall (fun pos -> get board pos = player) ps)    winningPositions let freeSpace board =  [for x in 0..2 do     for y in 0..2 do       if get board (x,y) = Empty then yield x,y] type Evaluation = | Win | Draw | Lose let rec evaluate board move =  let b2 = set Computer board move  if hasWon Computer b2 then Win  else    match freeSpace b2 with    | [] -> Draw    | userChoices ->        let b3s = List.map (set User b2) userChoices       if List.exists (hasWon User) b3s then Lose       elif List.exists (fun b3 -> bestOutcome b3 = Lose) b3s       then Lose       elif List.exists (fun b3 -> bestOutcome b3 = Draw) b3s       then Draw       else Win and findBestChoice b =  match freeSpace b with  | [] -> ((-1,-1), Draw)  | choices ->     match List.tryFind (fun c -> evaluate b c = Win) choices with    | Some c -> (c, Win)    | None -> match List.tryFind (fun c -> evaluate b c = Draw) choices with              | Some c -> (c, Draw)              | None -> (List.head choices, Lose) and bestOutcome b = snd (findBestChoice b) let bestChoice b = fst (findBestChoice b) let computerPlay b = set Computer b (bestChoice b) let printBoard b =  printfn "   | A | B | C |"  printfn "---+---+---+---+"  for y in 0..2 do   printfn " %d | %c | %c | %c |"    (3-y)    (get b (0,y) |> brickToString)    (get b (1,y) |> brickToString)    (get b (2,y) |> brickToString)   printfn "---+---+---+---+" let rec userPlay b =  printfn "Which field do you play? (format: a1)"  let input = System.Console.ReadLine()  if input.Length <> 2     || input.[0] < 'a' || input.[0] > 'c'     || input.[1] < '1' || input.[1] > '3' then     printfn "illegal input"     userPlay b  else     let x = int(input.[0]) - int('a')     let y = 2 - int(input.[1]) + int('1')     if get b (x,y) <> Empty then       printfn "Field is not free."       userPlay b     else       set User b (x,y) let rec gameLoop b player =  if freeSpace b = [] then    printfn "Game over. Draw."  elif player = Computer then    printfn "Computer plays..."    let b2 = computerPlay b    printBoard b2    if hasWon Computer b2 then      printfn "Game over. I have won."    else      gameLoop b2 User  elif player = User then    let b2 = userPlay b    printBoard b2    if hasWon User b2 then      printfn "Game over. You have won."    else      gameLoop b2 Computer // randomly choose an element of a listlet choose =  let rnd = new System.Random()  fun (xs:_ list) -> xs.[rnd.Next(xs.Length)] // play first brick randomlyprintfn "Computer starts."let b = set Computer emptyBoard (choose (freeSpace emptyBoard))printBoard bgameLoop b User`

Example game:

```Computer starts.
| A | B | C |
---+---+---+---+
3 |   |   | X |
---+---+---+---+
2 |   |   |   |
---+---+---+---+
1 |   |   |   |
---+---+---+---+
Which field do you play? (format: a1)
a1
| A | B | C |
---+---+---+---+
3 |   |   | X |
---+---+---+---+
2 |   |   |   |
---+---+---+---+
1 | O |   |   |
---+---+---+---+
Computer plays...
| A | B | C |
---+---+---+---+
3 | X |   | X |
---+---+---+---+
2 |   |   |   |
---+---+---+---+
1 | O |   |   |
---+---+---+---+
Which field do you play? (format: a1)
b3
| A | B | C |
---+---+---+---+
3 | X | O | X |
---+---+---+---+
2 |   |   |   |
---+---+---+---+
1 | O |   |   |
---+---+---+---+
Computer plays...
| A | B | C |
---+---+---+---+
3 | X | O | X |
---+---+---+---+
2 |   |   |   |
---+---+---+---+
1 | O |   | X |
---+---+---+---+
Which field do you play? (format: a1)
c2
| A | B | C |
---+---+---+---+
3 | X | O | X |
---+---+---+---+
2 |   |   | O |
---+---+---+---+
1 | O |   | X |
---+---+---+---+
Computer plays...
| A | B | C |
---+---+---+---+
3 | X | O | X |
---+---+---+---+
2 |   | X | O |
---+---+---+---+
1 | O |   | X |
---+---+---+---+
Game over. I have won.
```

## Go

Intermediate, like Python's "Better skilled player." Computer wins and blocks where it can, but otherwise plays randomly. Plays multiple games and keeps score. Player gets first move of first game. Afterwards, loser gets to go first, or after cat games, first move alternates.

`package main import (    "bufio"    "fmt"    "math/rand"    "os"    "strings") var b []byte func printBoard() {    fmt.Printf("%s\n%s\n%s\n", b[0:3], b[3:6], b[6:9])} var pScore, cScore intvar pMark, cMark byte = 'X', 'O'var in = bufio.NewReader(os.Stdin) func main() {    b = make([]byte, 9)    fmt.Println("Play by entering a digit.")    for {        // start of game        for i := range b {            b[i] = '1' + byte(i)        }        computerStart := cMark == 'X'        if computerStart {            fmt.Println("I go first, playing X's")        } else {            fmt.Println("You go first, playing X's")        }    TakeTurns:        for {            if !computerStart {                if !playerTurn() {                    return                }                if gameOver() {                    break TakeTurns                }             }            computerStart = false            computerTurn()            if gameOver() {                break TakeTurns            }        }        fmt.Println("Score: you", pScore, "me", cScore)        fmt.Println("\nLet's play again.")    }} func playerTurn() bool {    var pm string    var err error    for i := 0; i < 3; i++ { // retry loop        printBoard()        fmt.Printf("%c's move? ", pMark)        if pm, err = in.ReadString('\n'); err != nil {            fmt.Println(err)            return false        }        pm = strings.TrimSpace(pm)        if pm >= "1" && pm <= "9" && b[pm[0]-'1'] == pm[0] {            x := pm[0] - '1'            b[x] = pMark            return true        }    }    fmt.Println("You're not playing right.")    return false} var choices = make([]int, 9) func computerTurn() {    printBoard()    var x int    defer func() {        fmt.Println("My move:", x+1)        b[x] = cMark    }()    // look for two in a row    block := -1    for _, l := range lines {        var mine, yours int        x = -1        for _, sq := range l {            switch b[sq] {            case cMark:                mine++            case pMark:                yours++            default:                x = sq            }        }        if mine == 2 && x >= 0 {            return // strategy 1: make winning move        }        if yours == 2 && x >= 0 {            block = x        }     }    if block >= 0 {        x = block // strategy 2: make blocking move        return    }    // default strategy: random move    choices = choices[:0]    for i, sq := range b {         if sq == '1'+byte(i) {            choices = append(choices, i)        }    }    x = choices[rand.Intn(len(choices))]}    func gameOver() bool {    // check for win    for _, l := range lines {        if b[l[0]] == b[l[1]] && b[l[1]] == b[l[2]] {            printBoard()            if b[l[0]] == cMark {                fmt.Println("I win!")                cScore++                pMark, cMark = 'X', 'O'            } else {                fmt.Println("You win!")                pScore++                pMark, cMark = 'O', 'X'            }            return true         }     }    // check for empty squares    for i, sq := range b {        if sq == '1'+byte(i) {            return false        }    }    fmt.Println("Cat game.")    pMark, cMark = cMark, pMark    return true} var lines = [][]int{    {0, 1, 2}, // rows    {3, 4, 5},    {6, 7, 8},    {0, 3, 6}, // columns    {1, 4, 7},    {2, 5, 8},    {0, 4, 8}, // diagonals    {2, 4, 6},}`

## Groovy

Simplified version of Tic Tac Toe for player vs. player (no AI computer-controlled option).

`class Main { 	def input = new Scanner(System.in) 	static main(args) {		Main main = new Main();		main.play();	} 	public void play() { 		TicTackToe game = new TicTackToe();		game.init()		def gameOver = false				def player = game.player1 		println "Players take turns marking a square. Only squares \n"+				"not already marked can be picked. Once a player has \n"+    			"marked three squares in a row, column or diagonal, they win! If all squares \n"+    			"are marked and no three squares are the same, a tied game is declared.\n"+				"Player 1 is O and Player 2 is X \n"+    			"Have Fun! \n\n"		println "\${game.drawBoard()}" 		while (!gameOver && game.plays < 9) { 			player = game.currentPlayer == 1 ? game.player1 :game.player2			def validPick = false;			while (!validPick) { 				def square				println "Next \$player, enter move by selecting square's number :"					try {					square = input.nextLine();				} catch (Exception ex) { }					 				if (square.length() == 1 && Character.isDigit(square.toCharArray()[0])) {	validPick = game.placeMarker(square)	}				if (!validPick) {	println "Select another Square"	} 			} 			(game.checkWinner(player))?	gameOver = true	: game.switchPlayers()						println(game.drawBoard());	 		}				println "Game Over, " + ((gameOver == true)? "\$player Wins" : "Draw")	} } public class TicTackToe {     def board = new Object[3][3]	def final player1 = "player 1"	def final player2 = "player 2"	def final marker1 = 'X'	def final marker2 = 'O'     int currentPlayer	int plays 	public TicTacToe(){ 	}      def init() {        int counter = 0;       (0..2).each { row ->           (0..2).each { col ->                board[row][col] = (++counter).toString();            }        }	   plays = 0	   currentPlayer =1    }     def switchPlayers() {        currentPlayer = (currentPlayer == 1) ? 2:1        plays++    }     def placeMarker(play) {		def result = false        (0..2).each { row ->            (0..2).each { col ->                if (board[row][col].toString()==play.toString()){                    board[row][col] = (currentPlayer == 1) ? marker2 : marker1;                    result =  true;                }            }        }        return result;    }     def checkWinner(player) {    	char current = (player == player1)? marker2:  marker1        //Checking         return checkRows(current) || checkColumns(current) ||checkDiagonals(current);    }     def checkRows(char current){		(0..2).any{ line ->			  board[line].every { it == current}		}    }      def checkColumns(char current){						(0..2).any{i ->			(0..2).every{j ->				 board[j][i]==current }				}    }     def checkDiagonals(char current){		def rightDiag = [board[0][0],board[1][1],board[2][2]]		def leftDiag =  [board[0][2],board[1][1],board[2][0]]		return rightDiag.every{it == current} || leftDiag.every{it == current}    }      def drawBoard() {        StringBuilder builder = new StringBuilder("Game board: \n");        (0..2).each { row->            (0..2).each {col ->                builder.append("[" + board[row][col] + "]");            }            builder.append("\n");        }        builder.append("\n");        return builder.toString();    }}`

Computer player has three strategies: 1. Try to block the opponent first, 2. Try to guess a good position for the next move, 3. Place a piece randomly. There are lots of comments throughout the code.

` module Main where import System.Randomimport Data.List (intercalate, find, minimumBy)import System.Environment (getArgs)import Data.Char (digitToInt)import Data.Maybe (listToMaybe, mapMaybe)import Control.Monad (guard)import Data.Ord (comparing) -- check if there is a horizontal, vertical or diagonal line of-- X or Otictactoe :: String -> Booltictactoe a = tictactoeFor 'X' a /= tictactoeFor 'O' a -- check if there is a horizontal, vertical or diagonal line-- for the given player "n"tictactoeFor :: Char -> String -> BooltictactoeFor n [a,b,c,d,e,f,g,h,i] =    [n,n,n] `elem` [[a,b,c],[d,e,f],[g,h,i],[a,d,g],                    [b,e,h],[c,f,i],[a,e,i],[c,e,g]] -- empty game boardstart :: Stringstart = "         " -- check if there is an X or an O at the given positionisPossible :: Int -> String -> BoolisPossible n game = (game !! n) `notElem` "XO" -- try to place an X or an O at a given position.-- "Right" + modified board means success, "Left" + unmodified board-- means failureplace :: Int -> Char -> String -> Either String Stringplace i c game =    if isPossible i game    then Right \$ take i game ++ [c] ++ drop (i + 1) game    else Left game -- COMPUTER AI-- get the number of movements, starting from a given non-empty board-- and a position for the next movement, until the specified player-- wins or no movement is possible-- the positions are chosen sequentially, so there's not much-- intelligence here anywaydevelopGame :: Bool -> Int -> Int -> Char -> String -> (Int, Char, String)developGame iterateMore moves i player game    | i > 8 =         -- if i arrives to the last position, iterate again from 0        -- but do it only once        if iterateMore        then developGame False moves 0 player game        -- draw game (after one iteration, still no winning moves)        else (moves, player, game)        -- draw game (game board full) or a win for the player    | moves == 9 || tictactoeFor player game = (moves, player, game)        -- make a move, if possible, and continue playing    | otherwise = case place i otherPlayer game of        -- position i is not empty. try with the next position        Left _ -> developGame iterateMore moves (i + 1)                    otherPlayer game        -- position i was empty, so it was a valid move.        -- change the player and make a new move, starting at pos 0        Right newGame -> developGame iterateMore (moves + 1) 0                    otherPlayer newGame        where            otherPlayer = changePlayer player -- COMPUTER AI-- starting from a given non-empty board, try to guess which position-- could lead the player to the fastest victory.bestMoveFor :: Char -> String -> IntbestMoveFor player game = bestMove    where        -- drive the game to its end for each starting position        continuations = [ (x, developGame True 0 x player game) |            x <- [0..8] ]        -- compare the number of moves of the game and take the        -- shortest one        move (_, (m, _, _)) = m        (bestMove, _) = minimumBy (comparing move) continuations -- canBlock checks if the opponent has two pieces in a row and the-- other cell in the row is empty, and places the player's piece there,-- blocking the opponentcanBlock :: Char -> String -> Maybe IntcanBlock p [a,b,c,d,e,f,g,h,i] =    listToMaybe \$ mapMaybe blockable [[a,b,c],[d,e,f],[g,h,i],[a,d,g],                                      [b,e,h],[c,f,i],[a,e,i],[c,e,g]]    where        blockable xs = do                    guard \$ length (filter (== otherPlayer) xs) == 2          x <- find (`elem` "123456789") xs          return \$ digitToInt x        otherPlayer = changePlayer p -- format a game board for on-screen printingshowGame :: String -> StringshowGame [a,b,c,d,e,f,g,h,i] =    topBottom ++    "|    | 1 | 2 | 3 |\n" ++    topBottom ++    row "0" [[a],[b],[c]] ++    row "3" [[d],[e],[f]] ++    row "6" [[g],[h],[i]]    where        topBottom = "+----+---+---+---+\n"        row n x = "| " ++ n ++ "+ | " ++            intercalate " | " x ++ " |\n" ++ topBottom -- ask the user to press a numeric key and convert it to an intenterNumber :: IO IntenterNumber = do    c <- getChar    if c `elem` "123456789"    then do        putStrLn ""        return \$ digitToInt c    else do        putStrLn "\nPlease enter a digit!"        enterNumber -- a human player's turn: get the number of pieces put on the board,-- the next piece to be put (X or O) and a game board, and return-- a new game state, checking if the piece can be placed on the board.-- if it can't, make the user try again.turn :: (Int, Char, String) -> IO (Int, Char, String)turn (count, player, game) = do    putStr \$ "Please tell me where you want to put an " ++        [player] ++ ": "    pos <- enterNumber    case place (pos - 1) player game of        Left oldGame -> do            putStrLn "That place is already taken!\n"            turn (count, player, oldGame)        Right newGame ->            return (count + 1, changePlayer player, newGame) -- alternate between X and O playerschangePlayer :: Char -> CharchangePlayer 'O' = 'X'changePlayer 'X' = 'O' -- COMPUTER AI-- make an automatic turn, placing an X or an O game board.-- the first movement is always random.-- first, the computer looks for two pieces of his opponent in a row-- and tries to block.-- otherwise, it tries to guess the best position for the next movement.-- as a last resort, it places a piece randomly.autoTurn :: Bool -> (Int, Char, String) -> IO (Int, Char, String)autoTurn forceRandom (count, player, game) = do    -- try a random position 'cause everything else failed    -- count == 0 overrides the value of forceRandom    i <- if count == 0 || forceRandom            then randomRIO (0,8)            else return \$                case canBlock player game of                    -- opponent can't be blocked. try to guess                    -- the best movement                    Nothing -> bestMoveFor player game                    -- opponent can be blocked, so just do it!                    Just blockPos -> blockPos    -- if trying to place a piece at a calculated position doesn't work,    -- just try again with a random value    case place i player game of        Left oldGame -> autoTurn True (count, player, oldGame)        Right newGame -> do            putStrLn \$ "It's player " ++ [player] ++ "'s turn."            return (count + 1, changePlayer player, newGame) -- play a game until someone wins or the board becomes full.-- depending on the value of the variable "auto", ask the user(s) to-- put some pieces on the board or do it automaticallyplay :: Int -> (Int, Char, String) -> IO ()play auto cpg@(_, player, game) = do    newcpg@(newCount, newPlayer, newGame) <- case auto of        -- if both players are human, always ask them        0 -> turn cpg        -- if both players are computer, always play auto        1 -> autoTurn False cpg        -- X is computer, O is human        2 -> if player == 'X' then autoTurn False cpg else turn cpg        -- X is human, O is computer        3 -> if player == 'O' then autoTurn False cpg else turn cpg    putStrLn \$ "\n" ++ showGame newGame    if tictactoe newGame    then putStrLn \$ "Player " ++ [changePlayer newPlayer] ++ " wins!\n"    else        if newCount == 9        then putStrLn "Draw!\n"        else play auto newcpg -- main program: greet the user, ask for a game type, ask for the-- player that'll start the game, and play the game beginning with an-- empty boardmain :: IO ()main = do    a <- getArgs    if null a    then usage    else do        let option = head a        if option `elem` ["0","1","2","3"]        then do            putStrLn \$ "\n" ++ showGame start            let m = read option :: Int            play m (0, 'X', start)        else usage usage :: IO ()usage = do    putStrLn "TIC-TAC-TOE GAME\n================\n"    putStrLn "How do you want to play?"    putStrLn "Run the program with one of the following options."    putStrLn "0 : both players are human"    putStrLn "1 : both players are computer"    putStrLn "2 : player X is computer and player O is human"    putStrLn "3 : player X is human and player O is computer"    putStrLn "Player X always begins." `
Output:

Player X is computer, O is human.

```+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ |   |   |   |
+----+---+---+---+
| 3+ |   |   |   |
+----+---+---+---+
| 6+ |   |   |   |
+----+---+---+---+

It's player X's turn.

+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ |   |   |   |
+----+---+---+---+
| 3+ |   | X |   |
+----+---+---+---+
| 6+ |   |   |   |
+----+---+---+---+

Please tell me where you want to put an O: 1

+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ | O |   |   |
+----+---+---+---+
| 3+ |   | X |   |
+----+---+---+---+
| 6+ |   |   |   |
+----+---+---+---+

It's player X's turn.

+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ | O |   | X |
+----+---+---+---+
| 3+ |   | X |   |
+----+---+---+---+
| 6+ |   |   |   |
+----+---+---+---+

Please tell me where you want to put an O: 7

+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ | O |   | X |
+----+---+---+---+
| 3+ |   | X |   |
+----+---+---+---+
| 6+ | O |   |   |
+----+---+---+---+

It's player X's turn.

+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ | O |   | X |
+----+---+---+---+
| 3+ | X | X |   |
+----+---+---+---+
| 6+ | O |   |   |
+----+---+---+---+

Please tell me where you want to put an O: 6

+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ | O |   | X |
+----+---+---+---+
| 3+ | X | X | O |
+----+---+---+---+
| 6+ | O |   |   |
+----+---+---+---+

It's player X's turn.

+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ | O |   | X |
+----+---+---+---+
| 3+ | X | X | O |
+----+---+---+---+
| 6+ | O | X |   |
+----+---+---+---+

Please tell me where you want to put an O: 2

+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ | O | O | X |
+----+---+---+---+
| 3+ | X | X | O |
+----+---+---+---+
| 6+ | O | X |   |
+----+---+---+---+

It's player X's turn.

+----+---+---+---+
|    | 1 | 2 | 3 |
+----+---+---+---+
| 0+ | O | O | X |
+----+---+---+---+
| 3+ | X | X | O |
+----+---+---+---+
| 6+ | O | X | X |
+----+---+---+---+

Draw!
```

## Icon and Unicon

The following works in both Icon and Unicon. The computer plays randomly against a human player, with legal moves enforced and wins/draws notified.

` # Play TicTacToe \$define E " " # empty square\$define X "X" # X piece\$define O "O" # O piece # -- define a board record Board(a, b, c, d, e, f, g, h, i) procedure display_board (board, player)  write ("\n===============")  write (board.a || " | " || board.b || " | " || board.c)  write ("---------")  write (board.d || " | " || board.e || " | " || board.f)  write ("---------")  write (board.g || " | " || board.h || " | " || board.i)end # return a set of valid moves (empty positions) in given boardprocedure empty_fields (board)  fields := set()  every i := !fieldnames(board) do     if (board[i] == E) then insert (fields, i)  return fieldsend procedure game_start ()  return Board (E, E, E, E, E, E, E, E, E)end procedure game_is_drawn (board)  return *empty_fields(board) = 0end procedure game_won_by (board, player)  return (board.a == board.b == board.c == player) |         (board.d == board.e == board.f == player) |         (board.g == board.h == board.i == player) |         (board.a == board.d == board.g == player) |          (board.b == board.e == board.h == player) |         (board.c == board.f == board.i == player) |         (board.a == board.e == board.i == player) |         (board.g == board.e == board.c == player)end procedure game_over (board)  return game_is_drawn (board) | game_won_by (board, O) | game_won_by (board, X)end # -- players make their move on the board#    assume there is at least one empty square procedure human_move (board, player)  choice := "z"  options := empty_fields (board)  # keep prompting until player selects a valid square  until member (options, choice) do {    writes ("Choose one of: ")    every writes (!options || " ")    writes ("\n> ")     choice := read ()  }  board[choice] := playerend # pick and make a move at random from empty positionsprocedure random_move (board, player)  board[?empty_fields(board)] := playerend # -- manage the game playprocedure play_game ()  # hold procedures for players' move in variables  player_O := random_move  player_X := human_move   # randomly determine if human or computer moves first  if (?2 = 0)     then {      write ("Human plays first as O")      player_O := human_move      player_X := random_move    }    else write ("Computer plays first, human is X")   # set up the game to start  board := game_start ()  player := O  display_board (board, player)  # loop until the game is over, getting each player to move in turn  until game_over (board) do {     write (player || " to play next")    # based on player, prompt for the next move    if (player == O)      then (player_O (board, player))      else (player_X (board, player))    # change player to move    player := if (player == O) then X else O    display_board (board, player)  }  # finish by writing out result  if game_won_by (board, O)     then write ("O won")     else if game_won_by (board, X)       then write ("X won")      else write ("draw") # neither player won, so must be a drawend # -- get things startedprocedure main ()  play_game ()end `

## J

To subsequent j poster: replacing this entry is fine by me.

` Note 'ttt adjudicates or plays'    use:  markers ttt characters    characters represent the cell names.    markers is a length 3 character vector of the   characters to use for first and second player   followed by the opponent's mark.   'XOX' means X plays 1st, O is the other mark,   and the first strategy plays 1st.   'XOO' means X plays 1st, O is the other mark,   and the second strategy moves first.    The game  is set  up for  the computer as the   first strategy (random), and human as second.    A standard use:      'XOX'ttt'abcdefghijkl'    Example game reformatted w/ emacs artist-mode   to fit your display:       '#-#'ttt'wersdfxcv'   w│e│r                     w│e│r        ....    -│e│r           .    -│e│#   ─┼─┼─                 .   ─┼─┼─       ..       ─┼─┼─         ..     ─┼─┼─   s│d│f                 .   s│#│f      ..        s│#│f        ..      -│#│f   ─┼─┼─                ..   ─┼─┼─      .         ─┼─┼─      ...       ─┼─┼─   x│c│v               ..    -│c│v      .         -│c│#     ..         -│c│#   d                  ..     v         ..         r         .          VICTORY   w│e│r             ..      w│e│r     ..         -│e│#     .   ─┼─┼─           ...       ─┼─┼─     ..         ─┼─┼─    .   s│#│f         ...         s│#│f     ..         s│#│f    .   ─┼─┼─        ..           ─┼─┼─   ...          ─┼─┼─  ...   x│c│v                     -│c│#                -│c│#   -->cell for -?            -->cell for -?       -->cell for -?   x                         w                    s) while=: conjunction def 'u ^: v ^:_' NB. j assumes while is a verb and needs to know while is a conjunction. ttt=: outcome@:((display@:move) while undecided)@:display@:prepare blindfolded_variant=: outcome@:display@:(move while undecided)@:display@:prepare outcome=: {&(>;:'kitty VICTORY')@:won   NB. (outcome does not pass along the state)move=: post locateundecided=: won nor fullprepare=: , board@:]                    NB. form the state vector Note 'locate'  is a monadic verb.  y is the state vector.  returns the character of the chosen cell.  Generally:  locate=: second_strategy`first_strategy@.(first = mark)  Simplified:  locate=: human_locate NB. human versus human)locate=: human_locate`computer_locate@.(first = mark) display=: show [: (1 1,:5 5)&(];.0)@:": [: <"0 fold computer_locate=: [: show@{. board -. marks NB. strategy: first availablecomputer_locate=: [: show@({~ ?@:#) board -. marks NB. strategy: random human_locate=: monad define  state=. y  m=. mark state  b=. board state  cells=. b -. marks state  show '-->cell for ' , m , '?'  whilst. cell -.@:e. cells do. cell =. {. (1!:1]1) , m end.) post=: 2&A.@:(3&{.)@:[ prepare mark@:[`((i.~ board)~)`(board@:[)} mark=: {.                    NB. mark of the current player from statemarks=: 2&{.                 NB. extract both markers from stateboard=: _9&{.                NB. extract board from statefirst=: 2&{                  NB. extract first player from state show=: [ smoutput full=: 2 = #@:~.won=: test@:foldfold=: 3 3 \$ boardtest=: [: any [: all [: infix_pairs_agree |:@:lines lines=: , diagonal , diagonal@:|. , |:diagonal=: (<0 1)&|:all=: *./any=: +./nor=: 8 b.infix_pairs_agree=: 2&(=/\) `

## Java

This version works in the terminal itself, and uses the numpad for data entry. The computer is unbeatable, but some lines can be removed to avoid that. There's also an override that thrown in, just for fun.

` import java.io.BufferedReader;import java.io.InputStreamReader;import java.util.Hashtable; public class TicTacToe{	public static void main(String[] args)	{		TicTacToe now=new TicTacToe();		now.startMatch();	} 	private int[][] marks;	private int[][] wins;	private int[] weights;	private char[][] grid;	private final int knotcount=3;	private final int crosscount=4;	private final int totalcount=5;	private final int playerid=0;	private final int compid=1;	private final int truceid=2;	private final int playingid=3;	private String movesPlayer;	private byte override;	private char[][] overridegrid={{'o','o','o'},{'o','o','o'},{'o','o','o'}};	private char[][] numpad={{'7','8','9'},{'4','5','6'},{'1','2','3'}};	private Hashtable<Integer,Integer> crossbank;	private Hashtable<Integer,Integer> knotbank; 	public void startMatch()	{		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));		System.out.print("Start?(y/n):");		char choice='y';		try		{			choice=br.readLine().charAt(0);		}		catch(Exception e)		{			System.out.println(e.getMessage());		}		if(choice=='n'||choice=='N')		{			return;		} 		System.out.println("Use a standard numpad as an entry grid, as so:\n ");		display(numpad);		System.out.println("Begin");		int playerscore=0;		int compscore=0;		do		{			int result=startGame();			if(result==playerid)				playerscore++;			else if(result==compid)				compscore++;			System.out.println("Score: Player-"+playerscore+" AI-"+compscore);			System.out.print("Another?(y/n):");			try			{				choice=br.readLine().charAt(0);			}			catch(Exception e)			{				System.out.println(e.getMessage());			} 		}while(choice!='n'||choice=='N'); 		System.out.println("Game over.");	}	private void put(int cell,int player)	{		int i=-1,j=-1;;		switch(cell)		{		case 1:i=2;j=0;break;		case 2:i=2;j=1;break;		case 3:i=2;j=2;break;		case 4:i=1;j=0;break;		case 5:i=1;j=1;break;		case 6:i=1;j=2;break;		case 7:i=0;j=0;break;		case 8:i=0;j=1;break;		case 9:i=0;j=2;break;		default:display(overridegrid);return;		}		char mark='x';		if(player==0)			mark='o';		grid[i][j]=mark;		display(grid);	}	private int startGame()	{		init();		display(grid);		int status=playingid;		while(status==playingid)		{			put(playerMove(),0);			if(override==1)			{				System.out.println("O wins.");				return playerid;			}			status=checkForWin();			if(status!=playingid)				break;			try{Thread.sleep(1000);}catch(Exception e){System.out.print(e.getMessage());}			put(compMove(),1);			status=checkForWin();		}		return status;	}	private void init()	{		movesPlayer="";		override=0;		marks=new int[8][6];		wins=new int[][]	//new int[8][3];		{					{7,8,9},				{4,5,6},				{1,2,3},				{7,4,1},				{8,5,2},				{9,6,3},				{7,5,3},				{9,5,1}		};		weights=new int[]{3,2,3,2,4,2,3,2,3};		grid=new char[][]{{' ',' ',' '},{' ',' ',' '},{' ',' ',' '}};		crossbank=new Hashtable<Integer,Integer>();		knotbank=new Hashtable<Integer,Integer>();	}	private void mark(int m,int player)	{		for(int i=0;i<wins.length;i++)			for(int j=0;j<wins[i].length;j++)				if(wins[i][j]==m)				{					marks[i][j]=1;					if(player==playerid)						marks[i][knotcount]++;					else						marks[i][crosscount]++;					marks[i][totalcount]++;				}	}	private void fixWeights()	{		for(int i=0;i<3;i++)			for(int j=0;j<3;j++)				if(marks[i][j]==1)					if(weights[wins[i][j]-1]!=Integer.MIN_VALUE)						weights[wins[i][j]-1]=Integer.MIN_VALUE; 		for(int i=0;i<8;i++)		{			if(marks[i][totalcount]!=2)				continue;			if(marks[i][crosscount]==2)			{				int p=i,q=-1;				if(marks[i][0]==0)					q=0;				else if(marks[i][1]==0)					q=1;				else if(marks[i][2]==0)					q=2; 				if(weights[wins[p][q]-1]!=Integer.MIN_VALUE)				{					weights[wins[p][q]-1]=6;				}			}			if(marks[i][knotcount]==2)			{				int p=i,q=-1;				if(marks[i][0]==0)					q=0;				else if(marks[i][1]==0)					q=1;				else if(marks[i][2]==0)					q=2; 				if(weights[wins[p][q]-1]!=Integer.MIN_VALUE)				{					weights[wins[p][q]-1]=5;				}			}		}	}	private int compMove()	{		int cell=move();		System.out.println("Computer plays: "+cell);		//weights[cell-1]=Integer.MIN_VALUE;		return cell;	}	private int move()	{		int max=Integer.MIN_VALUE;		int cell=0;		for(int i=0;i<weights.length;i++)			if(weights[i]>max)			{				max=weights[i];				cell=i+1;			} 		//This section ensures the computer never loses		//Remove it for a fair match		//Dirty kluge		if(movesPlayer.equals("76")||movesPlayer.equals("67"))			cell=9;		else if(movesPlayer.equals("92")||movesPlayer.equals("29"))			cell=3;		else if (movesPlayer.equals("18")||movesPlayer.equals("81"))			cell=7;		else if(movesPlayer.equals("73")||movesPlayer.equals("37"))			cell=4*((int)(Math.random()*2)+1);		else if(movesPlayer.equals("19")||movesPlayer.equals("91"))			cell=4+2*(int)(Math.pow(-1, (int)(Math.random()*2))); 		mark(cell,1);		fixWeights();		crossbank.put(cell, 0);		return cell;	}	private int playerMove()	{		System.out.print("What's your move?: ");		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));		int cell=0;		int okay=0;		while(okay==0)		{			try			{				cell=Integer.parseInt(br.readLine());			}			catch(Exception e)			{				System.out.println(e.getMessage());			}			if(cell==7494)			{				override=1;				return -1;			}			if((cell<1||cell>9)||weights[cell-1]==Integer.MIN_VALUE)				System.out.print("Invalid move. Try again:");			else				okay=1;		}		playerMoved(cell);		System.out.println();		return cell;	}	private void playerMoved(int cell)	{		movesPlayer+=cell;		mark(cell,0);		fixWeights();		knotbank.put(cell, 0);	}	private int checkForWin()	{		int crossflag=0,knotflag=0;		for(int i=0;i<wins.length;i++)		{			if(crossbank.containsKey(wins[i][0]))				if(crossbank.containsKey(wins[i][1]))					if(crossbank.containsKey(wins[i][2]))					{						crossflag=1;						break;					}			if(knotbank.containsKey(wins[i][0]))				if(knotbank.containsKey(wins[i][1]))					if(knotbank.containsKey(wins[i][2]))					{						knotflag=1;						break;					}		}		if(knotflag==1)		{			display(grid);			System.out.println("O wins.");			return playerid;		}		else if(crossflag==1)		{			display(grid);			System.out.println("X wins.");			return compid;		} 		for(int i=0;i<weights.length;i++)			if(weights[i]!=Integer.MIN_VALUE)				return playingid;		System.out.println("Truce"); 		return truceid;	}	private void display(char[][] grid)	{		for(int i=0;i<3;i++)		{			System.out.println("\n-------");			System.out.print("|");			for(int j=0;j<3;j++)				System.out.print(grid[i][j]+"|");		}		System.out.println("\n-------");	}} `
```Start?(y/n):y
Use a standard numpad as an entry grid, as so:
-------
|7|8|9|
-------
|4|5|6|
-------
|1|2|3|
-------
Begin

-------
| | | |
-------
| | | |
-------
| | | |
-------

-------
| | | |
-------
|o| | |
-------
| | | |
-------

(...)

Computer plays: 7
-------
|x| |o|
-------
|o|x|o|
-------
|x|o|x|
-------
X wins.

Score: Player-0 AI-1
Another?(y/n):n
Game over.
```

This version uses javax.swing.

`import javax.swing.*;import java.awt.*;import java.awt.event.*;import java.util.logging.Logger;/** * TicTacToe Application* @author Steve Robinson* @version 1.0*/class TicTacToeFrame extends JFrame{ JButton [][] buttons= new JButton[3][3]; JTextField statusBar; GamePanel panel; Integer turn; GameListener listener=new GameListener(); Integer count; public TicTacToeFrame() {setLayout(new BorderLayout());  panel=new GamePanel();  add(panel,BorderLayout.CENTER);  statusBar=new JTextField("Player1's Turn");  statusBar.setEditable(false);  add(statusBar,BorderLayout.SOUTH);  setTitle("Tic Tac Toe!");  setVisible(true);  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  setBounds(400,400,300,300); } class GamePanel extends JPanel {  public GamePanel()  {   setLayout(new GridLayout(3,3));   turn =1;   count=0;   for(int i=0;i<3;i++)    for(int j=0;j<3;j++)   {     buttons[i][j]=new JButton();     buttons[i][j].putClientProperty("INDEX", new Integer[]{i,j});     buttons[i][j].putClientProperty("OWNER", null);     buttons[i][j].addActionListener(listener);     add(buttons[i][j]);    }  } } class GameListener implements ActionListener {  public void actionPerformed(ActionEvent e)  {   count++;   JButton b=(JButton)e.getSource();   Integer[]index=(Integer[]) b.getClientProperty("INDEX");   //System.out.println(turn); //turn                  //   //System.out.println("["+index[0]+"]"+"["+index[1]+"]");         //   b.putClientProperty("OWNER", turn);   Icon ico=new ImageIcon(turn.toString()+".gif");   b.setIcon(ico);   b.setEnabled(false);   boolean result=checkVictoryCondition(index);   if(result)   {    JOptionPane.showMessageDialog(null, "Player "+turn.toString()+" Wins");    initComponents();   }   else   {    if(turn==1)    {     turn=2;     statusBar.setText("Player2's Turn");    }    else    {     turn=1;     statusBar.setText("Player1's Turn");    }   }   if(count==9)   {    JOptionPane.showMessageDialog(null, "Match is a draw!");    initComponents();   }  }  Integer getOwner(JButton b)  {   return (Integer)b.getClientProperty("OWNER");  }  //PrintButtonMap for Diagnostics  void printbuttonMap(Integer [][]bMap)  {   for(int i=0;i    for(int j=0;j     System.out.print(bMap[i][j]+" ");    System.out.println("");   }  }  boolean checkVictoryCondition(Integer [] index)  {   /*Integer[][]buttonMap=new Integer[][] {      { getOwner(buttons[0][0]),getOwner(buttons[0][1]),getOwner(buttons[0][2])},      { getOwner(buttons[1][0]),getOwner(buttons[1][1]),getOwner(buttons[1][2])},      { getOwner(buttons[2][0]),getOwner(buttons[2][1]),getOwner(buttons[2][2])}   };   printbuttonMap(buttonMap); */   Integer a=index[0];                Integer b=index[1];   int i;   //check row   for(i=0;i<3;i++)  {    if(getOwner(buttons[a][i])!=getOwner(buttons[a][b]))     break;   }   if(i==3)    return true;   //check column   for(i=0;i<3;i++)  {    if(getOwner(buttons[i][b])!=getOwner(buttons[a][b]))     break;   }   if(i==3)    return true;   //check diagonal   if((a==2&&b==2)||(a==0&&b==0)||(a==1&&b==1)||(a==0&&b==2)||(a==2&&b==0))   {    //left diagonal    for(i=0;i     if(getOwner(buttons[i][i])!=getOwner(buttons[a][b]))      break;    if(i==3)     return true;    //right diagonal    if((getOwner(buttons[0][2])==getOwner(buttons[a][b]))&&(getOwner(buttons[1][1])==getOwner(buttons[a][b]))&&(getOwner(buttons[2][0])==getOwner(buttons[a][b])))     return true;    }   return false;  } } void initComponents() {  for(int i=0;i<3;i++)     for(int j=0;j<3;j++)  {    buttons[i][j].putClientProperty("INDEX", new Integer[]{i,j});    buttons[i][j].putClientProperty("OWNER",null);    buttons[i][j].setIcon(null);    buttons[i][j].setEnabled(true);    turn=1;    count=0;    statusBar.setText("Player1's Turn");   } }}class TicTacToe { public static void main(String[] args) {  EventQueue.invokeLater(new Runnable(){   public void run()   {    TicTacToeFrame frame=new TicTacToeFrame();   }  }); }} `

Graphical Java Example

` import javax.swing.*;import java.awt.event.*;import java.awt.*;  //Make sure the name of the class is the same as the .java file name.//If you change the class name you should change the class object name in runGUI methodpublic class ticTacToeCallum implements ActionListener {   static JFrame frame;            static JPanel contentPane;      static JLabel lblEnterFirstPlayerName, lblEnterSecondPlayerName, lblFirstPlayerScore, lblSecondPlayerScore;      static JButton btnButton1, btnButton2, btnButton3, btnButton4, btnButton5, btnButton6, btnButton7, btnButton8, btnButton9, btnClearBoard, btnClearAll, btnCloseGame;       static JTextField txtEnterFirstPlayerName, txtEnterSecondPlayerName;    static Icon imgicon = new ImageIcon("saveIcon.JPG");   Font buttonFont = new Font("Arial", Font.PLAIN, 20);    //to adjust the frame size change the values in pixels  static int width = 600;  static int length = 400;  static int firstPlayerScore = 0;  static int secondPlayerScore = 0;  static int playerTurn = 1;  static int roundComplete = 0;  static int button1 = 1, button2 = 1, button3 = 1, button4 = 1, button5 = 1, button6 = 1, button7 = 1, button8 = 1, button9 = 1; // 1 is true, 0 is false    public ticTacToeCallum(){     frame = new JFrame("Tic Tac Toe ^_^");    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);     contentPane = new JPanel();    contentPane.setLayout(new GridLayout(6, 3, 10, 10));    contentPane.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));     btnButton1 = new JButton("");    btnButton1.setFont(buttonFont);    btnButton1.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnButton1.setIcon(imgicon);    btnButton1.setActionCommand("CLICK1");        btnButton1.addActionListener(this);      contentPane.add(btnButton1);     btnButton2 = new JButton("");    btnButton2.setFont(buttonFont);    btnButton2.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnButton2.setIcon(imgicon);    btnButton2.setActionCommand("CLICK2");        btnButton2.addActionListener(this);          contentPane.add(btnButton2);     btnButton3 = new JButton("");     btnButton3.setFont(buttonFont);    btnButton3.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnButton3.setIcon(imgicon);    btnButton3.setActionCommand("CLICK3");        btnButton3.addActionListener(this);          contentPane.add(btnButton3);     btnButton4 = new JButton("");    btnButton4.setFont(buttonFont);    btnButton4.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnButton4.setIcon(imgicon);    btnButton4.setActionCommand("CLICK4");        btnButton4.addActionListener(this);          contentPane.add(btnButton4);     btnButton5 = new JButton("");     btnButton5.setFont(buttonFont);    btnButton5.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnButton5.setIcon(imgicon);    btnButton5.setActionCommand("CLICK5");        btnButton5.addActionListener(this);          contentPane.add(btnButton5);     btnButton6 = new JButton("");     btnButton6.setFont(buttonFont);    btnButton6.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnButton6.setIcon(imgicon);    btnButton6.setActionCommand("CLICK6");        btnButton6.addActionListener(this);          contentPane.add(btnButton6);     btnButton7 = new JButton("");     btnButton7.setFont(buttonFont);    btnButton7.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnButton7.setIcon(imgicon);    btnButton7.setActionCommand("CLICK7");        btnButton7.addActionListener(this);          contentPane.add(btnButton7);     btnButton8 = new JButton("");     btnButton8.setFont(buttonFont);    btnButton8.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnButton8.setIcon(imgicon);    btnButton8.setActionCommand("CLICK8");        btnButton8.addActionListener(this);          contentPane.add(btnButton8);     btnButton9 = new JButton("");    btnButton9.setFont(buttonFont);    btnButton9.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnButton9.setIcon(imgicon);    btnButton9.setActionCommand("CLICK9");        btnButton9.addActionListener(this);          contentPane.add(btnButton9);     lblEnterFirstPlayerName = new JLabel("Enter First Player's Name");    contentPane.add(lblEnterFirstPlayerName);     txtEnterFirstPlayerName = new JTextField("");    contentPane.add(txtEnterFirstPlayerName);     lblFirstPlayerScore = new JLabel("Score: " + firstPlayerScore);    contentPane.add(lblFirstPlayerScore);     lblEnterSecondPlayerName = new JLabel("Enter Second Player's Name");    contentPane.add(lblEnterSecondPlayerName);     txtEnterSecondPlayerName = new JTextField("");    contentPane.add(txtEnterSecondPlayerName);     lblSecondPlayerScore = new JLabel("Score: " + secondPlayerScore);    contentPane.add(lblSecondPlayerScore);     btnClearBoard = new JButton("Clear Board");      btnClearBoard.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnClearBoard.setIcon(imgicon);    btnClearBoard.setActionCommand("CLICKClearBoard");        btnClearBoard.addActionListener(this);          contentPane.add(btnClearBoard);     btnClearAll = new JButton("Clear All");      btnClearAll.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnClearAll.setIcon(imgicon);    btnClearAll.setActionCommand("CLICKClearAll");        btnClearAll.addActionListener(this);          contentPane.add(btnClearAll);     btnCloseGame = new JButton("Close Game");     btnCloseGame.setAlignmentX(JButton.CENTER_ALIGNMENT);    btnCloseGame.setIcon(imgicon);    btnCloseGame.setActionCommand("CLICKCloseGame");        btnCloseGame.addActionListener(this);          contentPane.add(btnCloseGame);     frame.setContentPane(contentPane);    frame.pack();    frame.setSize(width,length);    frame.setVisible(true);   }   public void actionPerformed(ActionEvent event) {    String eventName = event.getActionCommand();     if (eventName.equals("CLICK1")) {    	 if (button1 == 1){    		 if (playerTurn == 1){    			 btnButton1.setForeground(Color.RED);    			 btnButton1.setText("X");   	  			 playerTurn = 2;    			 button1 = 0;    		 } else if (playerTurn == 2) {    			 btnButton1.setForeground(Color.GREEN);    			 btnButton1.setText("O");    			 playerTurn = 1;    			 button1 = 0;    		 }    	 }      } else if (eventName.equals ("CLICK2")) {    	  if (button2 == 1){	    	  	if (playerTurn == 1){    	  		btnButton2.setForeground(Color.RED);    	  		btnButton2.setText("X");  	  			playerTurn = 2;    	  		button2 = 0;    	  	} else if (playerTurn == 2) {    	  		btnButton2.setForeground(Color.GREEN);    	  		btnButton2.setText("O");    	  		playerTurn = 1;    	  		button2 = 0;    	  	}    	  }	      }	else if (eventName.equals ("CLICK3")) {    	  if (button3 == 1){	      	  	if (playerTurn == 1){      	  		btnButton3.setForeground(Color.RED);      	  		btnButton3.setText("X");  	  			playerTurn = 2;      	  		button3 = 0;      	  	} else if (playerTurn == 2) {      	  		btnButton3.setForeground(Color.GREEN);      	  		btnButton3.setText("O");      	  		playerTurn = 1;      	  		button3 = 0;      	  	}      	  }      }	else if (eventName.equals ("CLICK4")) {    	  if (button4 == 1){	      	  	if (playerTurn == 1){      	  		btnButton4.setForeground(Color.RED);      	  		btnButton4.setText("X");  	  			playerTurn = 2;      	  		button4 = 0;      	  	} else if (playerTurn == 2) {      	  		btnButton4.setForeground(Color.GREEN);      	  		btnButton4.setText("O");      	  		playerTurn = 1;      	  		button4 = 0;      	  	}      	  }      }	else if (eventName.equals ("CLICK5")) {    	  if (button5 == 1){	      	  	if (playerTurn == 1){      	  		btnButton5.setForeground(Color.RED);  	  			btnButton5.setText("X");  	  			playerTurn = 2;  	  			button5 = 0;      	  	} else if (playerTurn == 2) {      	  		btnButton5.setForeground(Color.GREEN);  	  			btnButton5.setText("O");  	  			playerTurn = 1;  	  			button5 = 0;      	  	}      	  }      } else if (eventName.equals ("CLICK6")) {    	  if (button6 == 1){	      	  	if (playerTurn == 1){      	  		btnButton6.setForeground(Color.RED);  	  			btnButton6.setText("X");  	  			playerTurn = 2;  	  			button6 = 0;      	  	} else if (playerTurn == 2) {      	  		btnButton6.setForeground(Color.GREEN);  	  			btnButton6.setText("O");  	  			playerTurn = 1;  	  			button6 = 0;      	  	}      	  }      } else if (eventName.equals ("CLICK7")) {    	  if (button7 == 1){	      	  	if (playerTurn == 1){      	  		btnButton7.setForeground(Color.RED);  	  			btnButton7.setText("X");  	  			playerTurn = 2;  	  			button7 = 0;      	  	} else if (playerTurn == 2) {      	  		btnButton7.setForeground(Color.GREEN);  	  			btnButton7.setText("O");  	  			playerTurn = 1;  	  			button7 = 0;      	  	}      	  }      } else if (eventName.equals ("CLICK8")) {    	  if (button8 == 1){	      	  	if (playerTurn == 1){      	  		btnButton8.setForeground(Color.RED);  	  			btnButton8.setText("X");  	  			playerTurn = 2;  	  			button8 = 0;      	  	} else if (playerTurn == 2) {      	  		btnButton8.setForeground(Color.GREEN);  	  			btnButton8.setText("O");  	  			playerTurn = 1;  	  			button8 = 0;      	  	}      	  }      } else if (eventName.equals ("CLICK9")) {    	  if (button9 == 1){	      	  	if (playerTurn == 1){      	  		btnButton9.setForeground(Color.RED);  	  			btnButton9.setText("X");  	  			playerTurn = 2;  	  			button9 = 0;      	  	} else if (playerTurn == 2) {      	  		btnButton9.setForeground(Color.GREEN);  	  			btnButton9.setText("O");  	  			playerTurn = 1;  	  			button9 = 0;      	  	}      	  }      } else if (eventName.equals ("CLICKClearBoard")) {     	  btnButton1.setText("");          btnButton2.setText("");          btnButton3.setText("");          btnButton4.setText("");          btnButton5.setText("");          btnButton6.setText("");          btnButton7.setText("");          btnButton8.setText("");          btnButton9.setText("");           button1 = 1;          button2 = 1;          button3 = 1;          button4 = 1;          button5 = 1;          button6 = 1;          button7 = 1;          button8 = 1;          button9 = 1;           playerTurn = 1;           roundComplete = 0;       } else if (eventName.equals ("CLICKClearAll")) {     	  btnButton1.setText("");          btnButton2.setText("");          btnButton3.setText("");          btnButton4.setText("");          btnButton5.setText("");          btnButton6.setText("");          btnButton7.setText("");          btnButton8.setText("");          btnButton9.setText("");           firstPlayerScore = 0;          lblFirstPlayerScore.setText("Score: " + firstPlayerScore);          secondPlayerScore = 0;          lblSecondPlayerScore.setText("Score: " + secondPlayerScore);           txtEnterFirstPlayerName.setText("");          txtEnterSecondPlayerName.setText("");           button1 = 1;          button2 = 1;          button3 = 1;          button4 = 1;          button5 = 1;          button6 = 1;          button7 = 1;          button8 = 1;          button9 = 1;           playerTurn = 1;           roundComplete = 0;       } else if (eventName.equals ("CLICKCloseGame")) {    	  System.exit(0);      }       score();    }    public static void score(){	  if (roundComplete == 0){	  if (btnButton1.getText().equals(btnButton2.getText())  && btnButton1.getText().equals(btnButton3.getText())){	    	if (btnButton1.getText().equals("X")){	    		firstPlayerScore += 1;	    		lblFirstPlayerScore.setText("Score: " + firstPlayerScore);	    		roundComplete = 1;	    	} else if (btnButton1.getText().equals("O")){	    		secondPlayerScore += 1;	    		lblSecondPlayerScore.setText("Score: " + secondPlayerScore);	    		roundComplete = 1;	    	}	    }	    if (btnButton1.getText().equals(btnButton4.getText())  && btnButton1.getText().equals(btnButton7.getText())){	    	if (btnButton1.getText().equals("X")){	    		firstPlayerScore += 1;	    		lblFirstPlayerScore.setText("Score: " + firstPlayerScore);	    		roundComplete = 1;	    	} else if (btnButton1.getText().equals("O")){	    		secondPlayerScore += 1;	    		lblSecondPlayerScore.setText("Score: " + secondPlayerScore);	    		roundComplete = 1;	    	}	    }	    if (btnButton1.getText().equals(btnButton5.getText())  && btnButton1.getText().equals(btnButton9.getText())){	    	if (btnButton1.getText().equals("X")){	    		firstPlayerScore += 1;	    		lblFirstPlayerScore.setText("Score: " + firstPlayerScore);	    		roundComplete = 1;	    	} else if (btnButton1.getText().equals("O")){	    		secondPlayerScore += 1;	    		lblSecondPlayerScore.setText("Score: " + secondPlayerScore);	    		roundComplete = 1;	    	}	    }	    if (btnButton7.getText().equals(btnButton8.getText())  && btnButton7.getText().equals(btnButton9.getText())){	    	if (btnButton7.getText().equals("X")){	    		firstPlayerScore += 1;	    		lblFirstPlayerScore.setText("Score: " + firstPlayerScore);	    		roundComplete = 1;	    	} else if (btnButton7.getText().equals("O")){	    		secondPlayerScore += 1;	    		lblSecondPlayerScore.setText("Score: " + secondPlayerScore);	    		roundComplete = 1;	    	}	    }	    if (btnButton7.getText().equals(btnButton5.getText())  && btnButton7.getText().equals(btnButton3.getText())){	    	if (btnButton7.getText().equals("X")){	    		firstPlayerScore += 1;	    		lblFirstPlayerScore.setText("Score: " + firstPlayerScore);	    		roundComplete = 1;	    	} else if (btnButton7.getText().equals("O")){	    		secondPlayerScore += 1;	    		lblSecondPlayerScore.setText("Score: " + secondPlayerScore);	    		roundComplete = 1;	    	}	    }	    if (btnButton3.getText().equals(btnButton6.getText())  && btnButton3.getText().equals(btnButton9.getText())){	    	if (btnButton3.getText().equals("X")){	    		firstPlayerScore += 1;	    		lblFirstPlayerScore.setText("Score: " + firstPlayerScore);	    		roundComplete = 1;	    	} else if (btnButton3.getText().equals("O")){	    		secondPlayerScore += 1;	    		lblSecondPlayerScore.setText("Score: " + secondPlayerScore);	    		roundComplete = 1;	    	}	    }	    if (btnButton4.getText().equals(btnButton5.getText())  && btnButton4.getText().equals(btnButton6.getText())){	    	if (btnButton4.getText().equals("X")){	    		firstPlayerScore += 1;	    		lblFirstPlayerScore.setText("Score: " + firstPlayerScore);	    		roundComplete = 1;	    	} else if (btnButton4.getText().equals("O")){	    		secondPlayerScore += 1;	    		lblSecondPlayerScore.setText("Score: " + secondPlayerScore);	    		roundComplete = 1;	    	}	    }	    if (btnButton2.getText().equals(btnButton5.getText())  && btnButton2.getText().equals(btnButton8.getText())){	    	if (btnButton2.getText().equals("X")){	    		firstPlayerScore += 1;	    		lblFirstPlayerScore.setText("Score: " + firstPlayerScore);	    		roundComplete = 1;	    	} else if (btnButton2.getText().equals("O")){	    		secondPlayerScore += 1;	    		lblSecondPlayerScore.setText("Score: " + secondPlayerScore);	    		roundComplete = 1;	    	}	    }	  }	    if (roundComplete == 1){	    	button1 = 0;	    	button2 = 0;	    	button3 = 0;	    	button4 = 0;	    	button5 = 0;	    	button6 = 0;	    	button7 = 0;	    	button8 = 0;	    	button9 = 0;	    }  }   /**   * Create and show the GUI.   */  private static void runGUI() {    ticTacToeCallum        greeting     = new ticTacToeCallum();  }     //Do not change this method  public static void main(String[] args) {    /* Methods that create and show a GUI should be run from an event-dispatching thread */    javax.swing.SwingUtilities.invokeLater(new Runnable() {      public void run() {        runGUI();      }    });  }} `

## Lasso

 This example is incomplete. Computer doesn't play - it merely manages the board. Please ensure that it meets all task requirements and remove this message.

This example uses an HTML form for the UI, buttons representing the game state, and Lasso's built inn session handler to keep track of who's turn it is, what the game matrix state is, and the winner history.

As image uploads has been disabled, a live version can be viewed at: http://jono.guthrie.net.nz/rosetta/Tic-tac-toe.lasso

`[session_start('user')session_addvar('user', 'matrix')session_addvar('user', 'winrecord')session_addvar('user', 'turn')var(matrix)->isNotA(::array) ? var(matrix = array('-','-','-','-','-','-','-','-','-'))var(winrecord)->isNotA(::array) ? var(winrecord = array)var(turn)->isNotA(::string) ? var(turn = 'x') if(web_request->params->asStaticArray >> 'reset') => {	\$matrix = array('-','-','-','-','-','-','-','-','-')	\$turn = 'x'} with i in web_request->params->asStaticArray do => {	if(#i->name->beginswith('p')) => {		local(num = #i->name->asCopy)		#num->removeLeading('p')		#num = integer(#num)		#num > 0 && \$matrix->get(#num) == '-' ? \$matrix->get(#num) = #i->value		\$turn == 'o' ? \$turn = 'x' | \$turn = 'o'	}} local(	istie 	= false,	winner	= 'noone',	clear	= false) // determine if we have a winnerif(\$matrix->find('-')->size < 9) => {	local(winners = array('123','456','789','147','258','369','159','357'))	loop(8) => {		local(xscore = 0,oscore = 0,use = #winners->get(loop_count))		with v in #use->values do => {			\$matrix->findposition('x') >> integer(#v) ? #xscore++			\$matrix->findposition('o') >> integer(#v) ? #oscore++		}		if(#xscore == 3) => {			#winner = 'x'			\$winrecord->insert('x')			#clear = true			loop_abort		}		if(#oscore == 3) => {			#winner = 'o'			\$winrecord->insert('o')			#clear = true			loop_abort		} 	} }// determine if tieif(not \$matrix->find('-')->size && #winner == 'noone') => {	#istie = true	#winner = 'tie'	\$winrecord->insert('tie')	#clear = true}]<form action="?" method="post">  <table>    <tr>      [loop(3) => {^]<td><button name="p[loop_count]" value="[\$turn]"[        \$matrix->get(loop_count) != '-' || #winner != 'noone' ? ' disabled="disabled"'      ]>[\$matrix->get(loop_count) != '-' ? \$matrix->get(loop_count) | ' ']</button></td>[^}]    </tr>    <tr>      [loop(-from=4,-to=6) => {^]<td><button name="p[loop_count]" value="[\$turn]"[        \$matrix->get(loop_count) != '-' || #winner != 'noone' ? ' disabled="disabled"'      ]>[\$matrix->get(loop_count) != '-' ? \$matrix->get(loop_count) | ' ']</button></td>[^}]    </tr>    <tr>      [loop(-from=7,-to=9) => {^]<td><button name="p[loop_count]" value="[\$turn]"[        \$matrix->get(loop_count) != '-' || #winner != 'noone' ? ' disabled="disabled"'      ]>[\$matrix->get(loop_count) != '-' ? \$matrix->get(loop_count) | ' ']</button></td>[^}]    </tr>  </table></form>[if(#istie && #winner == 'tie')]<p><b>It's a tie!</b></p>[else(#winner != 'noone')]<p>[#winner->uppercase&] won! Congratulations.</p>[else][itex]Insert formula here[/itex]<p>It is now [\$turn]'s turn!</p>[/if]<p><a href="?reset">Reset</a></p>[if(\$winrecord->size)]<p>Win record: [\$winrecord->join(', ')]</p>[/if][if(#clear == true) => {	\$matrix = array('-','-','-','-','-','-','-','-','-')	\$turn = 'x'}]`

## Mathematica

`DynamicModule[{board = ConstantArray[0, {3, 3}], text = "Playing...",   first, rows =    Join[#, Transpose@#, {Diagonal@#, [email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */@#}] &},  Column@{Graphics[{Thickness[.02],      Table[With[{i = i, j = j},        Button[{White, Rectangle[{i, j} - 1, {i, j}], Black,          Dynamic[Switch[board[[i, j]], 0, Black, 1,            Circle[{i, j} - .5, .3], -1,            Line[{{{i, j} - .2, {i, j} - .8}, {{i - .2,                j - .8}, {i - .8, j - .2}}}]]]},         Which[text != "Playing...", board = ConstantArray[0, {3, 3}];         text = "Playing...", board[[i, j]] == 0,          If[board == ConstantArray[0, {3, 3}],           first = {i,              j} /. {{2, 2} -> 1, {1 | 3, 1 | 3} -> 2, _ -> 3}];          board[[i, j]] = 1;         FinishDynamic[];         Which[MemberQ[rows[board], {1, 1, 1}], text = "You win.",           FreeQ[board, 0], text = "Draw.", True,           board[[Sequence @@               SortBy[Select[Tuples[[email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */, [email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */}],                  board[[Sequence @@ #]] ==                    0 &], -Total[                    Sort /@                     rows[ReplacePart[                    board, # -> -1]] /. {{-1, -1, -1} ->                     512, {-1, 1, 1} -> 64, {-1, -1, 0} ->                     8, {0, 1, 1} -> -1, {_, _, _} -> 0}] -                   Switch[#, {2, 2}, 1, {1 | 3, 1 | 3},                    If[first == 2, -1, 0], _,                    If[first == 2, 0, -1]] &][[1]]]] = -1;           Which[MemberQ[rows[board], {-1, -1, -1}],            text = "You lost.", FreeQ[board, 0],            text = "Draw."]]]]], {i, 1, 3}, {j, 1, 3}], Thickness[.01],      Line[{{{1, 0}, {1, 3}}, {{2, 0}, {2, 3}}, {{0, 1}, {3, 1}}, {{0,          2}, {3, 2}}}]}], [email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */}]`

## MATLAB

Allows for choice between any combination of human or computer players. Computer players are intelligent, but not perfect. It implements the "rules" used by the Newell and Simon's 1972 tic-tac-toe program (as explained by Wikipedia), but this implementation does not factor in the move before the move causing the fork (either for creation or prevention).

`function TicTacToe     % Set up the board (one for each player)    boards = false(3, 3, 2);    % Players' pieces    rep = ['   1 | 4 | 7' ; '   2 | 5 | 8' ; '   3 | 6 | 9'];     % Prompt user with options    fprintf('Welcome to Tic-Tac-Toe!\n')    nHumans = str2double(input('Enter the number of human players: ', 's'));    if isnan(nHumans) || ceil(nHumans) ~= nHumans || nHumans < 1 || nHumans > 2        nHumans = 0;        pHuman = false(2, 1);    elseif nHumans == 1        humanFirst = input('Would the human like to go first (Y/N)? ', 's');        if length(humanFirst) == 1 && lower(humanFirst) == 'n'            pHuman = [false ; true];        else            pHuman = [true ; false];        end    else        pHuman = true(2, 1);    end    if any('o' == input('Should Player 1 use X or O? ', 's'))        marks = 'OX';    else        marks = 'XO';    end    fprintf('So Player 1 is %shuman and %cs and Player 2 is %shuman and %cs.\n', ...        char('not '.*~pHuman(1)), marks(1), char('not '.*~pHuman(2)), marks(2))    if nHumans > 0        fprintf('Select the space to mark by entering the space number.\n')        fprintf('No entry will quit the game.\n')    end     % Play game    gameOver = false;    turn = 1;    while ~gameOver        fprintf('\n')        disp(rep)        fprintf('\n')        if pHuman(turn)            [move, isValid, isQuit] = GetMoveFromPlayer(turn, boards);            gameOver = isQuit;        else            move = GetMoveFromComputer(turn, boards);            fprintf('Player %d chooses %d\n', turn, move)            isValid = true;            isQuit = false;        end        if isValid && ~isQuit            [r, c] = ind2sub([3 3], move);            boards(r, c, turn) = true;            rep(r, 4*c) = marks(turn);            if CheckWin(boards(:, :, turn))                gameOver = true;                fprintf('\n')                disp(rep)                fprintf('\nPlayer %d wins!\n', turn)            elseif CheckDraw(boards)                gameOver = true;                fprintf('\n')                disp(rep)                fprintf('\nCat''s game!\n')            end            turn = ~(turn-1)+1;        end    endend function [move, isValid, isQuit] = GetMoveFromPlayer(pNum, boards)% move - 1-9 indicating move position, 0 if invalid move% isValid - logical indicating if move was valid, true if quitting% isQuit - logical indicating if player wishes to quit game    p1 = boards(:, :, 1);    p2 = boards(:, :, 2);    moveStr = input(sprintf('Player %d: ', pNum), 's');    if isempty(moveStr)        fprintf('Play again soon!\n')        move = 0;        isValid = true;        isQuit = true;    else        move = str2double(moveStr);        isQuit = false;        if isnan(move) || move < 1 || move > 9 || p1(move) || p2(move)            fprintf('%s is an invalid move.\n', moveStr)            isQuit = 0;            isValid = false;        else            isValid = true;        end    endend function move = GetMoveFromComputer(pNum, boards)% pNum - 1-2 player number% boards - 3x3x2 logical array where pBoards(:,:,1) is player 1's marks% Assumes that it is possible to make a move    if ~any(boards(:))     % Play in the corner for first move        move = 1;    else                    % Use Newell and Simon's "rules to win"        pMe = boards(:, :, pNum);        pThem = boards(:, :, ~(pNum-1)+1);        possMoves = find(~(pMe | pThem)).';         % Look for a winning move        move = FindWin(pMe, possMoves);        if move            return        end         % Look to block opponent from winning        move = FindWin(pThem, possMoves);        if move            return        end         % Look to create a fork (two non-blocked lines of two)        for m = possMoves            newPMe = pMe;            newPMe(m) = true;            if CheckFork(newPMe, pThem)                move = m;                return            end        end         % Look to make two in a row so long as it doesn't force opponent to fork        notGoodMoves = false(size(possMoves));        for m = possMoves            newPMe = pMe;            newPMe(m) = true;            if CheckPair(newPMe, pThem)                nextPossMoves = possMoves;                nextPossMoves(nextPossMoves == m) = [];                theirMove = FindWin(newPMe, nextPossMoves);                newPThem = pThem;                newPThem(theirMove) = true;                if ~CheckFork(newPThem, newPMe)                    move = m;                    return                else                    notGoodMoves(possMoves == m) = true;                end            end        end        possMoves(notGoodMoves) = [];         % Play the center if available        if any(possMoves == 5)            move = 5;        	return        end         % Play the opposite corner of the opponent's piece if available        corners = [1 3 7 9];        move = intersect(possMoves, ...            corners(~(pMe(corners) | pThem(corners)) & pThem(fliplr(corners))));        if ~isempty(move)            move = move(1);            return        end         % Play an empty corner if available        move = intersect(possMoves, corners);        if move            move = move(1);            return        end         % Play an empty side if available        sides = [2 4 6 8];        move = intersect(possMoves, sides);        if move            move = move(1);            return        end         % No good moves, so move randomly        possMoves = find(~(pMe | pThem));        move = possMoves(randi(length(possMoves)));    endend function move = FindWin(board, possMoves)% board - 3x3 logical representing one player's pieces% move - integer indicating position to move to win, or 0 if no winning move    for m = possMoves        newPMe = board;        newPMe(m) = true;        if CheckWin(newPMe)            move = m;            return        end    end    move = 0;end function win = CheckWin(board)% board - 3x3 logical representing one player's pieces% win - logical indicating if that player has a winning board    win = any(all(board)) || any(all(board, 2)) || ...        all(diag(board)) || all(diag(fliplr(board)));end function fork = CheckFork(p1, p2)% fork - logical indicating if player 1 has created a fork unblocked by player 2    fork = sum([sum(p1)-sum(p2) (sum(p1, 2)-sum(p2, 2)).' ...        sum(diag(p1))-sum(diag(p2)) ...        sum(diag(fliplr(p1)))-sum(diag(fliplr(p2)))] == 2) > 1;end function pair = CheckPair(p1, p2)% pair - logical indicating if player 1 has two in a line unblocked by player 2    pair = any([sum(p1)-sum(p2) (sum(p1, 2)-sum(p2, 2)).' ...        sum(diag(p1))-sum(diag(p2)) ...        sum(diag(fliplr(p1)))-sum(diag(fliplr(p2)))] == 2);end function draw = CheckDraw(boards)% boards - 3x3x2 logical representation of all players' pieces    draw = all(all(boards(:, :, 1) | boards(:, :, 2)));end`
Output:

Computer goes first and plays perfectly:

```Welcome to Tic-Tac-Toe!
Enter the number of human players: 1
Would the human like to go first (Y/N)? n
Should Player 1 use X or O? x
So Player 1 is not human and Xs and Player 2 is human and Os.
Select the space to mark by entering the space number.
No entry will quit the game.

1 | 4 | 7
2 | 5 | 8
3 | 6 | 9

Player 1 chooses 1

X | 4 | 7
2 | 5 | 8
3 | 6 | 9

Player 2: 4

X | O | 7
2 | 5 | 8
3 | 6 | 9

Player 1 chooses 2

X | O | 7
X | 5 | 8
3 | 6 | 9

Player 2: 3

X | O | 7
X | 5 | 8
O | 6 | 9

Player 1 chooses 5

X | O | 7
X | X | 8
O | 6 | 9

Player 2: 8

X | O | 7
X | X | O
O | 6 | 9

Player 1 chooses 9

X | O | 7
X | X | O
O | 6 | X

Player 1 wins!```

Computer goes first, but misses opportunity to set up for a fork, setting up human player instead:

```Welcome to Tic-Tac-Toe!
Enter the number of human players: 1
Would the human like to go first (Y/N)? n
Should Player 1 use X or O? x
So Player 1 is not human and Xs and Player 2 is human and Os.
Select the space to mark by entering the space number.
No entry will quit the game.

1 | 4 | 7
2 | 5 | 8
3 | 6 | 9

Player 1 chooses 1

X | 4 | 7
2 | 5 | 8
3 | 6 | 9

Player 2: 9

X | 4 | 7
2 | 5 | 8
3 | 6 | O

Player 1 chooses 2

X | 4 | 7
X | 5 | 8
3 | 6 | O

Player 2: 3

X | 4 | 7
X | 5 | 8
O | 6 | O

Player 1 chooses 6

X | 4 | 7
X | 5 | 8
O | X | O

Player 2: 7

X | 4 | O
X | 5 | 8
O | X | O

Player 1 chooses 5

X | 4 | O
X | X | 8
O | X | O

Player 2: 8

X | 4 | O
X | X | O
O | X | O

Player 2 wins!```

## mIRC Scripting Language

`alias ttt {  if (\$2 isin %ttt) || (!%ttt) {    var %ttt~ = \$remove(\$iif(%ttt,%ttt,1 2 3 4 5 6 7 8 9),\$2,X,O)    var %ttt~~ = \$replace(\$iif(%ttt,%ttt,1 2 3 4 5 6 7 8 9),\$2,X)    set %ttt \$replace(%ttt~~,\$iif((\$regex(%ttt~~,/(?:O . . (?:(?:. O .|O) . . (\d)|(?:. (\d) .|(\d)) . . O)|(\d) . . (?:. O .|O) . . O|. . (?:O . (?:O . (\d)|(\d) . O)|(\d) . O . O) . .)/)) || (\$regex(%ttt~~,/^(?:. . . )*(?:O (?:O (\d)|(\d) O)|(\d) O O)(?: . . .)*\$/)),\$regml(1),\$iif((\$regex(%ttt~~,/(?:X . . (?:(?:. X .|X) . . (\d)|(?:. (\d) .|(\d)) . . X)|(\d) . . (?:. X .|X) . . X|. . (?:X . (?:X . (\d)|(\d) . X)|(\d) . X . X) . .)/)) || (\$regex(%ttt~~,/^(?:. . . )*(?:X (?:X (\d)|(\d) X)|(\d) X X)(?: . . .)*\$/)),\$regml(1),\$iif(\$remove(%ttt~,2,4,6,8,\$chr(32)),\$iif((5 isin \$remove(%ttt~,2,4,6,8)) && (\$rand(0,\$numtok(\$v2,32)) == 0),5,\$gettok(\$remove(%ttt~,2,4,6,8),\$rand(1,\$numtok(\$remove(%ttt~,2,4,6,8),32)),32)),\$gettok(%ttt~,\$rand(1,\$numtok(%ttt~,32)),32)))),O)    tokenize 32 %ttt    if (\$regex(%ttt,/(?:X . . (?:X|. X .) . . X|. . X . X . X . .)/)) || (\$regex(%ttt,/^(?:. . . )*X X X(?: . . .)*\$/)) {      echo -ag \$me Wins      tokenize 32 %ttt~~      unset %ttt    }    elseif (\$regex(%ttt,/(?:O . . (?:O|. O .) . . O|. . O . O . O . .)/)) || (\$regex(%ttt,/^(?:. . . )*O O O(?: . . .)*\$/)) {      echo -ag \$me Loses      unset %ttt    }    elseif (!\$regex(%ttt,/\d/)) {      echo -ag Draw      unset %ttt    }    echo -ag � \$+ \$iif(\$1 isnum,\$chr(32),\$1) \$+ \$chr(124) \$+ \$iif(\$2 isnum,\$chr(32),\$2) \$+ \$chr(124) \$+ \$iif(\$3 isnum, ,\$3)    echo -ag � \$+ \$iif(\$4 isnum,\$chr(32),\$4) \$+ \$chr(124) \$+ \$iif(\$5 isnum,\$chr(32),\$5) \$+ \$chr(124) \$+ \$iif(\$6 isnum, ,\$6)    echo -ag � \$+ \$iif(\$7 isnum,\$chr(32),\$7) \$+ \$chr(124) \$+ \$iif(\$8 isnum,\$chr(32),\$8) \$+ \$chr(124) \$+ \$iif(\$9 isnum, ,\$9)  }  else {    echo -ag Place Taken    tokenize 32 %ttt    echo -ag � \$+ \$iif(\$1 isnum,\$chr(32),\$1) \$+ \$chr(124) \$+ \$iif(\$2 isnum,\$chr(32),\$2) \$+ \$chr(124) \$+ \$iif(\$3 isnum, ,\$3)    echo -ag � \$+ \$iif(\$4 isnum,\$chr(32),\$4) \$+ \$chr(124) \$+ \$iif(\$5 isnum,\$chr(32),\$5) \$+ \$chr(124) \$+ \$iif(\$6 isnum, ,\$6)    echo -ag � \$+ \$iif(\$7 isnum,\$chr(32),\$7) \$+ \$chr(124) \$+ \$iif(\$8 isnum,\$chr(32),\$8) \$+ \$chr(124) \$+ \$iif(\$9 isnum, ,\$9)  }}`

## Perl

A basic negamax search (with caching) is done to find the best move. If there are several equally good moves, one of them is selected randomly.

The computer player is not perfect, and so a human player can sometimes win.

This is not perl's fault, but mine; it ought to always be a tie, or a win for the computer. Anyone who can identify the mistake, is welcome to fix it.

`use warnings;use strict; my \$initial = join ",", qw(abc def ghi);my %reverse = qw(X O O X); # In list context, returns best move,# In scalar context, returns the score of best move.my %cache;sub best_move {	my (\$b, \$me) = @_;	if( exists \$cache{\$b,\$me,wantarray} ) {		return \$cache{\$b,\$me,wantarray};	} elsif( my \$s = score( \$b, \$me ) ) {		return \$cache{\$b,\$me,wantarray} = (wantarray ? undef : \$s);	}	my \$him = \$reverse{\$me};	my (\$best, @best) = (-999);	for my \$m (moves(\$b)) {		(my \$with_m = \$b) =~ s/\$m/\$me/ or die;		# The || operator supplies scalar context to best_move(...)		my \$s = -(score(\$with_m, \$him) || best_move(\$with_m, \$him));		if( \$s > \$best ) {			(\$best, @best) = (\$s, \$m);		} elsif( \$s == \$best ) {			push @best, \$m;		}	}	\$cache{\$b,\$me,wantarray} = wantarray ? \$best[rand @best] : \$best;} my \$winner = q[([XOxo])(?:\1\1|...\1...\1|..\1..\1|....\1....\1)];sub score {	my (\$b, \$me) = @_;	\$b =~ m/\$winner/o or return 0;	return \$1 eq \$me ? +1 : -1;} sub moves {	my (\$b) = @_;	\$b =~ /([^xoXO,\n])/g;} sub print_board {	my (\$b) = @_;	\$b =~ s/\B/|/g;	\$b =~ s/,/\n-+-+-\n/g;	print \$b, "\n";} sub prompt {	my (\$b, \$color) = @_;	my @moves = moves(\$b);	unless( @moves ) {		return;	}	while( 1 ) {		print "Place your \$color on one of [@moves]: ";		defined(my \$m = <>) or return;		chomp(\$m);		return \$m if grep \$m eq \$_, @moves;	}} my @players = (	{ whose => "your", name => "You",	  verb => "You place", get_move => \&prompt },	{ whose => "the computer's", name => "Computer",	  verb => "The computer places", get_move => \&best_move },);my \$whose_turn = int rand 2; my \$color = "X";my \$b = \$initial; while( 1 ) {	my \$p = \$players[\$whose_turn];	print_board(\$b);	print "It is \$p->{whose} turn.\n";	# The parens around \$m supply list context to the right side	# or the = operator, which causes sub best_move to return the	# best move, rather than the score of the best move.	my ( \$m ) = \$p->{get_move}->(\$b, \$color);	if( \$m ) {		print "\$p->{verb} an \$color at \$m\n";		\$b =~ s/\$m/\$color/;		my \$s = score(\$b, \$color) or next;		print_board(\$b);		print "\$p->{name} ", \$s > 0 ? "won!\n" : "lost!\n";	} else {		print "\$p->{name} cannot move.\n";	}	print "Game over.\nNew Game...\n";	(\$b, \$color, \$whose_turn) = (\$initial, "X", int rand 2);	redo;} continue {	\$color = \$reverse{\$color};	\$whose_turn = !\$whose_turn;} `
Output:
```a|b|c
-+-+-
d|e|f
-+-+-
g|h|i
Place your X on one of [a b c d e f g h i]: e
You place an X at e
a|b|c
-+-+-
d|X|f
-+-+-
g|h|i
It is the computer's turn.
The computer places an O at c
a|b|O
-+-+-
d|X|f
-+-+-
g|h|i
Place your X on one of [a b d f g h i]: a
You place an X at a
X|b|O
-+-+-
d|X|f
-+-+-
g|h|i
It is the computer's turn.
The computer places an O at f
X|b|O
-+-+-
d|X|O
-+-+-
g|h|i
Place your X on one of [b d g h i]: i
You place an X at i
X|b|O
-+-+-
d|X|O
-+-+-
g|h|X
You won!
Game over.
New Game...
a|b|c
-+-+-
d|e|f
-+-+-
g|h|i
Place your X on one of [a b c d e f g h i]:
```

## Perl 6

Works with: Rakudo version 2011.11

The computer plays a random game. Output is formatted in a similar way to that of the better python version.

` use v6; my @board = 1..9;my @winning-positions = [0..2], [3..5], [6..8], [0,3,6], [1,4,7], [2,5,8],	[0,4,8], [6,4,2]; sub get-winner() {	for @winning-positions {		return (@board[\$_][0], \$_) if [eq] @board[\$_];	}} sub free-indexes() {	@board.keys.grep: { @board[\$_] eq any(1..9) }} sub ai-move() {	given free-indexes.pick {		@board[\$_] = 'o';		say "I go at: { \$_ + 1 }\n";	}} sub print-board() {	say @board.map({ "\$^a | \$^b | \$^c" }).join("\n--+---+--\n"), "\n";} sub human-move() {	my \$pos = prompt "Choose one of { (free-indexes >>+>> 1).join(",") }: ";	if \$pos eq any(free-indexes >>+>> 1) {		@board[\$pos - 1] = 'x';	} else {		say "Sorry, you want to put your 'x' where?";		human-move();	}} for (&ai-move, &human-move) xx * {	print-board;	.();	last if get-winner() or not free-indexes;} if get-winner() -> (\$player, \$across) {	say "\$player wins across [", (\$across >>+>> 1).join(", "), "].";} else {	say "How boring, a draw!";} `

## Phix

AI copied from C. User goes first, as does loser. After a draw the start player alternates.

`sequence board = repeat(' ',9)  -- {' '/'X'/'O'} constant wins = {{1,2,3},{4,5,6},{7,8,9},{1,4,7},{2,5,8},{3,6,9},{1,5,9},{3,5,7}} function check_winner()    for w=1 to length(wins) do        integer {i,j,k} = wins[w],                boardi = board[i]        if boardi!=' ' and boardi=board[j] and boardi=board[k] then            return boardi        end if    end for    return 0end function procedure showboard()    printf(1," %c | %c | %c\n---+---+---\n %c | %c | %c\n---+---+---\n %c | %c | %c\n",board)end procedure integer best_ifunction test_move(integer val, integer depth)integer score = check_winner()integer best = -1, changed = 0    if score!=0 then return iff(score=val?1:-1) end if    for i=1 to 9 do        if board[i]=' ' then             {changed,board[i]} @= val            score = -test_move('O'+'X'-val, depth + 1)            board[i] = ' '            if score>best then                if depth=0 then                    best_i = i;                end if                best = score;            end if        end if    end for    return iff(changed!=0?best:0)end function integer user = 1 function game()integer key, k, win    board = repeat(' ',9)     printf(1,"Board postions are numbered so:\n1 2 3\n4 5 6\n7 8 9\n");    printf(1,"You have O, I have X.\n\n");    for n=1 to 9 do        if(user) then            printf(1,"your move: ");            while 1 do                key = wait_key()                if find(key,{#1B,'q','Q'}) then return "Quit" end if                k = key-'0'                if k>=1 and k<=9 and board[k]=' ' then                    board[k] = 'O'                    printf(1,"%c\n",key)                    exit                end if            end while        else            if n=1 then --/* randomize if computer opens, less boring */                best_i = rand(9)            else                {} = test_move('X', 0);            end if            board[best_i] = 'X'            printf(1," my move: %d\n", best_i);        end if        showboard();        user = 1-user        win = check_winner()        if win!=0 then            return iff(win=='O' ? "You win.\n\n" : "I win.\n\n");        end if    end for    return "A draw.\n\n";end function while 1 do    string res = game()    puts(1,res)    if res="Quit" then exit end ifend while`

Sample game (after a draw), with the boards cut/pasted into the horizontal

```Board postions are numbered so:
1 2 3
4 5 6
7 8 9
You have O, I have X.

my move: 5     your move: 2     my move: 1     your move: 9     my move: 4     your move: 6     my move: 7
|   |           | O |         X | O |         X | O |         X | O |         X | O |         X | O |
---+---+---     ---+---+---     ---+---+---     ---+---+---     ---+---+---     ---+---+---     ---+---+---
| X |           | X |           | X |           | X |         X | X |         X | X | O       X | X | O
---+---+---     ---+---+---     ---+---+---     ---+---+---     ---+---+---     ---+---+---     ---+---+---
|   |           |   |           |   |           |   | O         |   | O         |   | O       X |   | O
I win.

Board postions are numbered so:
1 2 3
4 5 6
7 8 9
You have O, I have X.

```

## PicoLisp

This solution doesn't bother about the game logic, but simply uses the alpha-beta-pruning 'game' function in the "simul" library.

`(load "@lib/simul.l")  # for 'game' function (de display ()   (for Y (3 2 1)      (prinl "   +---+---+---+")      (prin " " Y)      (for X (1 2 3)         (prin " | " (or (get *Board X Y) " ")) )      (prinl " |") )   (prinl "   +---+---+---+")   (prinl "     a   b   c") ) (de find3 (P)   (find      '((X Y DX DY)         (do 3            (NIL (= P (get *Board X Y)))            (inc 'X DX)            (inc 'Y DY)            T ) )      (1 1 1 1 2 3 1 1)      (1 2 3 1 1 1 1 3)      (1 1 1 0 0 0 1 1)      (0 0 0 1 1 1 1 -1) ) ) (de myMove ()   (when      (game NIL 8         '((Flg)     # Moves            (unless (find3 (or (not Flg) 0))               (make                  (for (X . L) *Board                     (for (Y . P) L                        (unless P                           (link                              (cons                                 (cons X Y (or Flg 0))                                 (list X Y) ) ) ) ) ) ) ) )         '((Mov) # Move            (set (nth *Board (car Mov) (cadr Mov)) (cddr Mov)) )         '((Flg)     # Cost            (if (find3 (or Flg 0)) -100 0) ) )      (let Mov (caadr @)         (set (nth *Board (car Mov) (cadr Mov)) 0) )      (display) ) ) (de yourMove (X Y)   (and      (sym? X)      (>= 3 (setq X (- (char X) 96)) 1)      (num? Y)      (>= 3 Y 1)      (not (get *Board X Y))      (set (nth *Board X Y) T)      (display) ) ) (de main ()   (setq *Board (make (do 3 (link (need 3)))))   (display) ) (de go Args   (cond      ((not (yourMove (car Args) (cadr Args)))         "Illegal move!" )      ((find3 T) "Congratulation, you won!")      ((not (myMove)) "No moves")      ((find3 0) "Sorry, you lost!") ) )`
Output:
```: (main)
+---+---+---+
3 |   |   |   |
+---+---+---+
2 |   |   |   |
+---+---+---+
1 |   |   |   |
+---+---+---+
a   b   c

: (go a 1)
+---+---+---+
3 |   |   |   |
+---+---+---+
2 |   |   |   |
+---+---+---+
1 | T |   |   |
+---+---+---+
a   b   c
+---+---+---+
3 |   |   |   |
+---+---+---+
2 |   | 0 |   |
+---+---+---+
1 | T |   |   |
+---+---+---+
a   b   c```

## Prolog

Works with SWI-Prolog.
Uses a minimax algorithm with no Alpha-beta pruning, as the max depth of the recursion is 8. Computer never loses.
A GUI interface written in XPCE is given.

`:- use_module('min-max.pl'). :-dynamic box/2.:- dynamic tic_tac_toe_window/1. % Computer begins.tic-tac-toe(computer) :-	V is random(9),	TTT = [_,_,_,_,_,_ ,_,_,_],	nth0(V, TTT, o),	display_tic_tac_toe(TTT). % Player beginstic-tac-toe(me) :-	TTT = [_,_,_,_,_,_ ,_,_,_],	display_tic_tac_toe(TTT).  display_tic_tac_toe(TTT) :-	retractall(box(_,_)),	retractall(tic_tac_toe_window(_)),	new(D, window('Tic-tac-Toe')),	send(D, size, size(170,170)),	X = 10, Y = 10,	display(D, X, Y, 0, TTT),	assert(tic_tac_toe_window(D)),	send(D, open). display(_, _, _, _, []). display(D, X, Y, N, [A,B,C|R]) :-	display_line(D, X, Y, N, [A,B,C]),	Y1 is Y+50,	N3 is N+3,	display(D, X, Y1, N3, R).  display_line(_, _, _, _, []).display_line(D, X, Y, N, [C|R]) :-	(   nonvar(C)-> C1 = C; C1 = ' '),	new(B, tic_tac_toe_box(C1)),	assertz(box(N, B)),	send(D, display, B, point(X, Y)),	X1 is X + 50,	N1 is N+1,	display_line(D, X1, Y, N1, R).   % class tic_tac_toe_box% display an 'x' when the player clicks% display an 'o' when the computer plays:- pce_begin_class(tic_tac_toe_box, box, "Graphical window with text"). variable(mess, any, both, "text to display"). initialise(P, Lbl) :->	send(P, send_super, initialise),	send(P, slot, mess, Lbl),	WS = 50, HS = 50,	send(P, size, size(WS,HS)),	send(P, recogniser,	     handler_group(new(click_gesture(left,					     '',					     single,					     message(@receiver, my_click))))). % the box is clickedmy_click(B) :->	send(B, set_val, x),	send(@prolog, play). % only works when the box is "free"set_val(B, Val) :->	get(B, slot, mess, ' '),	send(B, slot, mess, Val),	send(B, redraw),	send(B, flush).  %  redefined method to display custom graphical objects.'_redraw_area'(P, A:area) :->	send(P, send_super, '_redraw_area', A),	%we display the text	get(P, slot, mess, Lbl),	new(Str1, string(Lbl)),	get_object(P, area, area(X,Y,W,H)),	send(P, draw_box, X, Y, W, H),	send(P, draw_text, Str1,		font(times, normal, 30),		X, Y, W, H, center, center). :- pce_end_class. play :-	numlist(0, 8, L),	maplist(init, L, TTT),	finished(x, TTT, Val),	(   Val = 2 -> send(@display, inform,'You win !'),	               tic_tac_toe_window(D),		       send(D, destroy)	;   (	Val = 1 -> send(@display, inform,'Draw !'),	                   tic_tac_toe_window(D),		           send(D, destroy)	    ;	next_move(TTT, TT1),		maplist(display, L, TT1),		finished(o, TT1, V),		(   V = 2 -> send(@display, inform,'I win !'),			     tic_tac_toe_window(D),		             send(D, destroy)		;   (	V = 1 -> send(@display, inform,'Draw !'),		                 tic_tac_toe_window(D),			         send(D, destroy)		    ;	true)))).  % use minmax to compute the next movenext_move(TTT, TT1) :-	minimax(o, 0, 1024, TTT, _V1- TT1).  % we display the new boarddisplay(I, V) :-	nonvar(V),	box(I, V1),	send(V1, set_val, V). display(_I, _V). % we create the board for minmaxinit(I, V) :-	box(I, V1),	get(V1, slot, mess, V),	V \= ' '. init(_I, _V). % winning position for the player P ?winned(P, [A1, A2, A3, A4, A5, A6, A7, A8, A9]) :-       (is_winning_line(P, [A1, A2, A3]);	is_winning_line(P, [A4, A5, A6]);	is_winning_line(P, [A7, A8, A9]);	is_winning_line(P, [A1, A4, A7]);	is_winning_line(P, [A2 ,A5, A8]);	is_winning_line(P, [A3, A6, A9]);	is_winning_line(P, [A1, A5, A9]);	is_winning_line(P, [A3, A5, A7])).  is_winning_line(P, [A, B, C]) :-	nonvar(A), A = P,	nonvar(B), B = P,	nonvar(C), C = P. % Winning position for the playereval(Player, Deep, TTT, V) :-	winned(Player, TTT),	(   Player = o -> V is 1000 - 50 * Deep; V is -1000+ 50 * Deep). % Loosing position for the playereval(Player, Deep, TTT, V) :-	select(Player, [o,x], [Player1]),	winned(Player1, TTT),	(   Player = x -> V is 1000 - 50 * Deep; V is -1000+ 50 * Deep). % Draw positioneval(_Player, _Deep, TTT, 0) :-	include(var, TTT, []).  % we fetch the free positions of the boardpossible_move(TTT, LMove) :-	new(C, chain),	forall(between(0,8, I),	       (   nth0(I, TTT, X),		   (   var(X) -> send(C, append, I); true))),	chain_list(C, LMove). % we create the new position when the player P clicks% the box "N"assign_move(P, TTT, N, TT1) :-	copy_term(TTT, TT1),	nth0(N, TT1, P). % We fetch all the possible boards obtained from board TTT% for the player Pget_next(Player, Deep, TTT, Player1, Deep1, L):-	possible_move(TTT, LMove),	select(Player, [o,x], [Player1]),	Deep1 is Deep + 1,	maplist(assign_move(Player, TTT), LMove, L).  % The game is over ?% Player P winsfinished(P, TTT, 2) :-	winned(P, TTT). % Drawfinished(_P, TTT, 1) :-	include(var, TTT, []). % the game is not overfinished(_P, _TTT, 0) . % minmax must knows when the computer plays% (o for ordinateur in French)computer(o).  `

Module min-max.pl defines minimax algorithm.

`:- module('min-max.pl', [minimax/5]). % minimax(Player, Deep, MaxDeep, B, V-B)% @arg1 : current player at this level% @arg2 : current level of recursion% @arg3 : max level of recursion (in this version of the game no use : set to 1024 !)% @arg4 : current board% @arg5 : B is the evaluation of the board, the result is V-B to know the new board % Here we get an evaluationminimax(Player, Deep, MaxDeep, B, V-B) :-	(   eval(Player, Deep, B, V) -> true	; % in this version of the game this second division always fails	(   Deep > MaxDeep -> V is random(1000) - 1000)). % here we must compute all the possible moves to know the evaluation of the boardminimax(Player, Deep, MaxDeep, B, V) :-	get_next(Player, Deep, B, Player1, Deep1, L),	maplist(minimax(Player1, Deep1, MaxDeep), L, LV),	maplist(lie, L, LV, TLV),	sort(TLV, SLVTmp),	(   computer(Player) -> reverse(SLVTmp, SLV); SLV = SLVTmp),	SLV = [V | _R].  lie(TTT, V-_, V-TTT).  `

## Python

The computer enforces the rules but plays a random game.

` '''    Tic-tac-toe game player.    Input the index of where you wish to place your mark at your turn.''' import random board = list('123456789')wins = ((0,1,2), (3,4,5), (6,7,8),        (0,3,6), (1,4,7), (2,5,8),        (0,4,8), (2,4,6)) def printboard():    print('\n'.join(' '.join(board[x:x+3]) for x in(0,3,6))) def score():    for w in wins:        b = board[w[0]]        if b in 'XO' and all (board[i] == b for i in w):            return b, [i+1 for i in w]    return None, None def finished():    return all (b in 'XO' for b in board) def space():    return [ b for b in board if b not in 'XO'] def my_turn(xo):    options = space()    choice = random.choice(options)    board[int(choice)-1] = xo    return choice def your_turn(xo):    options = space()    while True:        choice = input(" Put your %s in any of these positions: %s "                       % (xo, ''.join(options))).strip()        if choice in options:            break        print( "Whoops I don't understand the input" )    board[int(choice)-1] = xo    return choice def me(xo='X'):    printboard()    print('I go at', my_turn(xo))    return score()    assert not s[0], "\n%s wins across %s" % s def you(xo='O'):    printboard()    # Call my_turn(xo) below for it to play itself    print('You went at', your_turn(xo))    return score()    assert not s[0], "\n%s wins across %s" % s  print(__doc__)while not finished():    s = me('X')    if s[0]:        printboard()        print("\n%s wins across %s" % s)        break    if not finished():        s = you('O')        if s[0]:            printboard()            print("\n%s wins across %s" % s)            breakelse:    print('\nA draw') `

Sample Game

```    Tic-tac-toe game player.
Input the index of where you wish to place your mark at your turn.

1 2 3
4 5 6
7 8 9
I go at 9
1 2 3
4 5 6
7 8 X
Put your O in any of these positions: 12345678 1
You went at 1
O 2 3
4 5 6
7 8 X
I go at 3
O 2 X
4 5 6
7 8 X
Put your O in any of these positions: 245678 4
You went at 4
O 2 X
O 5 6
7 8 X
I go at 2
O X X
O 5 6
7 8 X
Put your O in any of these positions: 5678 7
You went at 7
O X X
O 5 6
O 8 X

O wins across [1, 4, 7]```

### Better skilled player

In this version, The computer player will first complete a winning line of its own if it can, otherwise block a winning line of its opponent if they have two in a row, or then choose a random move.

` '''    Tic-tac-toe game player.    Input the index of where you wish to place your mark at your turn.''' import random board = list('123456789')wins = ((0,1,2), (3,4,5), (6,7,8),        (0,3,6), (1,4,7), (2,5,8),        (0,4,8), (2,4,6)) def printboard():    print('\n-+-+-\n'.join('|'.join(board[x:x+3]) for x in(0,3,6))) def score(board=board):    for w in wins:        b = board[w[0]]        if b in 'XO' and all (board[i] == b for i in w):            return b, [i+1 for i in w]    return None def finished():    return all (b in 'XO' for b in board) def space(board=board):    return [ b for b in board if b not in 'XO'] def my_turn(xo, board):    options = space()    choice = random.choice(options)    board[int(choice)-1] = xo    return choice def my_better_turn(xo, board):    'Will return a next winning move or block your winning move if possible'    ox = 'O' if xo =='X' else 'X'    oneblock = None    options  = [int(s)-1 for s in space(board)]    for choice in options:        brd = board[:]        brd[choice] = xo        if score(brd):            break        if oneblock is None:            brd[choice] = ox            if score(brd):                oneblock = choice    else:        choice = oneblock if oneblock is not None else random.choice(options)    board[choice] = xo    return choice+1 def your_turn(xo, board):    options = space()    while True:        choice = input("\nPut your %s in any of these positions: %s "                       % (xo, ''.join(options))).strip()        if choice in options:            break        print( "Whoops I don't understand the input" )    board[int(choice)-1] = xo    return choice def me(xo='X'):    printboard()    print('\nI go at', my_better_turn(xo, board))    return score() def you(xo='O'):    printboard()    # Call my_turn(xo, board) below for it to play itself    print('\nYou went at', your_turn(xo, board))    return score()  print(__doc__)while not finished():    s = me('X')    if s:        printboard()        print("\n%s wins along %s" % s)        break    if not finished():        s = you('O')        if s:            printboard()            print("\n%s wins along %s" % s)            breakelse:    print('\nA draw')`
Output:
```    Tic-tac-toe game player.
Input the index of where you wish to place your mark at your turn.

1|2|3
-+-+-
4|5|6
-+-+-
7|8|9

I go at 2
1|X|3
-+-+-
4|5|6
-+-+-
7|8|9

Put your O in any of these positions: 13456789 5

You went at 5
1|X|3
-+-+-
4|O|6
-+-+-
7|8|9

I go at 1
X|X|3
-+-+-
4|O|6
-+-+-
7|8|9

Put your O in any of these positions: 346789 3

You went at 3
X|X|O
-+-+-
4|O|6
-+-+-
7|8|9

I go at 7
X|X|O
-+-+-
4|O|6
-+-+-
X|8|9

Put your O in any of these positions: 4689 4

You went at 4
X|X|O
-+-+-
O|O|6
-+-+-
X|8|9

I go at 6
X|X|O
-+-+-
O|O|X
-+-+-
X|8|9

Put your O in any of these positions: 89 9

You went at 9
X|X|O
-+-+-
O|O|X
-+-+-
X|8|O

I go at 8

A draw```

## Racket

The program provides standard interface for implementation of any zero–sum game with perfect information such as tick-tack-toe, Nim, the 21 game etc. It is possible to create interactive players (as objects) with different playing strategy (AI-driven, user-driven, random etc.) and let them play with each other through message-sending technique.

The optimal strategy is implemented via lazy minimax algorythm with α-β-pruning and arbitrary depth of the recursion.

The program consists of separate modules:

```+ minimax.rkt    -- Written in Lazy Racket, implements the general minimax algorythm as
|                   given in Wikipedia.
V
+ game.rkt       -- Written in Lazy Racket, defines general classes for the game and players.
|                   turn-taking games with perfect information in general.
V
+ tick-tack.rkt  -- Written in Racket, implements the tick-tack-toe game.
```

The minimax.rkt module:

` #lang lazy(provide minimax) (define (minimax tree)  (! (let minimax ([node tree] [α -inf.0] [β +inf.0] [max-player #f])       (cond          [(number? node) node]         [(empty? node) 0.0]         [max-player          (let next ([x node] [α α])            (if (or (empty? x) (<= β α))                 α                (next (cdr x)                      (max α (minimax (car x) α β (not max-player))))))]         [else          (let next ([x node] [β β])            (if (or (empty? x) (<= β α))                 β                (next (cdr x)                      (min β (minimax (car x) α β (not max-player))))))])))) `

The game.rkt module:

` #lang lazy(require racket/class         "minimax.rkt"         (only-in racket/list shuffle argmax)) (provide game%         interactive-player         define-partners) ;;--------------------------------------------------------------------;; Class representing the logics and optimal strategy ;; for a zero-sum game with perfect information.(define game%  (class object%    (super-new)     ;; virtual methods which set up the game rules    (init-field my-win?         ; State -> Bool                my-loss?        ; State -> Bool                draw-game?      ; State -> Bool                my-move         ; State Move -> State                opponent-move   ; State Move -> State                possible-moves  ; State -> (list Move)                show-state)     ; State -> Any     ;; optimal-move :: State -> Move    ;; Choses the optimal move.     ;; If several equivalent moves exist -- choses one randomly.    (define/public ((optimal-move look-ahead) S)      (! (argmax (λ (m) (! (minimax (game-tree S m look-ahead))))                 (shuffle (possible-moves S)))))     ;; game-tree :: State -> (Move -> (Treeof Real))    (define (game-tree S m look-ahead)      (let new-ply ([moves (cycle opponent-move my-move)]                     [i 1]                     [s (my-move S m)])        (cond          [(my-win? s)        (/  1 i)] ; more close wins and loses          [(my-loss? s) (/ -1 i)] ; have bigger weights          [(draw-game? s)     0]          [(>= i look-ahead)  (/ 1 i)]           [else (map (λ (x) (new-ply (cdr moves) (+ 1 i) ((car moves) s x)))                     (possible-moves s))])))     ;; make-move :: State (State -> Move) -> (Move State Symbol)    (define/public (make-move S move)      (cond        [(my-loss? S)   (values '() S 'loss)]                 [(draw-game? S) (values '() S 'draw)]           [else (let* ([m* (! (move S))]                     [S* (my-move S m*)])                (cond                  [(my-win? S*)    (values m* S* 'win)]                   [(draw-game? S*) (values m* S* 'draw)]                  [else            (values m* S* 'next)]))])))) ;;--------------------------------------------------------------------;; Mixin representing an interactive game player.;; The parameter `game` defines a game which is played.(define (interactive-player game)  (class game    (super-new)     (inherit-field show-state)    (inherit make-move optimal-move)     (init-field name                [look-ahead 4]                [opponent 'undefined]                [move-method (optimal-move look-ahead)])     (define/public (your-turn S)      (define-values (m S* status) (make-move S move-method))      (! (printf "\n~a makes move ~a\n" name m))      (! (show-state S*))      (! (case status           ['stop (displayln "The game was interrupted.")]           ['win  (printf "~a wins!" name)]           ['loss (printf "~a wins!" name)]           ['draw (printf "Draw!")]           [else (send opponent your-turn S*)])))))  ;;--------------------------------------------------------------------;; a simple macro for initialization of game partners(define-syntax-rule   (define-partners game (A #:win A-wins #:move A-move)                         (B #:win B-wins #:move B-move))  (begin    (define A (class game                 (super-new                  [my-win?  A-wins]                 [my-loss? B-wins]                 [my-move  A-move]                 [opponent-move B-move])))    (define B (class game                 (super-new                  [my-win?  B-wins]                 [my-loss? A-wins]                 [my-move  B-move]                 [opponent-move A-move]))))) ;;--------------------------------------------------------------------;; the main procedure which initiates the game(define (start-game p1 p2 initial-state)  (set-field! opponent p1 p2)  (set-field! opponent p2 p1)  (send p1 your-turn initial-state)) `

The tick-tack.rkt module:

`#lang racket (require "game.rkt"         racket/set         lazy/force) ;;--------------------------------------------------------------------;; Tick-tack-toe game implementation ;; the structure representing a board(struct board (x o)) ;; sets of X's and O's(define xs board-x)(define os board-o) (define empty-board (board (set) (set))) (define all-cells  (set '(1 1) '(1 2) '(1 3)       '(2 1) '(2 2) '(2 3)       '(3 1) '(3 2) '(3 3))) (define (free-cells b)  (set-subtract all-cells (xs b) (os b))) (define winning-positions  (list (set '(1 1) '(2 2) '(3 3))        (set '(1 3) '(2 2) '(3 1))        (set '(1 1) '(1 2) '(1 3))        (set '(2 1) '(2 2) '(2 3))        (set '(3 1) '(3 2) '(3 3))        (set '(1 1) '(2 1) '(3 1))        (set '(1 2) '(2 2) '(3 2))        (set '(1 3) '(2 3) '(3 3)))) ;; a predicate for winning state on the board(define ((wins? s) b)  (ormap (curryr subset? (s b)) winning-positions)) ;; player moves(define (x-move b m)  (board (set-add (xs b) m) (os b)))(define (o-move b m)  (board (xs b) (set-add (os b) m))) ;; textual representation of the board(define (show-board b)  (for ([i '(3 2 1)])    (printf "~a " i)    (for ([j '(1 2 3)])      (display (cond                 [(set-member? (os b) (list j i)) "|o"]                 [(set-member? (xs b) (list j i)) "|x"]                 [else "| "])))    (display "|\n"))  (display "   1 2 3    ")) ;;--------------------------------------------------------------------;; The definition of the game;; general properties(define tic-tac%  (class game%    (super-new     [draw-game?       (compose set-empty? free-cells)]     [possible-moves   (compose set->list free-cells)]     [show-state       show-board]))) ;; players(define-partners tic-tac%  (x% #:win (wins? xs) #:move x-move)  (o% #:win (wins? os) #:move o-move)) ;; Computer players(define player-A (new (interactive-player x%) [name "A"] [look-ahead 6])) (define player-B (new (interactive-player o%) [name "B"] [look-ahead 6])) ; The interactive user(define User   (new (interactive-player x%)        [name "User"]       [move-method         (λ (b) (let make-move ([m (read)])                 (match m                   ['q (exit)]                   [(list (or 1 2 3) (or 1 2 3)) m]                   [else (make-move (read))])))])) ;; The dummy player plays randomly(define Dummy   (new (interactive-player o%) [name "Dummy"] [look-ahead 0]))  `

Sample games:

Computer plays with the computer:

```> (!(start-game player-A player-B empty-board))

A makes move (3 1)
3 | | | |
2 | | | |
1 | | |x|
1 2 3
B makes move (2 2)
3 | | | |
2 | |o| |
1 | | |x|
1 2 3
A makes move (1 1)
3 | | | |
2 | |o| |
1 |x| |x|
1 2 3
B makes move (2 1)
3 | | | |
2 | |o| |
1 |x|o|x|
1 2 3
A makes move (2 3)
3 | |x| |
2 | |o| |
1 |x|o|x|
1 2 3
B makes move (3 2)
3 | |x| |
2 | |o|o|
1 |x|o|x|
1 2 3
A makes move (1 2)
3 | |x| |
2 |x|o|o|
1 |x|o|x|
1 2 3
B makes move (1 3)
3 |o|x| |
2 |x|o|o|
1 |x|o|x|
1 2 3
A makes move (3 3)
3 |o|x|x|
2 |x|o|o|
1 |x|o|x|
1 2 3    Draw!
```

Computer plays with the dummy:

```> (!(start-game player-A Dummy empty-board))

A makes move (3 1)
3 | | | |
2 | | | |
1 | | |x|
1 2 3
Dummy makes move (2 3)
3 | |o| |
2 | | | |
1 | | |x|
1 2 3
A makes move (1 1)
3 | |o| |
2 | | | |
1 |x| |x|
1 2 3
Dummy makes move (3 3)
3 | |o|o|
2 | | | |
1 |x| |x|
1 2 3
A makes move (2 1)
3 | |o|o|
2 | | | |
1 |x|x|x|
1 2 3    A wins!
```

User plays with the dummy:

```> (!(start-game Dummy User empty-board))

Dummy makes move (2 3)
3 | |o| |
2 | | | |
1 | | | |
1 2 3    (1 2)

User makes move (1 2)
3 | |o| |
2 |x| | |
1 | | | |
1 2 3
Dummy makes move (3 2)
3 | |o| |
2 |x| |o|
1 | | | |
1 2 3    (1 3)

User makes move (1 3)
3 |x|o| |
2 |x| |o|
1 | | | |
1 2 3
Dummy makes move (3 3)
3 |x|o|o|
2 |x| |o|
1 | | | |
1 2 3    (1 1)

User makes move (1 1)
3 |x|o|o|
2 |x| |o|
1 |x| | |
1 2 3    User wins!
```

As an example of another zero-sum game consider the classical Nim game:

` #lang racket (require "game.rkt"         lazy/force) ;;--------------------------------------------------------------------;; The definition of the game (define initial-state '(3 5 7)) (define (move s m) (map - s m)) (define (win? s) (= 1 (apply + s))) (define (show-state s) (displayln (map (λ (n) (make-list n '●)) s))) (define (possible-moves S)  (append-map    (λ (heap n)      (map (λ (x) (map (curry * x) heap))          (range 1 (+ 1 (min 3 n)))))   '((1 0 0) (0 1 0) (0 0 1)) S)) (define Nim% (class game%               (super-new                [draw-game?       (const #f)]                [possible-moves   possible-moves]                [show-state       show-state]))) (define-partners Nim%  (first%  #:win win? #:move move)  (second% #:win win? #:move move)) ;; players(define player-A   (new (interactive-player first%) [name "A"] [look-ahead 4])) (define player-B   (new (interactive-player second%) [name "B"] [look-ahead 4])) `

Computer plays with the computer:

```> (!(start-game player-A player-B initial-state))

A makes move (0 0 2)
((● ● ●) (● ● ● ● ●) (● ● ● ● ●))

B makes move (1 0 0)
((● ●) (● ● ● ● ●) (● ● ● ● ●))

A makes move (2 0 0)
(() (● ● ● ● ●) (● ● ● ● ●))

B makes move (0 2 0)
(() (● ● ●) (● ● ● ● ●))

A makes move (0 3 0)
(() () (● ● ● ● ●))

B makes move (0 0 1)
(() () (● ● ● ●))

A makes move (0 0 3)
(() () (●))
A wins!
```

With use of memoization it is easy to train automatic players so that they would never lose and play very fast.

## REXX

This REXX program uses an analytical solution instead of hard-fast choices.

Options used within the REXX program:

•   a (single) numbered grid is used instead of coördinates for easier marker placement
•   straight lines (wins) are handled dynamically instead of hard-coding them
•   allows the human player to specify any   NxN   size tic─tac─toe board   (a square grid)
•   allows the human player to specify who plays first   (default is the user)
•   allows the human player to specify what markers (symbols) to be used (can use hex pairs)
•   allows the human player to quit (exit) the game at any time
•   allows the human player to win   (if the human goes first   and   makes a certain move)

A fair amount of code was dedicated to error detection and the presentation of the tic-tac-toe grids.

`/*REXX program plays  (with a human)  the   tic─tac─toe   game  on an  NxN  grid.       */\$=copies('─', 9)                                 /*eyecatcher literal for error messages*/oops =\$ '***error*** ';    cell@ ="cell number"  /*a couple of literals for some  SAYs. */sing='│─┼';    jam="║";    bar='═';     junc="╬";         dbl=jam || bar || juncsw=linesize() - 1                                /*obtain width of the terminal (less 1)*/parse arg N hm cm .,@.                           /*obtain optional arguments from the CL*/if N=='' | N==","  then N=3;   oN=N              /*N  not specified?   Then use default.*/N=abs(N);   NN=N*N;   middle=NN%2+N%2            /*if N < 0,  then computer goes first. */if N<2  then do; say oops  'tic─tac─toe grid is too small: '  N;     exit;   endpad=left('', sw%NN)                              /*display padding:  6x6  in 80 columns.*/if hm=='' then hm="X";  if cm==''  then cm="O"   /*define  the markers:  Human, computer*/hm=aChar(hm,'human');   cm=aChar(cm,'computer')  /*process/define markers for players.  */parse upper value hm cm with uh uc               /*use uppercase values is markers:  X x*/if uh==uc  then cm=word('O X', 1 + (uh=="O") )   /*The human wants Hal's marker?  Swap. */if oN<0 then call Hmove middle                   /*Hal moves first? Then choose middling*/        else call showGrid                       /*showGrid also checks for wins & draws*/                            do  forever          /*'til the cows come home  (or  QUIT). */                            call CBLF            /*process carbon-based lifeform's move.*/                            call Hal             /*determine Hal's  (the computer) move.*/                            end   /*forever*/    /*showGrid subroutine does wins & draws*//*──────────────────────────────────────────────────────────────────────────────────────*/ab:    parse arg bx; if bx\==' '  then return bx /*test if the  marker  isn't  a  blank.*/       say oops 'character code for'     whoseX     "marker can't be a blank."       exit                                      /*stick a fork in it,  we're all done. *//*──────────────────────────────────────────────────────────────────────────────────────*/aChar: parse arg x,whoseX;  L=length(x)                               /*process markers.*/       if L==1                   then return ab(x)                    /*1 char,  as is. */       if L==2 & datatype(x,'X') then return ab(x2c(x))               /*2 chars, hex.   */       if L==3 & datatype(x,'W') then return ab(d2c(x))               /*3 chars, decimal*/       say oops 'illegal character or character code for'  whoseX  "marker: "   x       exit                                      /*stick a fork in it,  we're all done. *//*──────────────────────────────────────────────────────────────────────────────────────*/CBLF : prompt='Please enter a'    cell@    "to place your next marker ["hm']   (or Quit):'         do forever;   say \$ prompt;     parse pull x 1 ux 1 ox;    upper ux         if datatype(ox,'W') then ox=ox/1        /*maybe normalize cell number:  +0007. */           select           when abbrev('QUIT',ux,1) then call tell 'quitting.'           when x=''                then iterate                     /*Nada?  Try again.*/           when words(x)\==1        then say oops "too many" cell#  'specified:'   x           when \datatype(x,'N')    then say oops cell@   "isn't numeric: "        x           when \datatype(x,'W')    then say oops cell@  "isn't an integer: "      x           when x=0                 then say oops cell@  "can't be zero: "         x           when x<0                 then say oops cell@  "can't be negative: "     x           when x>NN                then say oops cell@  "can't exceed "           NN           when @.ox\==''           then say oops cell@  "is already occupied: "   x           otherwise                leave  /*forever*/           end   /*select*/         end     /*forever*/       @.ox=hm                                   /*place a marker for the human (CLBF). */       call showGrid                             /*and display the  tic─tac─toe  grid.  */       return/*──────────────────────────────────────────────────────────────────────────────────────*/Hal:           select                                        /*Hal tries various moves. */               when win(cm,N-1)   then call Hmove , ec       /*is this the winning move?*/               when win(hm,N-1)   then call Hmove , ec       /* "   "   a blocking   "  */               when @.middle==''  then call Hmove middle     /*pick the  center  move.  */               when @.N.N==''     then call Hmove , N N      /*bottom right corner move.*/               when @.N.1==''     then call Hmove , N 1      /*   "    left    "     "  */               when @.1.N==''     then call Hmove , 1 N      /*  top  right    "     "  */               when @.1.1==''     then call Hmove , 1 1      /*   "    left    "     "  */               otherwise               call Hmove , ac       /*pick a  blank  cell   "  */               end   /*select*/       return/*──────────────────────────────────────────────────────────────────────────────────────*/Hmove: parse arg Hplace,dr dc;    if Hplace==''  then Hplace = (dr-1)*N  +  dc       @.Hplace=cm                                           /*place computer's marker. */       say;  say  \$   'computer places a marker  ['cm"]  at"     cell@      ' '     Hplace       call showGrid       return/*──────────────────────────────────────────────────────────────────────────────────────*/showGrid: _=0;   open=0;    cW=5;    cH=3                    /*cell width,  cell height.*/           do r=1 for N;  do c=1 for N; _=_+1; @.r.c=@._; open=open|@._==''; end           end   /*r*/       say                                                   /* [↑]  create grid coörds.*/       z=0;          do     j=1  for  N                      /* [↓]  show grids&markers.*/                       do   t=1  for cH;    _=;  __=         /*MK is a marker in a cell.*/                         do k=1  for  N;    if t==2  then z=z+1;      mk=;    c#=                         if t==2  then do;  mk=@.z;  c#=z;  end      /*c# is cell number*/                         _= _||jam||center(mk,cW);   __= __ || jam || center(c#, cW)                         end   /*k*/                       say pad substr(_,2) pad translate(substr(__,2), sing,dbl)                       end     /*t*/                     if j==N  then leave;  _=                       do b=1  for  N;    _=_ || junc || copies(bar, cW);  end  /*b*/                     say pad  substr(_,2)  pad  translate(substr(_,2), sing, dbl)                     end        /*j*/       say       if win(hm)  then  call tell  'You  ('hm")  won!"       if win(cm)  then  call tell  'The computer  ('cm")  won."       if \open    then  call tell  'This tic─tac─toe game is a draw.'       return/*──────────────────────────────────────────────────────────────────────────────────────*/tell:    do 4; say; end;     say center(' 'arg(1)" ", sw, '─');     do 5; say; end;   exit/*──────────────────────────────────────────────────────────────────────────────────────*/win:   parse arg wm,w;    if w==''  then w=N             /*see if there are W of markers*/      ac=; do   r=1  for N;  _=0;  ec=                   /*see if any  rows are a winner*/             do c=1  for N;  _=_+ (@.r.c==wm);   if @.r.c==''  then ec=r c;   end           if ec\=='' then ac=ec;  if _==N | (_>=w & ec\=='')  then return 1           end   /*r*/                                   /*w=N-1?  Checking for near win*/           do   c=1  for N;  _=0; ec=                    /*see if any  cols are a winner*/             do r=1  for N;  _=_+ (@.r.c==wm);   if @.r.c==''  then ec=r c;   end           if ec\=='' then ac=ec;  if _==N | (_>=w & ec\=='')  then return 1           end   /*r*/                                   /*EC is a R,C version of cell #*/      _=0; ec=                                           /*A winning descending diag. ? */           do d=1  for N;        _=_+ (@.d.d==wm);  if @.d.d=='' then ec=d d; end      if _==N | (_>=w & ec\=='')  then return 1      _=0; ec=; r=0                                      /*A winning ascending diagonal?*/           do c=N for N by -1; r=r+1; _=_+ (@.r.c==wm);  if @.r.c=='' then ec=r c           end   /*r*/      if _==N | (_>=w & ec\=='')  then return 1      return 0`

This REXX program makes use of   LINESIZE   REXX program (or BIF) which is used to determine the screen width (or linesize) of the terminal (console).

The   LINESIZE.REX   REXX program is included here   ──►   LINESIZE.REX.

output   when using the input of:   -3
(a negative   3   indicates a grid of   3x3   and that the computer should play first.)

Note:   the user input is shown along with the program output.

```───────── computer places a marker  [O]  at cell number   5

║     ║                              │     │
║     ║                           1  │  2  │  3
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║  O  ║                           4  │  5  │  6
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║     ║                           7  │  8  │  9
║     ║                              │     │

───────── Please enter a cell number to place your next marker [X]   (or Quit):
2         ◄■■■■■■■■■■ human player's move.

║     ║                              │     │
║  X  ║                           1  │  2  │  3
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║  O  ║                           4  │  5  │  6
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║     ║                           7  │  8  │  9
║     ║                              │     │

───────── computer places a marker  [O]  at cell number   9

║     ║                              │     │
║  X  ║                           1  │  2  │  3
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║  O  ║                           4  │  5  │  6
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║     ║  O                        7  │  8  │  9
║     ║                              │     │

───────── Please enter a cell number to place your next marker [X]   (or Quit):
1         ◄■■■■■■■■■■ human player's move.

║     ║                              │     │
X  ║  X  ║                           1  │  2  │  3
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║  O  ║                           4  │  5  │  6
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║     ║  O                        7  │  8  │  9
║     ║                              │     │

───────── computer places a marker  [O]  at cell number   3

║     ║                              │     │
X  ║  X  ║  O                        1  │  2  │  3
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║  O  ║                           4  │  5  │  6
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║     ║  O                        7  │  8  │  9
║     ║                              │     │

───────── Please enter a cell number to place your next marker [X]   (or Quit):
7         ◄■■■■■■■■■■ human player's move.

║     ║                              │     │
X  ║  X  ║  O                        1  │  2  │  3
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║  O  ║                           4  │  5  │  6
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
X  ║     ║  O                        7  │  8  │  9
║     ║                              │     │

───────── computer places a marker  [O]  at cell number   6

║     ║                              │     │
X  ║  X  ║  O                        1  │  2  │  3
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
║  O  ║  O                        4  │  5  │  6
║     ║                              │     │
═════╬═════╬═════                    ─────┼─────┼─────
║     ║                              │     │
X  ║     ║  O                        7  │  8  │  9
║     ║                              │     │

────────────────────────────── The computer  (O)  won. ──────────────────────────────
```

output   when using the input of:   5   db
(which indicates a grid of   5x5   and that the marker for the human is a hexadecimal   db   [█].)

```         ║     ║     ║     ║               │     │     │     │
║     ║     ║     ║            1  │  2  │  3  │  4  │  5
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║            6  │  7  │  8  │  9  │ 10
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║           11  │ 12  │ 13  │ 14  │ 15
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║           16  │ 17  │ 18  │ 19  │ 20
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║           21  │ 22  │ 23  │ 24  │ 25
║     ║     ║     ║               │     │     │     │

───────── Please enter a cell number to place your next marker [█]   (or Quit):
5         ◄■■■■■■■■■■ human player's move.

║     ║     ║     ║               │     │     │     │
║     ║     ║     ║  █         1  │  2  │  3  │  4  │  5
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║            6  │  7  │  8  │  9  │ 10
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║           11  │ 12  │ 13  │ 14  │ 15
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║           16  │ 17  │ 18  │ 19  │ 20
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║           21  │ 22  │ 23  │ 24  │ 25
║     ║     ║     ║               │     │     │     │

───────── computer places a marker  [O]  at cell number  14

║     ║     ║     ║               │     │     │     │
║     ║     ║     ║  █         1  │  2  │  3  │  4  │  5
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║            6  │  7  │  8  │  9  │ 10
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║  O  ║           11  │ 12  │ 13  │ 14  │ 15
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║           16  │ 17  │ 18  │ 19  │ 20
║     ║     ║     ║               │     │     │     │
═════╬═════╬═════╬═════╬═════     ─────┼─────┼─────┼─────┼─────
║     ║     ║     ║               │     │     │     │
║     ║     ║     ║           21  │ 22  │ 23  │ 24  │ 25
║     ║     ║     ║               │     │     │     │

───────── Please enter a cell number to place your next marker [█]   (or Quit):
q         ◄■■■■■■■■■■ human player's response.

────────────────────────────────── quitting. ──────────────────────────────────
```

## Ring

Easy and simple implementation of tecTacToe in ring programming language with human-human type of game(for now).

This implementation is a gui implementation using the default gui provided by the language

The tecTacToe.ring is provided here

` Load "guilib.ring" #Provide a list to save each button status in numeric readable format#0=nothing 1=X 2=Olst=[] #Provide onScreen button status and stylebtns=[] #Define who has the turnisXTurn=true      app=new qApp    {         frmMain=new qMainWindow()		{			setWindowTitle("TicTacToe!")			resize(300,320)			move(200,200)			//buttons			pos=0			for y=0 to 2				for x=0 to 2				//Creating Buttons on the screen					pos++					Add(lst,0)					Add(btns,new qPushButton(frmMain)						{							setGeometry(x*100,y*100,100,100)							setText("-")							setclickevent("Disp(" + pos +")")							setstylesheet("font-size:24pt ; font: bold ; color:yellow ; background-color: green")						})				next            next			//StatusBar			status=new qStatusBar(frmMain)			{                showMessage("Ready",0)            }			setwindowflags(Qt_dialog)			setStatusbar(status)			show()        }		exec()	} //Restart the game by re init buttons statusfunc reStart    for i=1 to 9        lst[i]=0        btns[i].setText("-")    next  isXTurn=true func Disp x    if isXTurn=true and lst[x]=0		btns[x].setText("X")		lst[x]=1		isXTurn=false	but isXTurn=false and lst[x]=0        btns[x].setText("O")        lst[x]=2        isXTurn=true    ok 	winner = CheckWinner()	#if there is no Winner and still there is ability to winner	#continue playing.	if winner<1 return ok 	//Who is the winner!    switch winner        on 1            new qMessagebox(frmMain)            {				SetWindowTitle("We have a winner!")                SetText("Good job X you won!")                show()            }        on 2			new qMessagebox(frmMain)            {				SetWindowTitle("We have a winner!")                SetText("Good job O you won!")                show()            }        on 3            new qMessagebox(frmMain)            {                SetWindowTitle("Oh no it's a tie")                SetText("Oh no it's a tie!")                show()            }    off    reStart() func CheckWinner        //vertical check        for v=1 to 9 step 3            if lst[v]!=0 and lst[v+1]!=0 and lst[v+2]!=0				if lst[v]=lst[v+1] and lst[v+1]=lst[v+2]                    return lst[v]                ok            ok        next        //horzintal        for h=1 to 3            if lst[h]!=0 and lst[h+3]!=0 and lst[h+6]!=0                if lst[h]=lst[h+3] and lst[h+3]=lst[h+6]                    return lst[h]                ok            ok        next        //Cross        if lst[1]!=0 and lst[5]!=0 and lst[9]!=0            if lst[1]=lst[5] and lst[5]=lst[9] return lst[1] ok        ok        if lst[3]!=0 and lst[5]!=0 and lst[7]!=0            if lst[3]=lst[5] and lst[5]=lst[7] return lst[3] ok        ok        //tie        tie=true        for i=1 to 9            if lst[i]=0 tie=false exit ok        next        if tie=true return 3 ok return 0 `
Output:

[image]

## Ruby

This implementation splits functionality into four classes: `Game`, `Player`, `HumanPlayer`, and `ComputerPlayer`. A game can be played between any combination of `HumanPlayer`s and `ComputerPlayer`s.

The AI for the computer uses certain heuristics to ensure that it never loses, but the AI is not as aggressive as it could be. The AI defends against the opening corner trap, but does not exploit it in its offense.

This implementation stores the board as a one-dimensional array and hardcodes all possible straight lines in `LINES`, rather than storing the board as a two-dimensional matrix and identifying straight lines dynamically.

`require 'set' module TicTacToe  LINES = [[1,2,3],[4,5,6],[7,8,9],[1,4,7],[2,5,8],[3,6,9],[1,5,9],[3,5,7]]   class Game    def initialize(player_1_class, player_2_class)      @board = Array.new(10) # we ignore index 0 for convenience       @current_player_id = 0      @players = [player_1_class.new(self, "X"), player_2_class.new(self, "O")]      puts "#{current_player} goes first."    end    attr_reader :board, :current_player_id     def play      loop do        place_player_marker(current_player)         if player_has_won?(current_player)          puts "#{current_player} wins!"          print_board          return        elsif board_full?          puts "It's a draw."          print_board          return        end         switch_players!      end    end     def free_positions      Set.new((1..9).select {|position| @board[position].nil?})    end     def place_player_marker(player)      position = player.select_position!      puts "#{player} selects #{player.marker} position #{position}"      @board[position] = player.marker    end     def player_has_won?(player)      LINES.any? do |line|        line.all? {|position| @board[position] == player.marker}      end    end     def board_full?      free_positions.empty?    end     def other_player_id      1 - @current_player_id    end     def switch_players!      @current_player_id = other_player_id    end     def current_player      @players[current_player_id]    end     def opponent      @players[other_player_id]    end     def turn_num      10 - free_positions.size    end     def print_board      col_separator, row_separator = " | ", "--+---+--"      label_for_position = lambda{|position| @board[position] ? @board[position] : position}       row_for_display = lambda{|row| row.map(&label_for_position).join(col_separator)}      row_positions = [[1,2,3], [4,5,6], [7,8,9]]      rows_for_display = row_positions.map(&row_for_display)      puts rows_for_display.join("\n" + row_separator + "\n")    end  end   class Player    def initialize(game, marker)      @game = game      @marker = marker    end    attr_reader :marker  end   class HumanPlayer < Player    def select_position!      @game.print_board      loop do        print "Select your #{marker} position: "        selection = gets.to_i        return selection if @game.free_positions.include?(selection)        puts "Position #{selection} is not available. Try again."      end    end     def to_s      "Human"    end  end   class ComputerPlayer < Player    DEBUG = false # edit this line if necessary     def group_positions_by_markers(line)      markers = line.group_by {|position| @game.board[position]}      markers.default = []      markers    end     def select_position!      opponent_marker = @game.opponent.marker       winning_or_blocking_position = look_for_winning_or_blocking_position(opponent_marker)      return winning_or_blocking_position if winning_or_blocking_position       if corner_trap_defense_needed?        return corner_trap_defense_position(opponent_marker)      end       # could make this smarter by sometimes doing corner trap offense       return random_prioritized_position    end     def look_for_winning_or_blocking_position(opponent_marker)      for line in LINES        markers = group_positions_by_markers(line)        next if markers[nil].length != 1        if markers[self.marker].length == 2          log_debug "winning on line #{line.join}"          return markers[nil].first        elsif markers[opponent_marker].length == 2          log_debug "could block on line #{line.join}"          blocking_position = markers[nil].first        end      end      if blocking_position        log_debug "blocking at #{blocking_position}"        return blocking_position      end    end     def corner_trap_defense_needed?      corner_positions = [1, 3, 7, 9]      opponent_chose_a_corner = corner_positions.any?{|pos| @game.board[pos] != nil}      return @game.turn_num == 2 && opponent_chose_a_corner    end     def corner_trap_defense_position(opponent_marker)      # if you respond in the center or the opposite corner, the opponent can force you to lose      log_debug "defending against corner start by playing adjacent"      # playing in an adjacent corner could also be safe, but would require more logic later on      opponent_position = @game.board.find_index {|marker| marker == opponent_marker}      safe_responses = {1=>[2,4], 3=>[2,6], 7=>[4,8], 9=>[6,8]}      return safe_responses[opponent_position].sample    end     def random_prioritized_position      log_debug "picking random position, favoring center and then corners"      ([5] + [1,3,7,9].shuffle + [2,4,6,8].shuffle).find do |pos|        @game.free_positions.include?(pos)      end    end     def log_debug(message)      puts "#{self}: #{message}" if DEBUG    end     def to_s      "[email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */_player_id}"    end  endend include TicTacToe Game.new(ComputerPlayer, ComputerPlayer).playputsplayers_with_human = [HumanPlayer, ComputerPlayer].shuffleGame.new(*players_with_human).play`
Output:
```Computer0 goes first.
Computer0 selects X position 5
Computer1 selects O position 9
Computer0 selects X position 3
Computer1 selects O position 7
Computer0 selects X position 8
Computer1 selects O position 2
Computer0 selects X position 1
Computer1 selects O position 4
Computer0 selects X position 6
It's a draw.
X | O | X
--+---+--
O | X | X
--+---+--
O | X | O

Human goes first.
1 | 2 | 3
--+---+--
4 | 5 | 6
--+---+--
7 | 8 | 9
Human selects X position 3
Computer1 selects O position 6
1 | 2 | X
--+---+--
4 | 5 | O
--+---+--
7 | 8 | 9
Human selects X position 7
Computer1 selects O position 5
1 | 2 | X
--+---+--
4 | O | O
--+---+--
X | 8 | 9
Human selects X position 4
Computer1 selects O position 1
O | 2 | X
--+---+--
X | O | O
--+---+--
X | 8 | 9
Human selects X position 9
Computer1 selects O position 8
O | 2 | X
--+---+--
X | O | O
--+---+--
X | O | X
Human selects X position 2
It's a draw.
O | X | X
--+---+--
X | O | O
--+---+--
X | O | X```

## Run BASIC

`' ---------------------------'  TIC TAC TOE' ---------------------------winBox\$ = "123 456 789 159 147 258 369 357"boxPos\$ = "123 231 456 564 789 897 159 591 357 753 132 465 798 174 285 396 159 471 582 693 147 258 369 195 375"ai\$     = "519628374"ox\$     = "OX" [newGame]for i = 1 to 9 box\$(i) = ""next igoto [shoTic] [loop]for j = 1 to 2 tic\$ = mid\$(ox\$,j,1) for i = 1 to 25  b\$	= word\$(boxPos\$,i," ")  b1	= val(mid\$(b\$,1,1))  b2	= val(mid\$(b\$,2,1))  b3	= val(mid\$(b\$,3,1))  if box\$(b1) = tic\$ AND box\$(b2) = tic\$ AND box\$(b3) = "" then     box\$(b3)  = "O"     goto [shoTic] end if next inext jif box\$(1) = "O" AND box\$(5) = "X" and box\$(9) = "X" then if box\$(3) = "" then   box\$(3) = "O"   goto [shoTic] end if if box\$(7) = "" then   box\$(7) = "O"   goto [shoTic] end ifend iffor i = 1 to 9 b1 = val(mid\$(ai\$,i,1)) if box\$(b1) = "" then   box\$(b1)  = "O"   exit for end ifnext i [shoTic]cls' ----------------------------------------' show tic tac toe screen' ----------------------------------------html "<table border=1 width=300px height=225px><TR>"for i = 1 to 9  html "<td align=center width=33%><h1>"    if box\$(i) <> "" then      html box\$(i)    else    button #box, " ";box\$(i);" ", [doTic]           #box  setkey(str\$(i))    end if    if i mod 3 = 0 then html "</tr><tr>"next ihtml "</table>"gosub [checkWin]wait [doTic]box\$(val(EventKey\$)) = "X"turn          = 1gosub [checkWin]goto [loop] ' --- check for a winner ----------[checkWin]for i = 1 to 8 b\$ = word\$(winBox\$,i," ") b1 = val(mid\$(b\$,1,1)) b2 = val(mid\$(b\$,2,1)) b3 = val(mid\$(b\$,3,1)) if box\$(b1) = "O" and box\$(b2) = "O" and box\$(b3) = "O" then   print "You Lose!"   goto [playAgain] end if if box\$(b1) = "X" and box\$(b2) = "X" and box\$(b3) = "X" then   print "You Win!"   goto [playAgain] end ifnext i moveCount = 0for i = 1 to 9 if box\$(i) <> "" then moveCount = moveCount + 1 next iif moveCount = 9 then  print "Draw!"  goto [playAgain]end ifRETURN [playAgain]input "Play again (y/n)";p\$if upper\$(p\$) = "Y" then goto [newGame]end`

## Scala

Functional implementation.

Computer vs. human. Human starts. Computer plays 'O' and human plays 'X'. Computer moves are legal, but random.

`package object tictactoe {  val Human = 'X'  val Computer = 'O'    val BaseBoard = ('1' to '9').toList  val WinnerLines = List((0,1,2), (3,4,5), (6,7,8), (0,3,6), (1,4,7), (2,5,8), (0,4,8), (2,4,6))  val randomGen = new util.Random(System.currentTimeMillis)} package tictactoe { class Board(aBoard : List[Char] = BaseBoard) {   def availableMoves = aBoard.filter(c => c != Human && c != Computer)   def availableMovesIdxs = for ((c,i) <- aBoard.zipWithIndex if c != Human && c != Computer) yield i   def computerPlays = new Board(aBoard.updated(availableMovesIdxs(randomGen.nextInt(availableMovesIdxs.length)), Computer))   def humanPlays(move : Char) = new Board(aBoard.updated(aBoard.indexOf(move), Human))   def isDraw = aBoard.forall(c => c == Human || c == Computer)   def isWinner(winner : Char) =     WinnerLines.exists{case (i,j,k) => aBoard(i) == winner && aBoard(j) == winner && aBoard(k) == winner}   def isOver = isWinner(Computer) || isWinner(Human) || isDraw   def print {     aBoard.grouped(3).foreach(row => println(row(0) + " " + row(1) + " " + row(2)))   }   def printOverMessage {     if (isWinner(Human)) println("You win.")    else if (isWinner(Computer)) println("Computer wins.")    else if (isDraw) println("It's a draw.")    else println("Not over yet, or something went wrong.")       } }  object TicTacToe extends Application {       def play(board : Board, turn : Char) {     // Reads a char from input until it is one of    // the available moves in the current board    def readValidMove() : Char = {      print("Choose a move: ")      val validMoves = board.availableMoves      val move = readChar      if (validMoves.contains(move)) {        move      } else {        println("Invalid move. Choose another one in " + validMoves)        readValidMove()      }    }      board.print         if (board.isOver) {      board.printOverMessage      return    }     if (turn == Human) { // Human plays                  val nextBoard = board.humanPlays(readValidMove)            play(nextBoard, Computer)    } else { // Computer plays      println("Computer plays: ")       val nextBoard = board.computerPlays       play(nextBoard, Human)    }      }      play(new Board(),Human) } }`
Output:
(human is always first)
```1 2 3
4 5 6
7 8 9
Choose a move: 1
X 2 3
4 5 6
7 8 9
Computer plays:
X 2 O
4 5 6
7 8 9
Choose a move: 3
Invalid move. Choose another one in List(2, 4, 5, 6, 7, 8, 9)
Choose a move: 4
X 2 O
X 5 6
7 8 9
Computer plays:
X 2 O
X 5 6
7 8 O
Choose a move: 7
X 2 O
X 5 6
X 8 O
You win.```

## Scilab

Can be a game of human v. human, human v. machine, or machine v. machine. Machine moves have a hierarchy: firstly, it looks for a winning move; secondly, it looks for a way to block the opponent's victory; lastly, it makes a random move.

`function [] = startGame()    //Board size and marks    N = 3;    marks = ["X" "O"];     //Creating empty board    board = string(zeros(N,N));    for i = 1:(N*N)        board(i) = "";    end     //Initialising players    clc();    players= [%F %F];    players = playerSetup(marks);     //Console header    header = [strsplit(marks(1)+" is ----")';...              strsplit(marks(2)+" is ----")'];    for i = 1:2        if players(i) then            header(i,6:10) = strsplit("P"+string(i)+".  ");        else            header(i,6:10) = strsplit("COMP.");        end    end     //Game loop    sleep(1000);    win_flag = %F;    count = 0;    while count<N*N        //Clear console, and print header and board        clc();        printf("%s\n %s\n",strcat(header(1,:)),strcat(header(2,:)));        dispBoard(board);         //Find which player should move        player_n = modulo(count,2) + 1;         if players(player_n) == %T then            //Human plays            pos = [];            valid_move = %F;            disp(marks(player_n)+"''s turn.");            while valid_move ~= %T                [pos,valid_move] = readHumanMove(board);                if ~valid_move then                    disp("You should input a valid cell number.");                end            end             if valid_move then                board = updateBoard(board,pos,marks(player_n));            else                error("Invalid move.");            end        else            //Computer plays            disp("Computer is playing.");            board = ComputerMove(board,marks(player_n),marks);            sleep(800);        end         //Count number of movements        count = count + 1;         //Check if the game has finished        [win_flag,winning_mark] = detectWin(board)        if win_flag then            break        end    end     //Clear screen at the end of game    clc();    disp("Game finished:");    dispBoard(board);     //Print results    if win_flag then        disp(winning_mark+" won!");    else        disp("It''s a tie.");    end     //Play again?    play_again = "";    while play_again ~= "Y" & play_again ~= "N"        play_again = input("Would you like to play again? (Y/N)","s");        play_again = strsplit(play_again);        play_again = convstr(play_again(1),"u");         if play_again ~= "Y" & play_again ~= "N" then            disp("Invalid answer.");        end    end     if play_again == "Y" then        startGame();    else        disp("Quit game.");    endendfunction function players = playerSetup(marks)    //Determines who plays which mark    players = [%F %F]; //True for human, Flase for computer     printf("\n%s always starts.\n",marks(1));    for i = 1:2        user_input = "";        while user_input ~= "Y" & user_input ~= "N"            user_input = input("Would you like to play as "+marks(i)+"? (Y/N)","s");            user_input = strsplit(user_input);            user_input = convstr(user_input(1),"u");             if user_input ~= "Y" & user_input ~= "N" then                disp("Invalid answer.");            end        end         //Print choice        if user_input == "Y" then            players(i) = %T;            printf("%s shall be player %d (P%d).\n\n",marks(i),i,i);        else            printf("%s shall be the computer (COMP).\n\n",marks(i));        end    endendfunction function [] = dispBoard(board)    //Print ASCII board on console     //Get board marks    marks = [" " " "];    mark_inds = find(board ~= "");    if mark_inds ~= [] then        marks(1) = board(mark_inds(1));        mark_inds = find( (board ~= "") & (board ~= marks(1)) );        if mark_inds ~= [] then            marks(2) = board(mark_inds(1));        end    end     //Transpose to display for humans    //[compatibility with readHumanMove()]    disp_board = board';     rows = 3*size(board,'r');    cols = 4*size(board,'c');    ascii_board = string(zeros(rows, cols));     mark_1=[...    strsplit("   |")';...    strsplit(" "+marks(1)+" |")';...    strsplit("___|")'];     mark_2=[...    strsplit("   |")';...    strsplit(" "+marks(2)+" |")';...    strsplit("___|")'];     Blank_mark=[...    strsplit("   |")';...    strsplit("   |")';...    strsplit("___|")'];     for r = ([1:size(board,'r')] - 1 )        for c = ([1:size(board,'c')] - 1)            if disp_board(r+1,c+1) == marks(1) then                ascii_board((r*3 + 1):((r+1)*3),...                            (c*4 + 1):((c+1)*4)) = mark_1;            elseif disp_board(r+1,c+1) == marks(2) then                ascii_board((r*3 + 1):((r+1)*3),...                            (c*4 + 1):((c+1)*4)) = mark_2;            else                ascii_board((r*3 + 1):((r+1)*3),...                            (c*4 + 1):((c+1)*4)) = Blank_mark;            end        end    end     for i = 1:cols        if modulo(i,4)>0 then            ascii_board(rows,i) = " ";        end    end     for i = 1:rows        ascii_board(i,cols) = " ";    end     printf("\n");    for i = 1:size(ascii_board,'r')        printf("%s\n",strcat(ascii_board(i,:)))    endendfunction function moves_board = availableMoves(board)    //Find empty cells on the board    moves_board = board;     for i = 1:(size(board,'r')*size(board,'c'))        if board(i) == "" then            moves_board(i) = string(i);        else            moves_board(i) = "_";        end    endendfunction function varargout = readHumanMove(board)    //Read human input    printf("\nAvailable cells:");    moves_board = availableMoves(board);    disp(moves_board');     x = input("\nEnter a move (0 to quit game): ");     valid = %F;    pos = 0;    total = size(moves_board,'r') * size(moves_board,'c');     //Check if it is a valid move    if x == 0 then        disp("Quit game.")        abort    elseif (x>=1 & x<=total) then        if (moves_board(x) == string(x)) then            valid = %T;            pos = x;        end    end     varargout = list(pos,valid);endfunction function varargout = updateBoard(board,pos,player)    //Add move to the board    if board(pos) ~= "" then        error('Error: Invalid move.');    end     board(pos) = player     varargout = list(board);endfunction function varargout = detectWin(board)    //Detect if there is a winner or not    win_flag = %F;    winner = "";     //Get board marks    marks = ["" ""];    mark_inds = find(board ~= "");    marks(1) = board(mark_inds(1))    mark_inds = find( (board ~= "") & (board ~= marks(1)) );    marks(2) = board(mark_inds(1));     //If there is a minimum number of moves, check if there is a winner    n_moves = find(~(board == ""));    n_moves = length(n_moves)     if n_moves >= size(board,'r') then        board_X = (board == marks(1));        board_O = (board == marks(2));          for i = 1:size(board,'r')            //Check rows            if find(~board_X(i,:)) == [] then                win_flag = %T;                winner = marks(1);                break            end            if find(~board_O(i,:)) == [] then                win_flag = %T;                winner = marks(2);                break            end             //Check columns            if find(~board_X(:,i)) == [] then                win_flag = %T;                winner = marks(1);                break            end            if find(~board_O(:,i)) == [] then                win_flag = %T;                winner = marks(2);                break            end        end         //Check diagonal        if ~win_flag then            if find(~diag(board_X)) == [] then                win_flag = %T;                winner = marks(1);            elseif find(~diag(board_O)) == [] then                win_flag = %T;                winner = marks(2);            end        end         //Check anti-diagonal        if ~win_flag then            board_X = board_X(:,\$:-1:1);            board_O = board_O(:,\$:-1:1);             if find(~diag(board_X)) == [] then                win_flag = %T;                winner = marks(1);            elseif find(~diag(board_O)) == [] then                win_flag = %T;                winner = marks(2);            end        end    end     varargout = list(win_flag,winner)endfunction function threat_pos = findThreat(board,player)    //Returns a list of moves that can finish the game     //Available moves    move_inds = find(~( availableMoves(board) == "_" ));     //If there is a minimum number of moves, check if there is a threat    threat_pos = [];    if (size(board,'r')*size(board,'c')) - length(move_inds) >...       (size(board,'r') - 1) then        for i = 1:length(move_inds)            temp_board = updateBoard(board,move_inds(i),player);            [win_flag,winner] = detectWin(temp_board);            if win_flag & winner == player then                threat_pos = [threat_pos move_inds(i)];            end        end    endendfunction function varargout = ComputerMove(board,mark,all_marks)    //Atomatically add a move to the board with no human input     //Find winning moves moves    move_inds = findThreat(board,mark);     //If there are no winning moves, find opponent's winning moves    //to block opponent's victory    if move_inds == [] then        if mark == all_marks(1) then            opponent = all_marks(2);        elseif mark == all_marks(2) then            opponent = all_marks(1);        end         move_inds = findThreat(board,opponent);    end     //If there are no winning moves or threats, find all possible moves    if move_inds == [] then        move_inds = find(~( availableMoves(board) == "_" ));    end     //Choose a random move among the selected possible moves    pos = grand(1,"prm",move_inds);    pos = pos(1);     //Update board by adding a new mark    board(pos) = mark;     varargout = list(board);    endfunction startGame()`

## Swift

Some Basic AI for obvious losing and winning conditions

` import Darwin enum Token : CustomStringConvertible {	case cross, circle 	func matches(tokens: [Token?]) -> Bool {		for token in tokens {			guard let t = token, t == self else { 				return false 			}		}		return true	} 	func emptyCell(in tokens: [Token?]) -> Int? {		if tokens[0] == nil 		&& tokens[1] == self 		&& tokens[2] == self {			return 0		} else		if tokens[0] == self 		&& tokens[1] == nil 		&& tokens[2] == self {			return 1		} else		if tokens[0] == self 		&& tokens[1] == self 		&& tokens[2] == nil {			return 2		}		return nil	} 	var description: String {		switch self {			case .cross: return "x" 			case .circle: return "o"		}	}} struct Board {	var cells: [Token?] = [nil, nil, nil, nil, nil, nil, nil, nil, nil] 	func cells(atCol col: Int) -> [Token?] {		return [cells[col], cells[col + 3], cells[col + 6]]	} 	func cells(atRow row: Int) -> [Token?] {		return [cells[row * 3], cells[row * 3 + 1], cells[row * 3 + 2]]	} 	func cellsTopLeft() -> [Token?] {		return [cells[0], cells[4], cells[8]]	} 	func cellsBottomLeft() -> [Token?] {		return [cells[6], cells[4], cells[2]]	} 	func winner() -> Token? {		let r0 = cells(atRow: 0)		let r1 = cells(atRow: 1)		let r2 = cells(atRow: 2)		let c0 = cells(atCol: 0)		let c1 = cells(atCol: 1)		let c2 = cells(atCol: 2)		let tl = cellsTopLeft()		let bl = cellsBottomLeft() 		if Token.cross.matches(tokens: r0)		|| Token.cross.matches(tokens: r1)		|| Token.cross.matches(tokens: r2)		|| Token.cross.matches(tokens: c0)		|| Token.cross.matches(tokens: c1)		|| Token.cross.matches(tokens: c2)		|| Token.cross.matches(tokens: tl)		|| Token.cross.matches(tokens: bl) {			return .cross		} else 		if Token.circle.matches(tokens: r0)		|| Token.circle.matches(tokens: r1)		|| Token.circle.matches(tokens: r2)		|| Token.circle.matches(tokens: c0)		|| Token.circle.matches(tokens: c1)		|| Token.circle.matches(tokens: c2)		|| Token.circle.matches(tokens: tl)		|| Token.circle.matches(tokens: bl) {			return .circle		}		return nil	} 	func atCapacity() -> Bool {		return cells.filter { \$0 == nil }.count == 0	} 	mutating func play(token: Token, at location: Int) {		cells[location] = token	} 	func findBestLocation(for player: Token) -> Int? {		let r0 = cells(atRow: 0)		let r1 = cells(atRow: 1)		let r2 = cells(atRow: 2)		let c0 = cells(atCol: 0)		let c1 = cells(atCol: 1)		let c2 = cells(atCol: 2)		let tl = cellsTopLeft()		let bl = cellsBottomLeft() 		if let cell = player.emptyCell(in: r0) {			return cell		} else if let cell = player.emptyCell(in: r1) {			return cell + 3		} else if let cell = player.emptyCell(in: r2) {			return cell + 6		} else if let cell = player.emptyCell(in: c0) {			return cell * 3		} else if let cell = player.emptyCell(in: c1) {			return cell * 3 + 1		} else if let cell = player.emptyCell(in: c2) {			return cell * 3 + 2		} else if let cell = player.emptyCell(in: tl) {			return cell == 0 ? 0 : (cell == 1 ? 4 : 8)		} else if let cell = player.emptyCell(in: bl) {			return cell == 0 ? 6 : (cell == 1 ? 4 : 2)		}		return nil	} 	func findMove() -> Int {		let empties = cells.enumerated().filter { \$0.1 == nil }		let r = Int(arc4random()) % empties.count		return empties[r].0	}} extension Board : CustomStringConvertible {	var description: String {		var result = "\n---------------\n"		for (idx, cell) in cells.enumerated() {			if let cell = cell {				result += "| \(cell) |"			} else {				result += "| \(idx) |"			} 			if (idx + 1) % 3 == 0 {				result += "\n---------------\n"			}		}		return result	}} while true {	var board = Board()	print("Who do you want to play as ('o' or 'x'): ", separator: "", terminator: "")	let answer = readLine()?.characters.first ?? "x" 	var player: Token = answer == "x" ? .cross : .circle	var pc: Token = player == .cross ? .circle : .cross 	print(board) 	while true {		print("Choose cell to play on: ", separator: "", terminator: "")		var pos = Int(readLine() ?? "0") ?? 0		while !board.atCapacity() && board.cells[pos] != nil {			print("Invalid move. Choose cell to play on: ", separator: "", terminator: "")			pos = Int(readLine() ?? "0") ?? 0		} 		if board.atCapacity() {			print("Draw")			break		} 		board.play(token: player, at: pos)		print(board) 		if let winner = board.winner() {			print("winner is \(winner)")			break		} else if board.atCapacity() {			print("Draw")			break		} 		if let win = board.findBestLocation(for: pc) {			board.play(token: pc, at: win)		} else if let def = board.findBestLocation(for: player) {			board.play(token: pc, at: def)		} else {			board.play(token: pc, at: board.findMove())		} 		print(board) 		if let winner = board.winner() {			print("winner is \(winner)")			break		}	}} `
Output:
```Who do you want to play as ('o' or 'x'): x

---------------
| 0 || 1 || 2 |
---------------
| 3 || 4 || 5 |
---------------
| 6 || 7 || 8 |
---------------

Choose cell to play on: 4

---------------
| 0 || 1 || 2 |
---------------
| 3 || x || 5 |
---------------
| 6 || 7 || 8 |
---------------

---------------
| o || 1 || 2 |
---------------
| 3 || x || 5 |
---------------
| 6 || 7 || 8 |
---------------

Choose cell to play on: 6

---------------
| o || 1 || 2 |
---------------
| 3 || x || 5 |
---------------
| x || 7 || 8 |
---------------

---------------
| o || 1 || o |
---------------
| 3 || x || 5 |
---------------
| x || 7 || 8 |
---------------

Choose cell to play on: 1

---------------
| o || x || o |
---------------
| 3 || x || 5 |
---------------
| x || 7 || 8 |
---------------

---------------
| o || x || o |
---------------
| 3 || x || 5 |
---------------
| x || o || 8 |
---------------

Choose cell to play on: 5

---------------
| o || x || o |
---------------
| 3 || x || x |
---------------
| x || o || 8 |
---------------

---------------
| o || x || o |
---------------
| o || x || x |
---------------
| x || o || 8 |
---------------

Choose cell to play on: 8

---------------
| o || x || o |
---------------
| o || x || x |
---------------
| x || o || x |
---------------

Draw
Who do you want to play as ('o' or 'x'):
```

## Tcl

Translation of: Python
`package require Tcl 8.6 # This code splits the players from the core game engineoo::class create TicTacToe {    variable board player letter who    constructor {player1class player2class} {	set board {1 2 3 4 5 6 7 8 9}	set player(0) [\$player1class new [self] [set letter(0) "X"]]	set player(1) [\$player2class new [self] [set letter(1) "O"]]	set who 0    }     method PrintBoard {} {	lassign \$board a1 b1 c1 a2 b2 c2 a3 b3 c3	puts [format " %s | %s | %s" \$a1 \$b1 \$c1]	puts "---+---+---"	puts [format " %s | %s | %s" \$a2 \$b2 \$c2]	puts "---+---+---"	puts [format " %s | %s | %s" \$a3 \$b3 \$c3]    }     method WinForSomeone {} {	foreach w {	    {0 1 2} {3 4 5} {6 7 8} {0 3 6} {1 4 7} {2 5 8} {0 4 8} {2 4 6}	} {	    set b [lindex \$board [lindex \$w 0]]	    if {\$b ni "X O"} continue	    foreach i \$w {if {[lindex \$board \$i] ne \$b} break}	    if {[lindex \$board \$i] eq \$b} {		foreach p \$w {lappend w1 [expr {\$p+1}]}		return [list \$b \$w1]	    }	}	return ""    }     method status {} {	return \$board    }     method IsDraw {} {	foreach b \$board {if {[string is digit \$b]} {return false}}	return true    }     method legalMoves {} {	foreach b \$board {if {[string is digit \$b]} {lappend legal \$b}}	return \$legal    }     method DoATurn {} {	set legal [my legalMoves]	my PrintBoard	while 1 {	    set move [\$player(\$who) turn]	    if {\$move in \$legal} break	    puts "Illegal move!"	}	lset board [expr {\$move - 1}] \$letter(\$who)	\$player(\$who) describeMove \$move	set who [expr {1 - \$who}]	return [my WinForSomeone]    }     method game {} {        puts "    Tic-tac-toe game player.    Input the index of where you wish to place your mark at your turn.\n"	while {![my IsDraw]} {	    set winner [my DoATurn]	    if {\$winner eq ""} continue	    lassign \$winner winLetter winSites	    my PrintBoard	    puts "\n\$winLetter wins across \[[join \$winSites {, }]\]"	    return \$winLetter	}	puts "\nA draw"    }} # Stupid robotic playeroo::class create RandomRoboPlayer {    variable g    constructor {game letter} {	set g \$game    }    method turn {} {	set legal [\$g legalMoves]	return [lindex \$legal [expr {int(rand()*[llength \$legal])}]]    }    method describeMove {move} {	puts "I go at \$move"    }} # Interactive human player delegateoo::class create HumanPlayer {    variable g char    constructor {game letter} {	set g \$game	set char \$letter    }    method turn {} {	set legal [\$g legalMoves]	puts ">>> Put your \$char in any of these positions: [join \$legal {}]"	while 1 {	    puts -nonewline ">>> "	    flush stdout	    gets stdin number	    if {\$number in \$legal} break	    puts ">>> Whoops I don't understand the input!"	}	return \$number    }    method describeMove {move} {	puts "You went at \$move"    }} # Assemble the piecesset ttt [TicTacToe new HumanPlayer RandomRoboPlayer]\$ttt game`

Sample game:

```    Tic-tac-toe game player.
Input the index of where you wish to place your mark at your turn.

1 | 2 | 3
---+---+---
4 | 5 | 6
---+---+---
7 | 8 | 9
>>> Put your X in any of these positions: 123456789
>>> 1
You went at 1
X | 2 | 3
---+---+---
4 | 5 | 6
---+---+---
7 | 8 | 9
I go at 5
X | 2 | 3
---+---+---
4 | O | 6
---+---+---
7 | 8 | 9
>>> Put your X in any of these positions: 2346789
>>> 7
You went at 7
X | 2 | 3
---+---+---
4 | O | 6
---+---+---
X | 8 | 9
I go at 9
X | 2 | 3
---+---+---
4 | O | 6
---+---+---
X | 8 | O
>>> Put your X in any of these positions: 23468
>>> 4
You went at 4
X | 2 | 3
---+---+---
X | O | 6
---+---+---
X | 8 | O

X wins across [1, 4, 7]
```

## XPL0

`\The computer marks its moves with an "O" and the player uses an "X". The\ numeric keypad is used to make the player's move.\\                         7 | 8 | 9\                        ---+---+---\                         4 | 5 | 6\                        ---+---+---\                         1 | 2 | 3\\The player always goes first, but the 0 key is used to skip a move. Thus\ it can be used to let the computer play first. Esc terminates program. inc     c:\cxpl\codes;  \intrinsic routine declarationsdef     X0=16, Y0=10;   \coordinates of character in upper-left squareint     I0,        PMove,          \player's move (^0..^9)        Key;            \keystrokeint     X, O;           \bit arrays for player and computer                        \ bit 0 corresponds to playing square 1, etc.  proc    HLine(X, Y);    \Draw a horizontal lineint     X, Y;int     I;[Cursor(X, Y);for I:= 0 to 10 do ChOut(0, ^Ä);];      \HLine  proc    VLine(X, Y);    \Draw a vertical line over the above horizontal lineint     X, Y;int     I;[for I:= 0 to 4 do        [Cursor(X, Y+I);        ChOut(0, if I&1 then ^Å else ^³);        ];];      \VLine  func    Won(p);         \Return 'true' if player P has wonint     P;int     T, I;[T:= [\$007, \$038, \$1C0, \$049, \$092, \$124, \$111, \$054];for I:= 0 to 7 do       \check if player matches a bit pattern for 3 in a row    if (P & T(I)) = T(I) then return true;return false;];      \Won  func    Cats;           \Return 'true' if no more moves available (Cat's game)[if (X ! O) = \$1FF then \all bit positions played        [Cursor(17, 20);        Text(0, "A draw!");        return true;        ];return false;];      \Cats  proc    DoMove(P, M, Ch); \Make move in player's bit array and display itint     P,              \address of player's bit array        M,              \index 0..8 where bit is placed        Ch;int     I, X, Y;[P(0):= P(0) ! 1<<M;    \make move I:= M / 3;              \display moveX:= Rem(0) * 4;Y:= (2-I) * 2;Cursor(X+X0, Y+Y0);ChOut(0, Ch);];      \DoMove  func    Try(P);         \Return the value of the best node for player Pint     P;              \address of player's bit arrayint     P1, I, I0, V, V0;[P1:= if P = addr X then addr O else addr X; if Won(P1(0)) then return -1;if (X ! O) = \$1FF then return 0; V0:= -1;                                \assume the worstfor I:= 0 to 8 do                       \for all of the squares...    if ((O!X) & 1<<I) = 0 then          \if square is unused        [P(0):= P(0) ! 1<<I;            \make tenative move        V:= -(extend(Try(P1)));         \get value        if V > V0 then                  \save best value                [V0:= V;  I0:= I];        P(0):= P(0) & ~(1<<I);          \undo tenative move        ];return V0 & \$FF ! I0<<8;];      \Try  proc    PlayGame;       \Play one game[ChOut(0, \$0C\FF\);     \clear screen with a form feedHLine(X0-1, Y0+1);      \draw grid (#)HLine(X0-1, Y0+3);VLine(X0+2, Y0);VLine(X0+6, Y0); X:= 0;  O:= 0;          \initialize player's bit arrays to emptyloop    [loop   [PMove:= ChIn(1);               \GET PLAYER'S MOVE (X)                if PMove = \$1B\Esc\ then                        [SetVid(3);  exit];     \restore display and end program                if PMove = ^0 then quit;                if PMove>=^1 & PMove<=^9 &      \check for legal move                   ((X!O) & 1<<(PMove-^1)) = 0 then quit;                ChOut(0, 7\Bel\);               \beep the dude                ];        if PMove # ^0 then                [DoMove(addr X, PMove-^1, ^X);                if Won(X) then                        [Cursor(17, 20);                        Text(0, "X wins!");                        quit;                        ];                ];        if Cats then quit;         I0:= Try(addr O) >>8;                   \GET COMPUTER'S MOVE (O)        DoMove(addr O, I0, ^O);                 \do best move        if Won(O) then                [Cursor(17, 20);                Text(0, "O wins!");                quit;                ];        if Cats then quit;        ];];      \PlayGame  int     CpuReg;[SetVid(1);                             \set 40x25 text modeCpuReg:= GetReg;                        \turn off annoying flashing cursorCpuReg(0):= \$0100;                      \ with BIOS interrupt 10h, function 01hCpuReg(2):= \$2000;                      \set cursor type to disappearSoftInt(\$10);loop    [PlayGame;        Key:= ChIn(1);                  \keep playing games until Esc key is hit        if Key = \$1B\Esc\ then                [SetVid(3);  exit];     \clear screen & restore normal text mode        ];]`