# Snake And Ladder

*is a*

**Snake And Ladder****draft**programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Let us create a Snakes and Ladders game where the computer plays against a human player.

For a board example you can use this image here: snakes & ledders.

The way you'll represent the board and the players' tokens is totally up to you: graphics or ASCII graphics or even just text.

Happy coding.

## D[edit]

import std.stdio;

//Board layout, start square to end square

auto snl() {

// Workaround for not being able to static initialize an AA

int[int] temp;

temp[4] = 14;

temp[9] = 31;

temp[17] = 7;

temp[20] = 38;

temp[28] = 84;

temp[40] = 59;

temp[51] = 67;

temp[54] = 34;

temp[62] = 19;

temp[63] = 81;

temp[64] = 60;

temp[71] = 91;

temp[87] = 24;

temp[93] = 73;

temp[95] = 75;

temp[99] = 78;

return temp;

}

int turn(int player, int square) {

import std.random;

auto roll = uniform!"[]"(1, 6);

write("Player ", player, " on square ", square, " rolls a ", roll);

if (square + roll > 100) {

writeln(" but cannot move. Next players turn.");

return square;

} else {

square += roll;

writeln(" and moves to square ", square);

}

auto next = snl().get(square, square);

if (square < next) {

writeln("Yay! Landed on a ladder. Climb up to ", next);

} else if (square > next) {

writeln("Oops! Landed on a snake. Slither down to ", next);

}

return next;

}

void main() {

// three players starting on square one

auto players = [1, 1, 1];

while(true) {

foreach(i,s; players) {

auto ns = turn(i+1, s);

if (ns == 100) {

writeln("Player ", i+1, " wins!");

return;

}

players[i] = ns;

writeln;

}

}

}

- Output:

Player 1 on square 1 rolls a 5 and moves to square 6 Player 2 on square 1 rolls a 6 and moves to square 7 Player 3 on square 1 rolls a 5 and moves to square 6 Player 1 on square 6 rolls a 6 and moves to square 12 Player 2 on square 7 rolls a 4 and moves to square 11 Player 3 on square 6 rolls a 3 and moves to square 9 Yay! Landed on a ladder. Climb up to 31 Player 1 on square 12 rolls a 1 and moves to square 13 Player 2 on square 11 rolls a 1 and moves to square 12 Player 3 on square 31 rolls a 1 and moves to square 32 Player 1 on square 13 rolls a 5 and moves to square 18 Player 2 on square 12 rolls a 5 and moves to square 17 Oops! Landed on a snake. Slither down to 7 Player 3 on square 32 rolls a 5 and moves to square 37 Player 1 on square 18 rolls a 3 and moves to square 21 Player 2 on square 7 rolls a 2 and moves to square 9 Yay! Landed on a ladder. Climb up to 31 Player 3 on square 37 rolls a 3 and moves to square 40 Yay! Landed on a ladder. Climb up to 59 Player 1 on square 21 rolls a 3 and moves to square 24 Player 2 on square 31 rolls a 2 and moves to square 33 Player 3 on square 59 rolls a 5 and moves to square 64 Oops! Landed on a snake. Slither down to 60 Player 1 on square 24 rolls a 3 and moves to square 27 Player 2 on square 33 rolls a 5 and moves to square 38 Player 3 on square 60 rolls a 1 and moves to square 61 Player 1 on square 27 rolls a 6 and moves to square 33 Player 2 on square 38 rolls a 3 and moves to square 41 Player 3 on square 61 rolls a 3 and moves to square 64 Oops! Landed on a snake. Slither down to 60 Player 1 on square 33 rolls a 3 and moves to square 36 Player 2 on square 41 rolls a 1 and moves to square 42 Player 3 on square 60 rolls a 4 and moves to square 64 Oops! Landed on a snake. Slither down to 60 Player 1 on square 36 rolls a 2 and moves to square 38 Player 2 on square 42 rolls a 2 and moves to square 44 Player 3 on square 60 rolls a 4 and moves to square 64 Oops! Landed on a snake. Slither down to 60 Player 1 on square 38 rolls a 5 and moves to square 43 Player 2 on square 44 rolls a 6 and moves to square 50 Player 3 on square 60 rolls a 5 and moves to square 65 Player 1 on square 43 rolls a 2 and moves to square 45 Player 2 on square 50 rolls a 3 and moves to square 53 Player 3 on square 65 rolls a 4 and moves to square 69 Player 1 on square 45 rolls a 1 and moves to square 46 Player 2 on square 53 rolls a 4 and moves to square 57 Player 3 on square 69 rolls a 4 and moves to square 73 Player 1 on square 46 rolls a 3 and moves to square 49 Player 2 on square 57 rolls a 6 and moves to square 63 Yay! Landed on a ladder. Climb up to 81 Player 3 on square 73 rolls a 1 and moves to square 74 Player 1 on square 49 rolls a 2 and moves to square 51 Yay! Landed on a ladder. Climb up to 67 Player 2 on square 81 rolls a 4 and moves to square 85 Player 3 on square 74 rolls a 4 and moves to square 78 Player 1 on square 67 rolls a 3 and moves to square 70 Player 2 on square 85 rolls a 4 and moves to square 89 Player 3 on square 78 rolls a 4 and moves to square 82 Player 1 on square 70 rolls a 3 and moves to square 73 Player 2 on square 89 rolls a 3 and moves to square 92 Player 3 on square 82 rolls a 3 and moves to square 85 Player 1 on square 73 rolls a 3 and moves to square 76 Player 2 on square 92 rolls a 2 and moves to square 94 Player 3 on square 85 rolls a 5 and moves to square 90 Player 1 on square 76 rolls a 4 and moves to square 80 Player 2 on square 94 rolls a 6 and moves to square 100 Player 2 wins!

## Kotlin[edit]

This includes an option for the player to automatically roll again when a six is rolled which I believe is a common variation:

// version 1.2.0

import java.util.Random

val rand = Random()

val snl = mapOf(

4 to 14, 9 to 31, 17 to 7, 20 to 38, 28 to 84, 40 to 59, 51 to 67, 54 to 34,

62 to 19, 63 to 81, 64 to 60, 71 to 91, 87 to 24, 93 to 73, 95 to 75, 99 to 78

)

val sixThrowsAgain = true

fun turn(player: Int, square: Int): Int {

var square2 = square

while (true) {

val roll = 1 + rand.nextInt(6)

print("Player $player, on square $square2, rolls a $roll")

if (square2 + roll > 100) {

println(" but cannot move.")

}

else {

square2 += roll

println(" and moves to square $square2.")

if (square2 == 100) return 100

val next = snl.getOrDefault(square2, square2)

if (square2 < next) {

println("Yay! Landed on a ladder. Climb up to $next.")

if (next == 100) return 100

square2 = next

}

else if (square2 > next) {

println("Oops! Landed on a snake. Slither down to $next.")

square2 = next

}

}

if (roll < 6 || !sixThrowsAgain) return square2

println("Rolled a 6 so roll again.")

}

}

fun main(args: Array<String>) {

// three players starting on square one

val players = intArrayOf(1, 1, 1)

while (true) {

for ((i, s) in players.withIndex()) {

val ns = turn(i + 1, s)

if (ns == 100) {

println("Player ${i+1} wins!")

return

}

players[i] = ns

println()

}

}

}

Sample output:

Player 1, on square 1, rolls a 1 and moves to square 2. Player 2, on square 1, rolls a 3 and moves to square 4. Yay! Landed on a ladder. Climb up to 14. Player 3, on square 1, rolls a 6 and moves to square 7. Rolled a 6 so roll again. Player 3, on square 7, rolls a 3 and moves to square 10. Player 1, on square 2, rolls a 5 and moves to square 7. Player 2, on square 14, rolls a 4 and moves to square 18. Player 3, on square 10, rolls a 5 and moves to square 15. Player 1, on square 7, rolls a 3 and moves to square 10. Player 2, on square 18, rolls a 1 and moves to square 19. Player 3, on square 15, rolls a 1 and moves to square 16. Player 1, on square 10, rolls a 2 and moves to square 12. Player 2, on square 19, rolls a 5 and moves to square 24. Player 3, on square 16, rolls a 2 and moves to square 18. Player 1, on square 12, rolls a 2 and moves to square 14. Player 2, on square 24, rolls a 6 and moves to square 30. Rolled a 6 so roll again. Player 2, on square 30, rolls a 2 and moves to square 32. Player 3, on square 18, rolls a 1 and moves to square 19. Player 1, on square 14, rolls a 6 and moves to square 20. Yay! Landed on a ladder. Climb up to 38. Rolled a 6 so roll again. Player 1, on square 38, rolls a 3 and moves to square 41. Player 2, on square 32, rolls a 4 and moves to square 36. Player 3, on square 19, rolls a 6 and moves to square 25. Rolled a 6 so roll again. Player 3, on square 25, rolls a 3 and moves to square 28. Yay! Landed on a ladder. Climb up to 84. Player 1, on square 41, rolls a 4 and moves to square 45. Player 2, on square 36, rolls a 6 and moves to square 42. Rolled a 6 so roll again. Player 2, on square 42, rolls a 3 and moves to square 45. Player 3, on square 84, rolls a 1 and moves to square 85. Player 1, on square 45, rolls a 1 and moves to square 46. Player 2, on square 45, rolls a 1 and moves to square 46. Player 3, on square 85, rolls a 5 and moves to square 90. Player 1, on square 46, rolls a 1 and moves to square 47. Player 2, on square 46, rolls a 5 and moves to square 51. Yay! Landed on a ladder. Climb up to 67. Player 3, on square 90, rolls a 4 and moves to square 94. Player 1, on square 47, rolls a 4 and moves to square 51. Yay! Landed on a ladder. Climb up to 67. Player 2, on square 67, rolls a 1 and moves to square 68. Player 3, on square 94, rolls a 4 and moves to square 98. Player 1, on square 67, rolls a 5 and moves to square 72. Player 2, on square 68, rolls a 3 and moves to square 71. Yay! Landed on a ladder. Climb up to 91. Player 3, on square 98, rolls a 3 but cannot move. Player 1, on square 72, rolls a 1 and moves to square 73. Player 2, on square 91, rolls a 4 and moves to square 95. Oops! Landed on a snake. Slither down to 75. Player 3, on square 98, rolls a 6 but cannot move. Rolled a 6 so roll again. Player 3, on square 98, rolls a 6 but cannot move. Rolled a 6 so roll again. Player 3, on square 98, rolls a 2 and moves to square 100. Player 3 wins!

## Perl 6[edit]

Snakes and ladders is entirely chance based, so human interaction is not really required. This version allows up to one human player against any number of computer players and asks for input... but doesn't really *need* or even *use* it. I didn't bother to implement a graphical interface.

# board layout

my %snl = 4, 14, 9, 31, 17, 7, 20, 38, 28, 84, 40, 59, 51, 67, 54, 34,

62, 19, 63, 81, 64, 60, 71, 91, 87, 24, 93, 73, 95, 75, 99, 78;

my @players = 1, 1, 1; # three players, starting on square 1

my $human = 1; # player 1 is human. set to 0 for all computer players

loop {

for ^@players -> $player {

turn(@players[$player], $player + 1);

}

say '';

}

sub turn ($square is rw, $player) {

if $player == $human {

prompt "You are on square $square. Hit enter to roll the die.";

}

my $roll = (1..6).roll;

my $turn = $square + $roll;

printf "Player $player on square %2d rolls a $roll", $square;

if $turn > 100 {

say " but cannot move. Next players turn.";

return $square;

}

if %snl{$turn} {

$square = %snl{$turn};

if $turn > $square {

say ". Oops! Landed on a snake. Slither down to $square."

} else {

say ". Yay! Landed on a ladder. Climb up to $square."

}

} else {

$square = $turn;

say " and moves to square $square";

}

say "Player $player wins!" and exit if $square == 100;

return $square;

}

- Sample output:

You are on square 1. Hit enter to roll the die. Player 1 on square 1 rolls a 1 and moves to square 2 Player 2 on square 1 rolls a 4 and moves to square 5 Player 3 on square 1 rolls a 1 and moves to square 2 You are on square 2. Hit enter to roll the die. Player 1 on square 2 rolls a 1 and moves to square 3 Player 2 on square 5 rolls a 2 and moves to square 7 Player 3 on square 2 rolls a 3 and moves to square 5 You are on square 3. Hit enter to roll the die. Player 1 on square 3 rolls a 4 and moves to square 7 Player 2 on square 7 rolls a 1 and moves to square 8 Player 3 on square 5 rolls a 2 and moves to square 7 You are on square 7. Hit enter to roll the die. Player 1 on square 7 rolls a 2. Yay! Landed on a ladder. Climb up to 31. Player 2 on square 8 rolls a 3 and moves to square 11 Player 3 on square 7 rolls a 2. Yay! Landed on a ladder. Climb up to 31. ... about 15 turns omitted ... You are on square 90. Hit enter to roll the die. Player 1 on square 90 rolls a 3. Oops! Landed on a snake. Slither down to 73. Player 2 on square 55 rolls a 3 and moves to square 58 Player 3 on square 90 rolls a 4 and moves to square 94 You are on square 73. Hit enter to roll the die. Player 1 on square 73 rolls a 6 and moves to square 79 Player 2 on square 58 rolls a 5. Yay! Landed on a ladder. Climb up to 81. Player 3 on square 94 rolls a 3 and moves to square 97 You are on square 79. Hit enter to roll the die. Player 1 on square 79 rolls a 3 and moves to square 82 Player 2 on square 81 rolls a 6. Oops! Landed on a snake. Slither down to 24. Player 3 on square 97 rolls a 5 but cannot move. Next players turn. You are on square 82. Hit enter to roll the die. Player 1 on square 82 rolls a 5. Oops! Landed on a snake. Slither down to 24. Player 2 on square 24 rolls a 6 and moves to square 30 Player 3 on square 97 rolls a 4 but cannot move. Next players turn. You are on square 24. Hit enter to roll the die. Player 1 on square 24 rolls a 4. Yay! Landed on a ladder. Climb up to 84. Player 2 on square 30 rolls a 5 and moves to square 35 Player 3 on square 97 rolls a 4 but cannot move. Next players turn. You are on square 84. Hit enter to roll the die. Player 1 on square 84 rolls a 1 and moves to square 85 Player 2 on square 35 rolls a 2 and moves to square 37 Player 3 on square 97 rolls a 3 and moves to square 100 Player 3 wins!

## Racket[edit]

#lang racket/base

(define portals (hash 4 14 9 31 17 7 20 38 28 84 40 59 51 67 54 34 62 19 63 81 64 60 71 91 87 24 93 73 95 75 99 78))

(define (find-game-winner n-players reroll-on-six? (win values))

(let turn ((positions-map (for/hash ((p n-players)) (values p 1))) (player 0))

(newline)

(let ((die (add1 (random 6)))

(position (hash-ref positions-map player)))

(printf "player ~a at ~a rolls ~a: " (add1 player) position die)

(let* ((try-position (+ position die))

(new-position

(cond [(> try-position 100) (display "player can't move beyond the end.") position]

[(= try-position 100) (display "player wins!") try-position]

[(hash-ref portals try-position #f)

=> (λ (slide-to)

(printf "~a from ~a to ~a." (if (> slide-to try-position) "LADDER" "SNAKE") try-position slide-to)

slide-to)]

[else (printf "landed on ~a." try-position) try-position])))

(if (= new-position 100)

(win (add1 player))

(turn (hash-set positions-map player new-position)

(if (and (= 6 die) reroll-on-six?)

(begin0 player (display " [6] rolls again!"))

(modulo (add1 player) n-players))))))))

(module+ main

(find-game-winner 5 #t (λ (p) (printf "~%~%The winner of the game is player #~a" p))))

- Output:

player 1 at 1 rolls 2: landed on 3. player 2 at 1 rolls 3: LADDER from 4 to 14. player 3 at 1 rolls 6: landed on 7. [6] rolls again! player 3 at 7 rolls 4: landed on 11. player 4 at 1 rolls 3: LADDER from 4 to 14. player 5 at 1 rolls 5: landed on 6. player 1 at 3 rolls 1: LADDER from 4 to 14. player 2 at 14 rolls 3: SNAKE from 17 to 7. player 3 at 11 rolls 4: landed on 15. ... player 3 at 86 rolls 5: landed on 91. player 4 at 85 rolls 1: landed on 86. player 5 at 68 rolls 6: landed on 74. [6] rolls again! player 5 at 74 rolls 1: landed on 75. player 1 at 59 rolls 1: landed on 60. player 2 at 94 rolls 6: player wins! The winner of the game is player #2

## Ruby[edit]

NONE = 0; LADDER = 1; SNAKE = 2; STAY = 1; MOVE = 2; WIN = 3

class Cell

@type; @to; attr_reader :type, :to

def initialize; @type = NONE; @to = 0; end

def set( t, o ); @type = t; @to = o; end

end

class Player

@pos; @name; attr_accessor :pos; attr_reader :name

def initialize( n ); @pos = 0; @name = n; end

def play( dice )

s = dice.roll; return s, STAY if @pos + s > 99

@pos += s; return s, WIN if @pos == 99

return s, MOVE

end

end

class Die

@sides; def initialize( s = 6 ); @sides = s; end

def roll; return 1 + rand( @sides ); end

end

def initBoard

@board = Array.new( 100 ); for i in 0 .. 99; @board[i] = Cell.new(); end

@board[3].set( LADDER, 13 ); @board[8].set( LADDER, 30 ); @board[19].set( LADDER, 37 );

@board[27].set( LADDER, 83 );@board[39].set( LADDER, 58 ); @board[50].set( LADDER, 66 );

@board[62].set( LADDER, 80 ); @board[70].set( LADDER, 90 ); @board[16].set( SNAKE, 6 );

@board[61].set( SNAKE, 18 ); @board[86].set( SNAKE, 23 ); @board[53].set( SNAKE, 33 );

@board[63].set( SNAKE, 59 ); @board[92].set( SNAKE, 72 ); @board[94].set( SNAKE, 74 );

@board[98].set( SNAKE, 77 );

end

def initPlayers

@players = Array.new( 4 );

for i in 0 .. @playersCount - 1; @players[i] = Player.new( "player " << i + 49 ); end

end

def play

initBoard; initPlayers; @die = Die.new

while true

for p in 0 .. @playersCount - 1

puts; puts

if( 0 == p )

print "#{@players[p].name}, your turn. Your position is cell #{@players[p].pos + 1}.\n"<<

"Press [RETURN] to roll the die."

gets; np = @players[p].play( @die ); print "You rolled a #{np[0]}\n"

if np[1] == WIN

print "You reached position #{@players[p].pos + 1} and win the game!!!!\n"; return

elsif np[1] == STAY; print "Sorry, you cannot move!\n"

else print "Your new position is cell #{@players[p].pos + 1}.\n";

end

else

np = @players[p].play( @die ); print "#{@players[p].name} rolled a #{np[0]}.\n"

if np[1] == WIN

print "He reached position #{@players[p].pos + 1} and wins the game!!!!\n"; return

elsif np[1] == STAY; print "But he cannot move....\n"

else print "His new position is cell #{@players[p].pos + 1}.\n";

end

end

s = @board[@players[p].pos].type

next if s == NONE

@players[p].pos = @board[@players[p].pos].to

case s

when SNAKE; print "What a pitty, landed on a snake. "

when LADDER; print "Lucky move! Landed on a ladder. "

end

print "New position is cell #{@players[p].pos + 1}.\n"

end

end

end

@playersCount = 4; @board; @players; @die

play

- Output:

... player 1, your turn. Your position is cell 97. Press [RETURN] to roll the die. You rolled a 5 Sorry, you cannot move!

player 2 rolled a 5. His new position is cell 49.

player 3 rolled a 4. But he cannot move....

player 4 rolled a 6. His new position is cell 91.

player 1, your turn. Your position is cell 97. Press [RETURN] to roll the die. You rolled a 3 You reached position 100 and win the game!!!!