# Flipping bits game

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Flipping bits game
You are encouraged to solve this task according to the task description, using any language you may know.
The game

Given an   N×N   square array of zeroes or ones in an initial configuration,   and a target configuration of zeroes and ones.

The game is to transform one to the other in as few moves as possible by inverting whole numbered rows or whole lettered columns at once   (as one move).

In an inversion.   any  1  becomes  0,   and any  0  becomes  1  for that whole row or column.

Task

Create a program to score for the Flipping bits game.

1. The game should create an original random target configuration and a starting configuration.
2. Ensure that the starting position is never the target position.
3. The target position must be guaranteed as reachable from the starting position.   (One possible way to do this is to generate the start position by legal flips from a random target position.   The flips will always be reversible back to the target from the given start position).
4. The number of moves taken so far should be shown.

Show an example of a short game here, on this page, for a   3×3   array of bits.

## 11l

Translation of: Python
```V ascii_lowercase = ‘abcdefghij’
V digits = ‘0123456789’ // to get round ‘bug in MSVC 2017’[https://developercommunity.visualstudio.com/t/bug-with-operator-in-c/565417]

V n = 3

V board = [[0] * n] * n

F setbits(&board, count = 1)
L 0 .< count
board[random:(:n)][random:(:n)] (+)= 1

F fliprow(i)
L(j) 0 .< :n
:board[i - 1][j] (+)= 1

F flipcol(i)
L(&row) :board
row[i] (+)= 1

F shuffle(board, count = 1)
L 0 .< count
I random:(0 .< 2) != 0
fliprow(random:(:n) + 1)
E
flipcol(random:(:n))

F pr(board, comment = ‘’)
print(comment)
print(‘     ’(0 .< :n).map(i -> :ascii_lowercase[i]).join(‘ ’))
print(‘  ’enumerate(board, 1).map((j, line) -> ([‘#2’.format(j)] [+] line.map(i -> String(i))).join(‘ ’)).join("\n  "))

F init(&board)
setbits(&board, count' random:(:n) + 1)
V target = copy(board)
L board == target
shuffle(board, count' 2 * :n)
V prompt = ‘  X, T, or 1-#. / #.-#. to flip: ’.format(:n, :ascii_lowercase[0], :ascii_lowercase[:n - 1])
R (target, prompt)

V (target, prompt) = init(&board)
pr(target, ‘Target configuration is:’)
print(‘’)
V turns = 0
L board != target
turns++
pr(board, turns‘:’)
V ans = input(prompt).trim(‘ ’)
I (ans.len == 1 & ans C ascii_lowercase & ascii_lowercase.index(ans) < n)
flipcol(ascii_lowercase.index(ans))
E I ans != ‘’ & all(ans.map(ch -> ch C :digits)) & Int(ans) C 1 .. n
fliprow(Int(ans))
E I ans == ‘T’
pr(target, ‘Target configuration is:’)
turns--
E I ans == ‘X’
L.break
E
print("  I don't understand '#.'... Try again. (X to exit or T to show target)\n".format(ans[0.<9]))
turns--
L.was_no_break
print("\nWell done!\nBye.")```
Output:
```Target configuration is:
a b c
1 0 0 1
2 0 0 0
3 0 0 0

1:
a b c
1 1 1 0
2 0 0 0
3 1 1 1
X, T, or 1-3 / a-c to flip: 1
2:
a b c
1 0 0 1
2 0 0 0
3 1 1 1
X, T, or 1-3 / a-c to flip: 3

Well done!
Bye.
```

## 8080 Assembly

This program runs under CP/M and takes the board size from the command line.

```		;;; Flip the Bits game, CP/M version.
;;; CP/M zero page locations
cmdln:		equ	80h
;;; CP/M system calls
getch: 		equ	1h
putch:		equ	2h
rawio:		equ	6h
puts:		equ	9h
org	100h
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Retrieve command line input. If it is not correct, end.
lxi	d,usage	; Usage string
mvi	c,puts	; Print that string when we need to
lxi	h,cmdln	; Pointer to command line
mov	a,m	; Get length
ana	a	; Zero?
jc	5	; Then print and stop
inx	h	; Advance to first non-space element
inx	h
mov	a,m	; Get first character
sui	'3'	; Minimum number
jc	5	; If input was less than that, print and stop
adi	3	; Add 3 back, giving the board size
cpi	9	; Is it higher than 8 now?
jnc	5	; Then print usage and stop
sta	boardsz	; Store the board size
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Because there's no standard way in CP/M to get at any
;;; entropy (not even a clock), ask the user to supply some
;;; by pressing the keys on the keyboard.
lxi	d,presskeys
call	outs
mvi	b,8	; we want to do this 8 times, for 24 keys total
randouter:	mvi	c,3	; there are 3 bytes of state for the RNG
lxi	h,xabcdat+1
randinner:	push	h	; keep the pointer and counters
push	b
waitkey:	mvi	c,rawio
mvi	e,0FFh
call	5
ana	a
jz	waitkey
pop	b	; restore the pointer and counters
pop	h
xra	m	; XOR key with data
mov	m,a
inx	h
dcr 	c	; Have we had 3 bytes yet?
jnz	randinner
dcr	b	; Have we done it 8 times yet?
jnz	randouter
lxi	d,welcome
call	outs
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Generate a random board
lxi	h,board
lxi	b,4001h	; B=81, C=1
genrand:	call	xabcrand
ana	c
mov	m,a
inx	h
dcr	b
jnz	genrand
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Copy board into goal
lxi	h,board
lxi	d,goal
mvi	b,64
copygoal:	mov	a,m
stax	d
inx	h
inx	d
dcr	b
jnz	copygoal
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Do a bunch of random flips on the board (5-20)
call	xabcrand
ani	0Fh	; 0..15 flips
adi	5	; 5..20 flips
sta	sysflips
mov	b,a	; Do that many flips
randflip:	call	xabcrand
call 	flip 	; Unused bits in the random number are ignored
dcr	b
jnz	randflip
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print the current state
gamestate:	lxi	d,smoves
call	outs
lda 	usrflips
call	outanum
lxi 	d,sgoal
call	outs
lda	sysflips
call 	outanum
lxi	d,newline
call	outs
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print the current board and the goal
;;; Print the header first
lxi	d,sboardhdr
call	outs
lda	boardsz
lxi	d,2041h	; E=letter (A), D=space
add	e	; Last letter
mov 	b,a 	; B = last letter
mvi	l,2	; Print two headers
header:		mvi	e,'A'
mov	a,d
call	outaspace
headerpart:	mov	a,e
cmp	b
jc	headerltr
mov	a,d	; Print spaces for invalid positions
headerltr:	call	outaspace
mov	a,e
inr	a
mov	e,a
cpi	'A'+8
jc	headerpart
mvi	a,9
call	outa
dcr	l	; Print two headers (for two boards)
jnz	header
lxi	d,newline
call	outs
;;;	Then print each line of the board
mvi 	c,0	; Start with line 0
printline:	lxi	h,board	; Get position on board
mvi	d,2	; Run twice - print board and goal
prbrdline:	mvi	a,'1'	; Print line number
add	c
call	outaspace
push	d
mov	a,c	; Line offset in board
rlc
rlc
rlc
mov	e,a
mvi	d,0
dad	d	; Add line offset
pop	d	; Restore board counter
mvi	b,0	; Start with column 0
printcol:	lda	boardsz	; Valid position?
dcr	a
cmp	b
jnc	printbit
mvi	a,' '	; No - print space
jmp	printpos
printbit:	mov	a,m	; Yes - print 0 or 1
adi	'0'
printpos:	call	outaspace
inx	h	; Next board pos
inr 	b
mov	a,b	; Done yet?
cpi	8
jnz	printcol	; If not, print next column
mvi	a,9
call	outa
lxi 	h,goal	; Print goal line next
dcr	d
jnz 	prbrdline
mvi	a,13	; Print newline
call	outa
mvi	a,10
call	outa
inr	c	; Next line
lda	boardsz	; Valid line?
dcr	a
cmp	c
jnc	printline
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Prompt the user for a move
lxi	d,prompt	; Print prompt
call	outs
readinput:	mvi	c,getch		; Read character
call	5
ori	32 		; Make letters lowercase
cpi	'q' 		; Quit?
rz
cpi	'9'+1		; 9 or lower? assume number
jc	nummove
sui	'a'		; Otherwise, assume letter
jc	invalid		; So <'a' is invalid input
call	checkmove	; See if the move is valid
jc	invalid		; If not, wrong input
ori	128		; Set high bit for column flip
call	flip		; Do the flip
jmp	checkboard	; See if the game is won
nummove:	sui	'1'		; Board array is 0-based of course
jc	invalid		; Not on board = invalid input
call	checkmove	; See if the move is vali
jc	invalid
call	flip 		; Do the move (high bit clear for row)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; See if the user has won
checkboard:	lda	boardsz
dcr	a
mov	b,a		; B = line
checkrow:	lda	boardsz
dcr	a
mov	c,a		; C = column
checkcol:	mov	a,b
rlc			; Line * 8
rlc
rlc
add	c		; + column = offset
push	b		; Store line/column
mvi	h,0		; Position offset
mov	l,a
lxi	d,board		; Get board
dad	d
mov	b,m		; B = board position
lxi	d,64		; Goal = board+64
dad	d
mov	a,m		; A = goal position
cmp	b		; Are they the same?
pop 	b		; Restore line/column
jnz	nowin		; If not, the user hasn't won
dcr	c		; If so, try next column position
jp	checkcol
dcr	b		; If column done, try next row
jp	checkrow
;;;	If we get here, the user has won
lxi	d,win
jmp	outs
;;;	The user hasn't won yet, get another move
nowin:		lxi	h,usrflips	; Increment the user flips
inr	m
jmp	gamestate	; Print new game state, get new move
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Invalid input: erase it, beep, and get another character
invalid:	lxi	d,nope
call	outs
jmp	readinput
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Check if the move in A is valid. Set carry if not.
checkmove:	mov	b,a
lda	boardsz
dcr	a
cmp	b
mov	a,b
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Flip row or column A & 7 (zero-indexed) on the board.
;;; Bit 7 set = column, else row.
flip:		rlc		; Test bit 7 (and A*2)
jc	flipcol
;;; Flip row
push	b	; Keep registers
push	h
ani	0Eh	; Get row number
rlc		; Calculate offset, A*4
rlc		; A*8
mvi	b,0	; BC = A
mov	c,a
lxi	h,board	; Get board pointer
dad	b	; Add row offset
lxi	b,0801h	; Max. 8 bits, and C=1 (to flip)
fliprowbit:	mov	a,m	; Get position
xra	c	; Flip position
mov	m,a	; Store position
inx	h	; Increment pointer
dcr	b	; Done yet?
jnz	fliprowbit
pop	h	; Restore registers
pop	b
ret
;;; Flip column
flipcol:	push	b	; Keep registers
push	d
push	h
rrc		; Rotate A back
ani 	7	; Get column number
mvi	d,0	; Column offset
mov	e,a
lxi	h,board	; Get board pointer
dad	d	; Add column offset
mvi	e,8	; Advance by 8 each time through the loop
lxi	b,0801h	; Max. 8 bits, and C=1 (to flip)
flipcolbit:	mov	a,m	; Get position
xra	c	; Flip position
mov	m,a	; Store position
dad	d	; Next row
dcr	b	; Done yet?
jnz	flipcolbit
pop	h	; Restore registers
pop	d
pop 	b
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; The "X ABC" 8-bit random number generator
xabcrand:       push	h
lxi     h,xabcdat
inr     m       ; X++
mov     a,m     ; X,
inx     h       ;
xra     m       ; ^ C,
inx     h       ;
xra     m       ; ^ A,
mov     m,a     ; -> A
inx     h
add     m       ; + B,
mov     m,a     ; -> B
rar             ; >>1
dcx     h
xra     m       ; ^ A,
dcx     h
add     m       ; + C
mov     m,a     ; -> C
pop	h
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print the string in DE. This saves one byte per call.
outs:		mvi	c,puts
jmp	5
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print the number in A in decimal, preserving registers
outanum:	push	psw
push	b
push	d
push	h
lxi 	d,outabuf+3
outadgt:	mvi 	b,-1
outdivmod:	inr	b
sui	10
jnc	outdivmod
adi	10+'0'
dcx	d
stax	d
mov	a,b
ana	a
jnz	outadgt
call 	outs
jmp	regrestore
outabuf:	db	'***\$'	; Room for ASCII number
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print the character in A followed by a space, preserving
;;; registers.
outaspace:	call	outa
push	psw
mvi	a,' '
call	outa
pop	psw
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print the character in A, preserving all registers.
outa:		push	psw
push	b
push 	d
push	h
mov	e,a
mvi	c,putch
call	5
regrestore:	pop	h
pop	d
pop	b
pop	psw
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Strings
usage:		db	'Usage: FLIP [3..8], number is board size.\$'
presskeys:	db	'Please press some keys to generate a random state...\$'
welcome:	db	'done.',13,10,13,10
db	'*** FLIP THE BITS *** ',13,10
db	'--------------------- ',
newline:	db	13,10,'\$'
smoves:		db	13,10,13,10,'Your flips: \$'
sgoal:		db	9,'Goal: \$'
sboardhdr:	db	'--Board------------',9,'--Goal-------------',13,10,'\$'
prompt:		db	'Press line or column to flip, or Q to quit: \$'
nope:		db	8,32,8,7,'\$'	; Beep and erase input
win:		db	13,10,7,7,7,'You win!\$'
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Data
boardsz:	ds	1		; This will hold the board size
sysflips:	ds	1		; How many flips the system did
usrflips:	ds	1		; How many flips the user did
xabcdat:	ds	4		; RNG state
board:		equ	\$
goal:		equ	board + 64	; Max. 8*8 board```
Output:

Example game:

```A>flip 3
Please press some keys to generate a random state...done.

*** FLIP THE BITS ***
---------------------

Your flips: 0   Goal: 20
--Board------------     --Goal-------------
A B C                   A B C
1 0 0 0                 1 0 1 1
2 0 0 0                 2 1 0 0
3 1 1 1                 3 0 1 1
Press line or column to flip, or Q to quit: a

Your flips: 1   Goal: 20
--Board------------     --Goal-------------
A B C                   A B C
1 1 0 0                 1 0 1 1
2 1 0 0                 2 1 0 0
3 0 1 1                 3 0 1 1
Press line or column to flip, or Q to quit: 1
You win!
A>```

## 8086 Assembly

This program runs under MS-DOS and takes the board size from the command line.

```		bits	16
cpu	8086
;;; MS-DOS PSP locations
arglen:		equ	80h
argstart:	equ	82h
;;; MS-DOS system calls
getch:		equ	1h
putch:		equ	2h
puts:		equ	9h
time:		equ	2Ch
section		.text
org	100h
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Read board size from command line
cmp	byte [arglen],0	; Command line empty?
je	printusage	; Then print usage and stop
mov	al,[argstart]	; Get first byte on command line
cmp	al,'3'		; <3?
jb	printusage	; Then print usage and stop
cmp	al,'8'		; >8?
ja	printusage	; Then print usage and stop
sub	al,'0'		; Make number from ASCII
mov	[boardsz],al	; Store the board size
mov	ah,puts		; If we made it here, print the
mov	dx,welcome	; welcome banner.
int	21h
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Generate random board
call	xabcinit	; Initialize the RNG with system time
mov	si,board
xor	bx,bx
genboard:	call 	xabcrand	; Get random byte
mov	ah,al
call	xabcrand	; Get another
and	ax,0101h	; Keep only the low bit of each byte
mov	[si+bx],ax	; And store them
inc	bx		; Two bytes onward
inc	bx
cmp 	bl,64		; Are we done?
jne	genboard
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Copy the board into the goal
mov	si,board	; Source is board
mov	di,goal		; Destination is goal
mov	bx,0		; Start at the beginning
copyboard:	mov	ax,[si+bx]	; Load word from board
mov	[di+bx],ax	; Store word in goal
inc	bx		; We've copied two bytes
inc	bx
cmp 	bl,64		; Are we done yet?
jne 	copyboard
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Make an amount of random flips
call	xabcrand	; Random number
and	al,15		; [0..15]
add	al,5		; [5..20]
mov	[sysflips],al	; Store in memory
mov	cl,al		; Flip doesn't touch CL
xor	ch,ch		; Set high byte zero
randflips:	call	xabcrand	; Random number
call 	flip		; Do a flip (unused bits are ignored)
loop 	randflips
mov	byte [usrflips],0	; Initialize user flips to 0
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print game status (moves, goal moves)
status:		mov	ah,puts
mov	dx,smoves
int	21h
mov	al,[usrflips]
call	printal
mov	ah,puts
mov	dx,sgoal
int	21h
mov	al,[sysflips]
call	printal
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print the game board and goal board
mov	ah,puts		; Print the header
mov	dx,sboardhdr
int	21h
mov	cl,2		; Print two headers
mov	ah,putch	; Indent columns
;;; Print column headers
colheader:	mov	dl,' '
int	21h
int	21h
mov	bh,0		; Offset
mov	bl,'A'		; First letter
.curcol:	cmp 	bh,[boardsz]
mov	dl,bl		; Print letter
jb	.printcol
mov	dl,' '		; Print space if column not used
.printcol:	call	dlspace		; Print DL + separator space
inc	bl
inc	bh
cmp 	bh,8		; Done yet?
jb	.curcol
mov	dl,9		; Separate the boards with a TAB
int	21h
dec	cl		; We need two headers (board and goal)
jnz	colheader
mov	ah,puts		; Print a newline afterwards
mov	dx,newline
int	21h
;;; Print the rows of the boards
xor	bh,bh		; Zero high byte of BX
xor	cl,cl		; Row index
boardrow:	mov	ch,2		; Two rows, board and goal
mov	si,board	; Start by printing the game board
.oneboard:	xor	dh,dh		; Column index
mov	dl,cl		; Print row number
add	dl,'1'
call	dlspace
.curpos:	cmp	dh,[boardsz]	; Column in use?
mov	dl,' '		; If not, print a space
jae	.printpos
mov	bl,cl		; Row index
shl	bl,1		; * 8
shl 	bl,1
shl 	bl,1
add	bl,dh		; Add column index
mov	dl,[bx+si]	; Get position from board
add	dl,'0'		; Print as ASCII 0 or 1
.printpos:	call	dlspace
inc	dh		; Increment column index
cmp	dh,8		; Are we there yet?
jb	.curpos		; If not, print next position
mov	dl,9		; Separate the boards with a TAB
int	21h
dec	ch		; Have we printed the goal yet?
mov	si,goal		; If not, print the goal next
jnz	.oneboard
mov	ah,puts		; Print a newline
mov	dx,newline
int	21h
inc	cl		; Next row
cmp	cl,[boardsz]	; Are we there yet?
jb	boardrow	; If not, print the next row.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Ask the user for a move
mov	ah,puts		; Write the prompt
mov	dx,prompt
int	21h
readmove:	mov	ah,getch 	; Read a character
int	21h
or	al,32		; Make letters lowercase
cmp 	al,'q'		; Quit?
je	quit
cmp	al,'9'		; Numeric (row) input?
jbe	.nummove	; If not, alphabetic (column) input
;;; Letter input (column)
sub	al,'a'		; Subtract 'a'
jc	invalid		; If it was <'a', invalid input
cmp 	al,[boardsz]	; Is it on the board?
jae	invalid
or	al,128		; Set high bit, for column flip
call	flip		; Flip the column
jmp	checkwin	; See if the user has won
;;; Number input (row)
.nummove:	sub	al,'1'		; Rows start at 1.
jc	invalid		; If <'1', then invalid
cmp	al,[boardsz]	; Is it on the board?
jae	invalid
call	flip		; Flip the row
;;; Check if the user has won the game
checkwin:	xor	bh,bh		; Zero high byte of array index
mov	dl,[boardsz]
xor	ch,ch		; Row coordinate
.row:		xor	cl,cl		; Column coordinate
.pos:		mov	bl,ch		; BL = row*8 + col
shl	bl,1
shl	bl,1
shl 	bl,1
add	bl,cl
mov 	al,[board+bx]	; Get position from board
cmp	al,[goal+bx]	; Compare with corresponding goal pos
jne	.nowin		; Not equal: the user hasn't won
inc	cl
cmp	cl,dl		; Done all positions on row?
jb	.pos		; If not, do next.
inc	ch
cmp	ch,dl 		; Done all rows?
jb	.row		; If not, do next.
;;; If we get here, the user has won
mov	ah,puts
mov	dx,win
int	21h
ret
;;; The user hasn't won
.nowin:		inc	byte [usrflips]	; Record that the user has made a move
jmp	status		; Print status and board, get new move
;;; Invalid input
invalid:	mov	ah,puts
mov	dx,nope
int	21h
jmp	readmove
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Flip the line or column in AL. If bit 7 set, flip column.
flip:		mov	si,board	; SI = board
test	al,al		; This sets sign flag if bit 7 set
js	.column		; If so, flip column.
and	al,7		; We only need the first 3 bits
shl	al,1		; Multiply by 8
shl	al,1		; 8086 does not support 'shl al,3'
shl 	al,1
xor	ah,ah 		; High byte 0
mov	bx,ax		; BX = offset
mov	ah,4		; 4 words
.rowloop	xor	word [si+bx],0101h	; Flip two bytes at once
inc	bx
inc	bx
dec	ah
jnz	.rowloop
ret
.column:	and	al,7		; Flip a column.
xor	ah,ah
mov	bx,ax		; BX = row offset
mov	ah,8		; 8 bytes (need to do it byte by byte)
.colloop:	xor	byte [si+bx],01h	; Flip position
add	bx,8
dec	ah
jnz	.colloop
quit:		ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print usage and stop
printusage:	mov	ah,puts
mov	dx,usage
int	21h
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print the character in DL followed by a space
dlspace:	mov	ah,putch
int	21h
mov	dl,' '
int	21h
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Initialize the random number generator using the system
;;; time.
xabcinit:	mov	ah,time
int	21h
mov	bx,xabcdat
xor	[bx],cx
xor	[bx+2],dx
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; The "X ABC" random number generator
;;; Return random byte in AL
xabcrand:	push	bx		; Save registers
push	cx
push	dx
mov	bx,xabcdat	; RNG state pointer
mov	cx,[bx]		; CL=x CH=a
mov	dx,[bx+2]	; DL=b DH=c
inc 	cl		; X++
xor	ch,dh		; A^=C
xor	ch,cl		; A^=X
add	dl,ch		; B+=A
mov	al,dl
shr	al,1		; B>>1
xor	al,ch		; ^A
add	al,dh		; +C
mov	dh,al		; ->C
mov	[bx],cx		; Store new RNG state
mov	[bx+2],dx
pop	dx		; Restore registers
pop 	cx
pop 	bx
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Print the byte in AL as a decimal number
printal:	mov	di,decnum + 3	; Room in memory for decimal number
mov	dl,10		; Divide by 10
.loop:		xor	ah,ah		; Zero remainder
div	dl		; Divide by 10
add	ah,'0'		; Add ASCII 0 to remainder
dec	di
mov	[di],ah		; Store digit in memory
and	al,al		; Done yet?
jnz	.loop		; If not, next digit
mov	dx,di		; DX = number string
mov	ah,puts		; Print the string
int	21h
ret
section		.data
decnum:		db	'***\$'	; Decimal number placeholder
usage:		db	'Usage: FLIP [3..8], number is board size.\$'
welcome:	db	'*** FLIP THE BITS *** ',13,10
db	'--------------------- ',
newline:	db	13,10,'\$'
smoves:		db	13,10,13,10,'Your flips: \$'
sgoal:		db	9,'Goal: \$'
sboardhdr:	db	13,10,10,'--Board------------'
db	9,'--Goal-------------',13,10,'\$'
prompt:		db	13,10,'Press line or column to flip, or Q to quit: \$'
nope:		db	8,32,8,7,'\$'	; Beep and erase input
win:		db	13,10,7,7,7,'You win!\$'
section		.bss
boardsz:	resb 	1	; Board size
sysflips:	resb	1	; Amount of flips that the system does
usrflips:	resb	1	; Amount of flips that the user does
xabcdat:	resb	4	; Four byte RNG state
board:		resb	64	; 8*8 board
goal:		resb	64	; 8*8 goal
```
Output:

Example game:

```C:\>flip86 3
*** FLIP THE BITS ***
---------------------

Your flips: 0	Goal: 6

--Board------------	--Goal-------------
A B C           	  A B C
1 1 1 0           	1 1 1 1
2 1 0 0           	2 0 1 0
3 1 1 1           	3 1 1 0

Press line or column to flip, or Q to quit: 2

Your flips: 1	Goal: 6

--Board------------	--Goal-------------
A B C           	  A B C
1 1 1 0           	1 1 1 1
2 0 1 1           	2 0 1 0
3 1 1 1           	3 1 1 0

Press line or column to flip, or Q to quit: c
You win!
C:\>```

## Action!

```BYTE boardX=[13],boardY=[10],goalX=[22]

PROC UpdateBoard(BYTE ARRAY board BYTE side,x0,y0)
BYTE x,y

FOR y=0 TO side-1
DO
Position(x0,y0+2+y)
Put(y+'1)
FOR x=0 TO side-1
DO
IF y=0 THEN
Position(x0+2+x,y0)
Put(x+'A)
FI
Position(x0+2+x,y0+2+y)
PrintB(board(x+y*side))
OD
OD
RETURN

PROC Randomize(BYTE ARRAY board BYTE len)
BYTE i

FOR i=0 TO len-1
DO
board(i)=Rand(2)
OD
RETURN

BYTE FUNC Solved(BYTE ARRAY goal,board BYTE side)
BYTE i,len

len=side*side
FOR i=0 TO len-1
DO
IF goal(i)#board(i) THEN
RETURN (0)
FI
OD
RETURN (1)

PROC FlipRow(BYTE ARRAY board BYTE side,row)
BYTE i,ind

IF row>=side THEN RETURN FI
FOR i=0 TO side-1
DO
ind=i+row*side
board(ind)=1-board(ind)
OD
UpdateBoard(board,side,boardX,boardY)
RETURN

PROC FlipColumn(BYTE ARRAY board BYTE side,column)
BYTE i,ind

IF column>=side THEN RETURN FI
FOR i=0 TO side-1
DO
ind=column+i*side
board(ind)=1-board(ind)
OD
UpdateBoard(board,side,boardX,boardY)
RETURN

PROC Wait(BYTE frames)
BYTE RTCLOK=\$14
frames==+RTCLOK
WHILE frames#RTCLOK DO OD
RETURN

PROC UpdateStatus(BYTE ARRAY goal,board BYTE side)
Position(9,3) Print("Game status: ")
IF Solved(goal,board,side) THEN
Print("SOLVED !")
Sound(0,100,10,5) Wait(5)
Sound(0,60,10,5) Wait(5)
Sound(0,40,10,5) Wait(5)
Sound(0,0,0,0)
ELSE
Print("Shuffled")
FI
RETURN

PROC Init(BYTE ARRAY goal,board BYTE side)
BYTE size,i,n

size=side*side
Randomize(goal,size)
MoveBlock(board,goal,size)
UpdateBoard(goal,side,goalX,boardY)

WHILE Solved(goal,board,side)
DO
FOR i=1 TO 20
DO
n=Rand(side)
IF Rand(2)=0 THEN
FlipRow(board,side,n)
ELSE
FlipColumn(board,side,n)
FI
OD
OD
RETURN

PROC Main()
DEFINE SIDE="3"
DEFINE SIZE="9"
BYTE ARRAY board(SIZE),goal(SIZE)
BYTE CRSINH=\$02F0 ;Controls visibility of cursor
BYTE k,CH=\$02FC ;Internal hardware value for last key pressed

Graphics(0)
SetColor(2,0,2)
CRSINH=1 ;hide cursor
Position(boardX,boardY-2) Print("Board")
Position(goalX+1,boardY-2) Print("Goal")
Position(9,19) Print("Space bar - shuffle")
Init(goal,board,SIDE)
UpdateStatus(goal,board,side)

DO
k=CH
IF k#\$FF THEN
CH=\$FF
IF k=31 THEN FlipRow(board,SIDE,0)
ELSEIF k=30 THEN FlipRow(board,SIDE,1)
ELSEIF k=26 THEN FlipRow(board,SIDE,2)
ELSEIF k=63 THEN FlipColumn(board,SIDE,0)
ELSEIF k=21 THEN FlipColumn(board,SIDE,1)
ELSEIF k=18 THEN FlipColumn(board,SIDE,2)
ELSEIF k=33 THEN Init(goal,board,SIDE) FI

UpdateStatus(goal,board,SIDE)
FI
OD
RETURN```
Output:

## Ada

This solution determines the size of the playground from the command line.

```with Ada.Text_IO, Ada.Command_Line, Ada.Numerics.Discrete_Random;

procedure Flip_Bits is

subtype Letter is Character range 'a' .. 'z';

Last_Col: constant letter := Ada.Command_Line.Argument(1)(1);
Last_Row: constant Positive := Positive'Value(Ada.Command_Line.Argument(2));

package Boolean_Rand is new Ada.Numerics.Discrete_Random(Boolean);
Gen: Boolean_Rand.Generator;

type Matrix is array
(Letter range 'a' .. Last_Col, Positive range 1 .. Last_Row) of Boolean;

function Rand_Mat return Matrix is
M: Matrix;
begin
for I in M'Range(1) loop
for J in M'Range(2) loop
M(I,J) := Boolean_Rand.Random(Gen);
end loop;
end loop;
return M;
end Rand_Mat;

function Rand_Mat(Start: Matrix) return Matrix is
M: Matrix := Start;
begin
for I in M'Range(1) loop
if  Boolean_Rand.Random(Gen) then
for J in M'Range(2) loop
M(I,J) := not M(I, J);
end loop;
end if;
end loop;
for I in M'Range(2) loop
if  Boolean_Rand.Random(Gen) then
for J in M'Range(1) loop
M(J,I) := not M(J, I);
end loop;
end if;
end loop;
return M;
end Rand_Mat;

procedure Print(Message: String; Mat: Matrix) is
package NIO is new Ada.Text_IO.Integer_IO(Natural);
begin
Ada.Text_IO.New_Line;
Ada.Text_IO.Put_Line(Message);
Ada.Text_IO.Put("   ");
for Ch in Matrix'Range(1) loop
Ada.Text_IO.Put(" " & Ch);
end loop;
Ada.Text_IO.New_Line;
for I in Matrix'Range(2) loop
NIO.Put(I, Width => 3);
for Ch in Matrix'Range(1) loop
Ada.Text_IO.Put(if Mat(Ch, I) then " 1" else " 0");
end loop;
Ada.Text_IO.New_Line;
end loop;
end Print;

Current, Target: Matrix;
Moves: Natural := 0;

begin
-- choose random Target and start ("Current") matrices
Boolean_Rand.Reset(Gen);
Target := Rand_Mat;
loop
Current := Rand_Mat(Target);
exit when Current /= Target;
end loop;
Print("Target:", Target);

-- print and modify Current matrix, until it is identical to Target
while Current /= Target loop
Moves := Moves + 1;
Print("Current move #" & Natural'Image(Moves), Current);
Ada.Text_IO.Put_Line("Flip row 1 .." & Positive'Image(Last_Row) &
" or column 'a' .. '" & Last_Col & "'");
declare
S: String := Ada.Text_IO.Get_Line;
function Let(S: String) return Character is (S(S'First));
function Val(Str: String) return Positive is (Positive'Value(Str));
begin
if Let(S) in 'a' .. Last_Col then
for I in Current'Range(2) loop
Current(Let(S), I) := not Current(Let(S), I);
end loop;
else
for I in Current'Range(1) loop
Current(I, Val(S)) := not Current(I, Val(S));
end loop;
end if;
end;
end loop;

-- summarize the outcome
Ada.Text_IO.Put_Line("Done after" & Natural'Image(Moves) & " Moves.");
end Flip_Bits;
```
Output:

For a 3*3-Matrix, the command line input is "c 3".

```>./flip_bits c 3

Target:
a b c
1 1 0 1
2 1 0 0
3 1 0 0

Current move # 1
a b c
1 1 0 0
2 1 0 1
3 0 1 0
Flip row 1 .. 3 or column 'a' .. 'c'
3

Current move # 2
a b c
1 1 0 0
2 1 0 1
3 1 0 1
Flip row 1 .. 3 or column 'a' .. 'c'
c
Done after 2 Moves.```

## APL

Works with: GNU APL
```#!/usr/local/bin/apl -s --

∇r←b FlipRow ix             ⍝ Flip a row
r←b
r[ix;]←~r[ix;]
∇

∇r←b FlipCol ix             ⍝ Flip a column
r←b
r[;ix]←~r[;ix]
∇

∇r←RandFlip b;ix            ⍝ Flip a random row or column
ix←?↑⍴b
→(2|?2)/col
r←b FlipRow ix ⋄ →0
col:    r←b FlipCol ix
∇

∇s←ttl ShowBoard b;d        ⍝ Add row, column indices and title to board
s←'-'⍪⍕(' ',⎕UCS 48+d),(⎕UCS 64+d←⍳↑⍴b)⍪b
s←((2⊃⍴s)↑ttl)⍪s
∇

∇b←MkBoard n                ⍝ Generate random board
b←(?(n,n)⍴2)-1
∇

∇Game;n;board;goal;moves;swaps;in;tgt
⍝⍝ Initialize
⎕RL←(2*32)|×/⎕TS    ⍝ random seed from time
→(5≠⍴⎕ARG)/usage    ⍝ check argument
→(~'0123456789'∧.∊⍨n←5⊃⎕ARG)/usage
→((3>n)∨8<n←⍎n)/usage
board←goal←MkBoard n    ⍝ Make a random board of the right size
swaps←4+?16             ⍝ 5 to 20 swaps
board←(RandFlip⍣swaps)board
moves←0
⎕←'*** Flip the bits! ***'
⎕←'----------------------'

⍝⍝ Print game state
state:  ⎕←''
⎕←'Swaps:',moves,'   Goal:',swaps
⎕←''
('Board'ShowBoard board),' ',' ',' ',' ','Goal'ShowBoard goal

⍝⍝ Handle move
⍞←'Press line or column to flip, or Q to quit: '
read:   in←32⊤∨1⎕FIO[41]1
→(in=⎕UCS'q')/0
→((97≤in)∧(tgt←in-96)≤n)/col
→((49≤in)∧(tgt←in-48)≤n)/row
→read
col:    ⍞←⎕UCS in ⋄ board←board FlipCol tgt ⋄ →check
row:    ⍞←⎕UCS in ⋄ board←board FlipRow tgt

⍝⍝ Check if player won
check:  →(board≡goal)/win
moves←moves+1
→state
win:    ⎕←'You win!'
→0
usage:  ⎕←'Usage:',⎕ARG[4],'[3..8]; number is board size.'
∇
Game
)OFF
```
Output:

Example game:

```\$ ./flip.apl 3
*** Flip the bits! ***
----------------------

Swaps: 0    Goal: 14

Board      Goal
-------    -------
A B C      A B C
1 0 0 1    1 1 0 1
2 0 1 0    2 0 0 1
3 1 0 1    3 0 0 1
Press line or column to flip, or Q to quit: 2

Swaps: 1    Goal: 14

Board      Goal
-------    -------
A B C      A B C
1 0 0 1    1 1 0 1
2 1 0 1    2 0 0 1
3 1 0 1    3 0 0 1
Press line or column to flip, or Q to quit: a
You win!

\$```

## AutoHotkey

 This example is incomplete. Understood comment on why output is missing, but this is to make that fact more prominent. Please ensure that it meets all task requirements and remove this message.

Uploads are currently disabled, so since a GUI is used, I can't show an example.

```size := 3 ; max 26
Gui, Add, Button, , O
Loop, %size%
{
x := chr(A_Index+64)
If x = A
Loop, %size%
Gui, Add, Button, y+4 gFlip, % A_Index
Gui, Add, Button, ym gFlip, % x
Loop, %size%
{
y := A_Index
Random, %x%%y%, 0, 1
Gui, Add, Edit, v%x%%y% ReadOnly, % %x%%y%
}
}
Gui, Add, Text, ym, Moves:`nTarget:
Loop, %size%
{
x := chr(A_Index+64)
Loop, %size%
{
y := A_Index
Gui, Add, Edit, % y=1 ? x="A" ? "xp+0 ym+30" : "x+14 ym+30" : "" . "ReadOnly vt" x y, % t%x%%y% := %x%%y%
}
}Gui, Add, Text, xp-18 ym w30 Right vMoves, % Moves:=1

; randomize
While (i < size)
{
Random, z, 1, %size%
Random, x, 0, 1
z := x ? chr(z+64) : z
Solution .= z ; to cheat
If Flip(z, size)
i := 0 ; ensure we are not at the solution
Else
i++ ; count
}
Gui, Show, NA
Return

Flip(z, size) {
Loop, %size%
{
If z is alpha
GuiControl, , %z%%A_Index%, % %z%%A_Index% := !%z%%A_Index%
Else
{
AIndex := chr(A_Index+64)
GuiControl, , %AIndex%%z%, % %AIndex%%z% := !%AIndex%%z%
}
}
Loop, %size%
{
x := chr(A_Index+64)
Loop, %size%
{
y := A_Index
If (%x%%y% != t%x%%y%)
Return 0
}
}
Return 1
}

Flip:
GuiControl, , Moves, % Moves++
If Flip(A_GuiControl, size)
{
Msgbox Success in %Moves% moves!
Reload
}
Return

ButtonO:
Reload
Return

GuiEscape:
GuiClose:
ExitApp
Return
```

## BASIC

```10 DEFINT A-Z
20 PRINT "*** FLIP THE BITS ***"
30 INPUT "Board size";S
40 IF S<3 OR S>8 THEN PRINT "3 <= size <= 8": GOTO 30
50 RANDOMIZE
60 DIM B(S,S),G(S,S)
70 FOR X=1 TO S
80 FOR Y=1 TO S
90 B=INT(.5+RND(1))
100 B(X,Y)=B: G(X,Y)=B
110 NEXT Y,X
120 FOR A=0 TO 10+2*INT(10*RND(1))
130 R=INT(.5+RND(1))
140 N=1+INT(S*RND(1))
150 GOSUB 500
160 NEXT A: M=0
170 PRINT: M=M+1
180 PRINT " ==BOARD==";TAB(20);" ==GOAL=="
190 PRINT "   ";: GOSUB 400
200 PRINT TAB(20);"   ";: GOSUB 400
210 FOR N=1 TO S
220 FOR A=0 TO 1
230 PRINT TAB(A*20);CHR\$(64+N);". ";
240 FOR C=1 TO S: IF A THEN B=G(C,N) ELSE B=B(C,N)
250 PRINT USING "# ";B;
260 NEXT C,A
270 PRINT
280 NEXT N
290 PRINT
300 LINE INPUT "Enter row or column: ";I\$
310 IF LEN(I\$)<>1 THEN 300 ELSE C=ASC(I\$) OR 32
320 IF C<97 THEN N=C-48:R=0 ELSE N=C-96:R=1
330 IF N<1 OR N>S THEN 300 ELSE GOSUB 500
340 W=1=1
350 FOR X=1 TO S:FOR Y=1 TO S
360 W=W AND (B(X,Y)=G(X,Y))
370 NEXT Y,X
380 IF W THEN PRINT:PRINT "You win! Moves:";M:END
390 GOTO 170
400 FOR I=1 TO S: PRINT USING "# ";I;: NEXT I: RETURN
500 IF R THEN 510 ELSE 520
510 FOR I=1 TO S: B(I,N)=1-B(I,N): NEXT I: RETURN
520 FOR I=1 TO S: B(N,I)=1-B(N,I): NEXT I: RETURN
```
Output:
```*** FLIP THE BITS ***
Board size? 3
Random number seed (-32768 to 32767)? 1

==BOARD==          ==GOAL==
1 2 3              1 2 3
A. 1 0 1           A. 1 1 0
B. 1 1 1           B. 0 1 1
C. 1 1 1           C. 1 0 0

Enter row or column: 2

==BOARD==          ==GOAL==
1 2 3              1 2 3
A. 1 1 1           A. 1 1 0
B. 1 0 1           B. 0 1 1
C. 1 0 1           C. 1 0 0

Enter row or column: 3

==BOARD==          ==GOAL==
1 2 3              1 2 3
A. 1 1 0           A. 1 1 0
B. 1 0 0           B. 0 1 1
C. 1 0 0           C. 1 0 0

Enter row or column: B

You win! Moves: 3 ```

## BCPL

```get "libhdr"
static \$( randstate = ? \$)

let rand() = valof
\$(  randstate := random(randstate)
resultis randstate >> 7
\$)

let showboard(size, board, goal) be
\$(  writes(" == BOARD == ")
for i=1 to 19 do wrch(' ')
writes(" == GOAL ==*N")

for i=1 to 2
\$(  writes("  ")
for j=1 to size do writef(" %N",j)
test i=1 for j=1 to 30-2*size do wrch(' ') or wrch('*N')
\$)

for row=0 to size-1 for i=1 to 2
\$(  writef("%C.", 'A'+row)
for col=0 to size-1 do
writef(" %N", (i=1->board,goal)!(row*size+col))
test i=1 for j=1 to 30-2*size do wrch(' ') or wrch('*N')
\$)
\$)

let readmove(size) = valof
\$(  let ch = ? and x = ?
writes("Enter row or column, or Q to quit: ")
ch := rdch()
unless ch = '*N' x := rdch() repeatuntil x = '*N'
ch := ch | 32;
if ch = 'q' | ch = endstreamch finish
if 0 <= (ch-'1') < size | 0 <= (ch-'a') < size resultis ch
\$) repeat

let flip(size, board, n, col) be
test col
do flipcol(size, board, n)
or fliprow(size, board, n)
and flipcol(size, board, n) be
for i=0 to size-1 do
board!(i*size+n) := 1-board!(i*size+n)
and fliprow(size, board, n) be
for i=0 to size-1 do
board!(n*size+i) := 1-board!(n*size+i)

let makegoal(size, goal) be
for i=0 to size*size-1 do goal!i := rand() & 1

let makeboard(size, board, goal) be
\$(  for i=0 to size*size-1 do board!i := goal!i
for i=0 to 10+2*(rand() & 15) do
flip(size, board, rand() rem size, rand() & 1)
\$)

let win(size, board, goal) = valof
\$(  for i=0 to size*size-1
unless board!i = goal!i resultis false
resultis true
\$)

let play(size, board, goal) be
\$(  let moves = 0 and move = ?
\$(  showboard(size, board, goal)
wrch('*N')
if win(size, board, goal)
\$(  writef("You won in %N moves!*N", moves)
return
\$)
moves := moves + 1
move := readmove(size)
test '0' <= move <= '9'
do flipcol(size, board, move-'1')
or fliprow(size, board, move-'a')
\$) repeat
\$)

let start() be
\$(  let board = vec 63 and goal = vec 63
let size = ?
writef("****** FLIP THE BITS *******N")
\$(  writef("Size (3-8)? ")
size := readn()
\$) repeatuntil 3 <= size <= 8
writef("Random number seed? ")
randstate := readn()
wrch('*N')
makegoal(size, goal)
makeboard(size, board, goal)
play(size, board, goal)
\$)```
Output:
```*** FLIP THE BITS ***
Size (3-8)? 3
Random number seed? 0

== BOARD ==                     == GOAL ==
1 2 3                           1 2 3
A. 1 0 1                        A. 0 1 1
B. 0 1 0                        B. 1 0 0
C. 1 0 0                        C. 1 0 1

Enter row or column, or Q to quit: 3
== BOARD ==                     == GOAL ==
1 2 3                           1 2 3
A. 1 0 0                        A. 0 1 1
B. 0 1 1                        B. 1 0 0
C. 1 0 1                        C. 1 0 1

Enter row or column, or Q to quit: A
== BOARD ==                     == GOAL ==
1 2 3                           1 2 3
A. 0 1 1                        A. 0 1 1
B. 0 1 1                        B. 1 0 0
C. 1 0 1                        C. 1 0 1

Enter row or column, or Q to quit: B
== BOARD ==                     == GOAL ==
1 2 3                           1 2 3
A. 0 1 1                        A. 0 1 1
B. 1 0 0                        B. 1 0 0
C. 1 0 1                        C. 1 0 1

You won in 3 moves!```

## C

```#include <stdio.h>
#include <stdlib.h>

int i, j;

void fliprow(int **b, int sz, int n)
{
for(i = 0; i < sz; i++)
b[n+1][i] = !b[n+1][i];
}

void flipcol(int **b, int sz, int n)
{
for(i = 1; i <= sz; i++)
b[i][n] = !b[i][n];
}

void initt(int **t, int sz)
{
for(i = 1; i <= sz; i++)
for(j = 0; j < sz; j++)
t[i][j] = rand()%2;
}

void initb(int **t, int **b, int sz)
{
for(i = 1; i <= sz; i++)
for(j = 0; j < sz; j++)
b[i][j] = t[i][j];

for(i = 1; i <= sz; i++)
fliprow(b, sz, rand()%sz+1);
for(i = 0; i < sz; i++)
flipcol(b, sz, rand()%sz);
}

void printb(int **b, int sz)
{
printf(" ");
for(i = 0; i < sz; i++)
printf(" %d", i);
printf("\n");

for(i = 1; i <= sz; i++)
{
printf("%d", i-1);
for(j = 0; j < sz; j++)
printf(" %d", b[i][j]);
printf("\n");
}

printf("\n");
}

int eq(int **t, int **b, int sz)
{
for(i = 1; i <= sz; i++)
for(j = 0; j < sz; j++)
if(b[i][j] != t[i][j])
return 0;
return 1;
}

void main()
{
int sz = 3;
int eql = 0;
int mov = 0;
int **t = malloc(sz*(sizeof(int)+1));
for(i = 1; i <= sz; i++)
t[i] = malloc(sz*sizeof(int));

int **b = malloc(sz*(sizeof(int)+1));
for(i = 1; i <= sz; i++)
b[i] = malloc(sz*sizeof(int));
char roc;
int n;
initt(t, sz);
initb(t, b, sz);

while(eq(t, b, sz))
initb(t, b, sz);

while(!eql)
{
printf("Target: \n");
printb(t, sz);
printf("Board: \n");
printb(b, sz);
printf("What to flip: ");
scanf(" %c", &roc);
scanf(" %d", &n);

switch(roc)
{
case 'r':
fliprow(b, sz, n);
break;
case 'c':
flipcol(b, sz, n);
break;
default:
perror("Please specify r or c and an number");
break;
}

printf("Moves Taken: %d\n", ++mov);

if(eq(t, b, sz))
{
printf("You win!\n");
eql = 1;
}
}
}
```
Output:
```Target:
0 1 2
0 1 0 1
1 1 1 1
2 0 0 1

Board:
0 1 2
0 1 0 0
1 1 1 0
2 1 1 1

What to flip: r2
Moves Taken: 1
Target:
0 1 2
0 1 0 1
1 1 1 1
2 0 0 1

Board:
0 1 2
0 1 0 0
1 1 1 0
2 0 0 0

What to flip: c2
Moves Taken: 2
You win!
```

## C++

```#include <time.h>
#include <iostream>
#include <string>

typedef unsigned char byte;
using namespace std;

class flip
{
public:
flip() { field = 0; target = 0; }
void play( int w, int h ) { wid = w; hei = h; createField(); gameLoop(); }

private:
void gameLoop()
{
int moves = 0;
while( !solved() )
{
display(); string r; cout << "Enter rows letters and/or column numbers: "; cin >> r;
for( string::iterator i = r.begin(); i != r.end(); i++ )
{
byte ii = ( *i );
if( ii - 1 >= '0' && ii - 1 <= '9' ) { flipCol( ii - '1' ); moves++; }
else if( ii >= 'a' && ii <= 'z' ) { flipRow( ii - 'a' ); moves++; }
}
}
cout << endl << endl << "** Well done! **" << endl << "Used " << moves << " moves." << endl << endl;
}

void display()
{ system( "cls" ); output( "TARGET:", target ); output( "YOU:", field ); }

void output( string t, byte* f )
{
cout << t << endl;
cout << " "; for( int x = 0; x < wid; x++ ) cout << " " << static_cast<char>( x + '1' ); cout << endl;
for( int y = 0; y < hei; y++ )
{
cout << static_cast<char>( y + 'a' ) << " ";
for( int x = 0; x < wid; x++ )
cout << static_cast<char>( f[x + y * wid] + 48 ) << " ";
cout << endl;
}
cout << endl << endl;
}

bool solved()
{
for( int y = 0; y < hei; y++ )
for( int x = 0; x < wid; x++ )
if( target[x + y * wid] != field[x + y * wid] ) return false;
return true;
}

void createTarget()
{
for( int y = 0; y < hei; y++ )
for( int x = 0; x < wid; x++ )
if( frnd() < .5f ) target[x + y * wid] = 1;
else target[x + y * wid] = 0;
memcpy( field, target, wid * hei );
}

void flipCol( int c )
{ for( int x = 0; x < hei; x++ ) field[c + x * wid] = !field[c + x * wid]; }

void flipRow( int r )
{ for( int x = 0; x < wid; x++ ) field[x + r * wid] = !field[x + r * wid]; }

void calcStartPos()
{
int flips = ( rand() % wid + wid + rand() % hei + hei ) >> 1;
for( int x = 0; x < flips; x++ )
{ if( frnd() < .5f ) flipCol( rand() % wid ); else flipRow( rand() % hei ); }
}

void createField()
{
if( field ){ delete [] field; delete [] target; }
int t = wid * hei; field = new byte[t]; target = new byte[t];
memset( field, 0, t ); memset( target, 0, t ); createTarget();
while( true ) { calcStartPos(); if( !solved() ) break; }
}

float frnd() { return static_cast<float>( rand() ) / static_cast<float>( RAND_MAX ); }

byte* field, *target; int wid, hei;
};

int main( int argc, char* argv[] )
{ srand( time( NULL ) ); flip g; g.play( 3, 3 ); return system( "pause" ); }
```
Output:
```TARGET:
1 2 3
a 0 1 0
b 0 1 0
c 0 1 0

YOU:
1 2 3
a 0 0 0
b 0 0 0
c 1 1 1

Enter rows letters and/or column numbers: 2c

** Well done! **
Used 2 moves.
```

## Clojure

```(defn cols [board]
(mapv vec (apply map list board)))

(defn flipv [v]
(mapv #(if (> % 0) 0 1) v))

(defn flip-row [board n]
(assoc board n (flipv (get board n))))

(defn flip-col [board n]
(cols (flip-row (cols board) n)))

(defn play-rand [board n]
(if (= n 0)
board
(let [f (if (= (rand-int 2) 0) flip-row flip-col)]
(recur (f board (rand-int (count board))) (dec n)))))

(defn rand-binary-vec [size]
(vec (take size (repeatedly #(rand-int 2)))))

(defn rand-binary-board [size]
(vec (take size (repeatedly #(rand-binary-vec size)))))

(defn numbers->letters [coll]
(map #(char (+ 97 %)) coll))

(defn column-labels [size]
(apply str (interpose " " (numbers->letters (range size)))))

(defn print-board [board]
(let [size (count board)]
(println "\t " (column-labels size))
(dotimes [n size] (println (inc n) "\t" (board n)))))

(defn key->move [key]
(let [start (int (first key))
row-value (try (Long/valueOf key) (catch NumberFormatException e))]
(cond
(<= 97 start 122) [:col (- start 97)]
(<= 65 start 90) [:col (- start 65)]
(> row-value 0) [:row (dec row-value)]
:else nil)))

(defn play-game [target-board current-board n]
(println "\nTurn " n)
(print-board current-board)
(if (= target-board current-board)
(println "You win!")
(let [move (key->move (read-line))
axis (first move)
idx (second move)]
(cond
(= axis :row) (play-game target-board (flip-row current-board idx) (inc n))
(= axis :col) (play-game target-board (flip-col current-board idx) (inc n))
:else (println "Quitting!")))))

(defn -main
"Flip the Bits Game!"
[& args]
(if-not (empty? args)
(let [target-board (rand-binary-board (Long/valueOf (first args)))]
(println "Target")
(print-board target-board)
(play-game target-board (play-rand target-board 3) 0))))
```
Output:
```Target
a b c
1        [1 0 1]
2        [0 1 1]
3        [0 1 1]

Turn  0
a b c
1        [1 0 1]
2        [0 1 1]
3        [1 0 0]
3

Turn  1
a b c
1        [1 0 1]
2        [0 1 1]
3        [0 1 1]
You win!
```

## D

Translation of: Python
```import std.stdio, std.random, std.ascii, std.string, std.range,
std.algorithm, std.conv;

enum N = 3; // Board side.
static assert(N <= lowercase.length);
enum columnIDs = lowercase[0 .. N];
alias Board = ubyte[N][N];

void flipBits(ref Board board, in size_t count=1) {
foreach (immutable _; 0 .. count)
board[uniform(0, \$)][uniform(0, \$)] ^= 1;
}

void notRow(ref Board board, in size_t i) pure nothrow {
board[i][] ^= 1;
}

void notColumn(ref Board board, in size_t i) pure nothrow {
foreach (ref row; board)
row[i] ^= 1;
}

Board generateGameBoard(in ref Board target) {
// board is generated with many flips, to keep parity unchanged.
Board board = target;
while (board == target)
foreach (immutable _; 0 .. 2 * N)
[&notRow, &notColumn][uniform(0, 2)](board, uniform(0, N));
return board;
}

void show(in ref Board board, in string comment) {
comment.writeln;
writefln("     %-(%c %)", columnIDs);
foreach (immutable j, const row; board)
writefln("  %2d %-(%d %)", j + 1, row);
}

void main() {
"T prints the target, and Q exits.\n".writeln;
// Create target and flip some of its bits randomly.
Board target;
flipBits(target, uniform(0, N) + 1);
show(target, "Target configuration is:");

auto board = generateGameBoard(target);
immutable prompt = format("  1-%d / %s-%s to flip, or T, Q: ",
N, columnIDs[0], columnIDs.back);
uint move = 1;
while (board != target) {
show(board, format("\nMove %d:", move));
prompt.write;
immutable ans = readln.strip;

if (ans.length == 1 && columnIDs.canFind(ans)) {
board.notColumn(columnIDs.countUntil(ans));
move++;
} else if (iota(1, N + 1).map!text.canFind(ans)) {
board.notRow(ans.to!uint - 1);
move++;
} else if (ans == "T") {
show(target, "Target configuration is:");
} else if (ans == "Q") {
return "Game stopped.".writeln;
} else
writefln("  Wrong input '%s'. Try again.\n", ans.take(9));
}

"\nWell done!".writeln;
}
```
Output:
```T prints the target, and Q exits.

Target configuration is:
a b c
1 1 1 1
2 0 0 0
3 0 0 0

Move 1:
a b c
1 1 0 0
2 1 0 0
3 1 0 0
1-3 / a-c to flip, or T, Q: a

Move 2:
a b c
1 0 0 0
2 0 0 0
3 0 0 0
1-3 / a-c to flip, or T, Q: 1

Well done!```

## Elixir

Works with: Elixir version 1.1
Translation of: Ruby
```defmodule Flip_game do
@az  Enum.map(?a..?z, &List.to_string([&1]))
@in2i Enum.concat(Enum.map(1..26, fn i -> {to_string(i), i} end),
Enum.with_index(@az) |> Enum.map(fn {c,i} -> {c,-i-1} end))
|> Enum.into(Map.new)

def play(n) when n>2 do
target = generate_target(n)
display(n, "Target: ", target)
board = starting_config(n, target)
play(n, target, board, 1)
end

def play(n, target, board, moves) do
display(n, "Board: ", board)
ans = IO.gets("row/column to flip: ") |> String.strip |> String.downcase
new_board = case @in2i[ans] do
i when i in 1..n   -> flip_row(n, board, i)
i when i in -1..-n -> flip_column(n, board, -i)
_ -> IO.puts "invalid input: #{ans}"
board
end
if target == new_board do
display(n, "Board: ", new_board)
IO.puts "You solved the game in #{moves} moves"
else
IO.puts ""
play(n, target, new_board, moves+1)
end
end

defp generate_target(n) do
for i <- 1..n, j <- 1..n, into: Map.new, do: {{i, j}, :rand.uniform(2)-1}
end

defp starting_config(n, target) do
Enum.concat(1..n, -1..-n)
|> Enum.take_random(n)
|> Enum.reduce(target, fn x,acc ->
if x>0, do: flip_row(n, acc, x),
else: flip_column(n, acc, -x)
end)
end

defp flip_row(n, board, row) do
Enum.reduce(1..n, board, fn col,acc ->
Map.update!(acc, {row,col}, fn bit -> 1 - bit end)
end)
end

defp flip_column(n, board, col) do
Enum.reduce(1..n, board, fn row,acc ->
Map.update!(acc, {row,col}, fn bit -> 1 - bit end)
end)
end

defp display(n, title, board) do
IO.puts title
IO.puts "   #{Enum.join(Enum.take(@az,n), " ")}"
Enum.each(1..n, fn row ->
:io.fwrite "~2w ", [row]
IO.puts Enum.map_join(1..n, " ", fn col -> board[{row, col}] end)
end)
end
end

Flip_game.play(3)
```
Output:
```Target:
a b c
1 1 0 1
2 0 1 1
3 0 1 1
Board:
a b c
1 0 1 1
2 0 1 0
3 1 0 1
row/column to flip: 2

Board:
a b c
1 0 1 1
2 1 0 1
3 1 0 1
row/column to flip: a

Board:
a b c
1 1 1 1
2 0 0 1
3 0 0 1
row/column to flip: b
Board:
a b c
1 1 0 1
2 0 1 1
3 0 1 1
You solved the game in 3 moves
```

## FOCAL

```01.10 T "FLIP THE BITS"!"-------------"!!;S M=0
01.20 A "SIZE",N;I (N-2)1.2;I (8-N)1.2
01.30 F I=0,N*N-1;D 3.2;S G(I)=A;S B(I)=A
01.35 D 3.3;S L=FITR(A*5)*2+6;F K=0,L;D 3.1;S Z=A;D 3.2;D 4.4
01.40 S A=0;F I=0,N*N-1;S A=A+FABS(G(I)-B(I))
01.42 T "MOVES",%3,M,!;S M=M+1
01.45 I (0-A)1.5;T !"YOU WIN!"!;Q
01.50 D 2
01.55 A "FLIP ROW (A) OR COLUMN (B)",A;S A=A-1;I (1-A)1.5
01.60 A "WHICH",Z;S Z=Z-1;I (N-A)1.6
01.65 D 4.4;G 1.4

02.10 T "--BOARD--";F A=1,N*2-5;T " "
02.14 T "--GOAL--"!" ";F A=0,N-1;T " ";D 5
02.15 T "    ";F A=0,N-1;T " ";D 5
02.20 F R=0,N-1;S A=R;T !;D 2.4;T "   ";D 2.5
02.30 T !!;R
02.40 D 5;F C=0,N-1;D 2.6
02.50 D 5;F C=0,N-1;D 2.7
02.60 I (B(R*N+C)-1)2.8;T " 1"
02.70 I (G(R*N+C)-1)2.8;T " 1"
02.80 T " 0"

03.10 D 3.3;S A=FITR(A*N)
03.20 D 3.3;S A=FITR(A+0.5)
03.30 S A=FABS(FRAN())*10;S A=A-FITR(A)

04.40 I (A-1)4.5,4.6
04.50 F I=0,N-1;S B(Z*N+I)=1-B(Z*N+I)
04.60 F I=0,N-1;S B(I*N+Z)=1-B(I*N+Z)

05.10 I (A-7)5.2;T "H";R
05.20 I (A-6)5.3;T "G";R
05.30 I (A-5)5.4;T "F";R
05.40 I (A-4)5.5;T "E";R
05.50 I (A-3)5.6;T "D";R
05.60 I (A-2)5.7;T "C";R
05.70 I (A-1)5.8;T "B";R
05.80 T "A"```
Output:
```FLIP THE BITS
-------------

SIZE:3
MOVES=   0
--BOARD-- --GOAL--
A B C     A B C
A 1 0 1   A 0 1 1
B 1 1 0   B 0 0 0
C 0 0 1   C 0 0 0

FLIP ROW (A) OR COLUMN (B):A
WHICH:A
MOVES=   1
--BOARD-- --GOAL--
A B C     A B C
A 0 1 0   A 0 1 1
B 1 1 0   B 0 0 0
C 0 0 1   C 0 0 0

FLIP ROW (A) OR COLUMN (B):A
WHICH:B
MOVES=   2
--BOARD-- --GOAL--
A B C     A B C
A 0 1 0   A 0 1 1
B 0 0 1   B 0 0 0
C 0 0 1   C 0 0 0

FLIP ROW (A) OR COLUMN (B):B
WHICH:C
MOVES=   3

YOU WIN!```

## Forth

Works with: gforth version 0.7.3

### 8x8 board in 64 bits Version

Board size limited to 8x8, stored in only one cell (64 bits) variable.

```require random.fs

0 value board-size
variable target
variable board
variable moves

: moves-reset 0 moves ! ;
: moves+ 1 moves +! ;
: .moves ." You have made " moves @ . ." moves." ;

: target-gen ( -- )  rnd target ! ;

: row-flip ( n -- )
8 * 255 swap lshift
board @ xor board ! ;

: column-flip ( n -- )
1 swap lshift
8 0 do dup 8 lshift or loop
board @ xor board ! ;

: target>board ( -- )  target @ board ! ;

: board-shuffle ( -- )
board-size dup * 0 do
board-size random 2 random if row-flip else column-flip then
loop ;

: ask-move ( -- char )
cr ." choose row [0-"  board-size [char] 0 + 1- emit
." ] or column [a-" board-size [char] a + 1- emit
." ]: "
key ;

: do-move ( char -- )
dup emit
dup [char] a dup board-size + within
if dup [char] a - column-flip
else
dup [char] 0 dup board-size + within
if dup [char] 0 - row-flip
else ." - this move is not permitted!"
then then
cr drop
;

: .header ( -- )  cr ." Target: " board-size 2 * spaces ." Board:" ;
: .column-header ( -- )  board-size 0 do i [char] a + emit space loop ;
: .row-header ( n -- )  . ." - " ;
: .row ( board@ n -- )  dup .row-header 8 * rshift board-size 0 do dup 1 and . 2/ loop drop ;
: .boards
.header cr
4 spaces .column-header  8 spaces  .column-header cr
board-size 0 do
target @ i .row  4 spaces  board @ i .row cr
loop
;

: ?win ( -- f )
0  board-size 0 do 2* 1+ loop
board-size 1 do dup 8 lshift or loop
dup target @ and
swap board @ and =
;

: game-loop
begin
.boards .moves
ask-move do-move moves+
?win until
." You win after " moves @ . ." moves!"
;

: flip-bit-game ( n -- )
to board-size
target-gen  target>board  board-shuffle
moves-reset
game-loop
;
```
Output:
```3 flip-bit-game
Target:       Board:
a b c         a b c
0 - 0 0 1     0 - 1 0 0
1 - 1 0 1     1 - 1 1 1
2 - 1 0 0     2 - 0 0 1
You have made 0 moves.
choose row [0-2] or column [a-c]: 0

Target:       Board:
a b c         a b c
0 - 0 0 1     0 - 0 1 1
1 - 1 0 1     1 - 1 1 1
2 - 1 0 0     2 - 0 0 1
You have made 1 moves.
choose row [0-2] or column [a-c]: 2

Target:       Board:
a b c         a b c
0 - 0 0 1     0 - 0 1 1
1 - 1 0 1     1 - 1 1 1
2 - 1 0 0     2 - 1 1 0
You have made 2 moves.
choose row [0-2] or column [a-c]: b
You win after 3 moves! ok
```

### board in a cells array Version

No size limitation. Board stored in a cells array (use of 64 bits for a bit...). Memory not freed.

```require random.fs

0 value board-size
0 value target
0 value board
variable moves

: moves-reset 0 moves ! ;
: moves+ 1 moves +! ;
: .moves ." You have made " moves @ . ." moves." ;

: allot-board ( -- addr ) here board-size dup * cells allot ;

: target-gen ( -- )
board-size dup * 0 do
2 random [char] 0 +  target i cells + !
loop
;

: row-flip ( board n -- )
board-size * cells +
dup board-size cells + swap do
i dup @ 1 xor swap !
cell +loop
;

: column-flip ( board n -- )
cells +
dup board-size dup * cells + swap do
i dup @ 1 xor swap !
board-size cells +loop
;

: target>board ( -- )
board-size dup * cells  0 do
target i + @  board i + !
cell +loop
;

: board-shuffle ( -- )
board-size dup * 0 do
board board-size random 2 random if row-flip else column-flip then
loop
;

: ask-move ( -- char )
cr ." choose row [0-"  board-size [char] 0 + 1- emit
." ] or column [a-" board-size [char] a + 1- emit
." ]: "
key ;

: do-move ( char -- )
dup emit
dup [char] a dup board-size + within
if dup board swap [char] a - column-flip
else
dup [char] 0 dup board-size + within
if dup board swap [char] 0 - row-flip
else ." - this move is not permitted!"
then then
cr drop
;

: .header ( -- )  cr ." Target: " board-size 2 * spaces ." Board:" ;
: .column-header ( -- )  board-size 0 do i [char] a + emit space loop ;
: .row-header ( n -- )  . ." - " ;
: .bit ( board row col -- )  board-size * + cells + @ emit space ;
: .row ( board n -- )  dup .row-header  board-size 0 do  2dup i swap .bit  loop 2drop ;
: .boards
.header cr
4 spaces .column-header  8 spaces  .column-header cr
board-size 0 do
target i .row  4 spaces  board i .row cr
loop
;

: ?win ( -- f )
board-size dup * 0 do
target i cells + @  board i cells + @
<> if false unloop exit then
loop true
;

: game-loop
begin
.boards .moves
ask-move do-move moves+
?win until
." You win after " moves @ . ." moves!"
;

: flip-bit-game ( n -- )
to board-size
allot-board to target
allot-board to board
target-gen
target>board
board-shuffle
moves-reset
game-loop
;
```
Output:
```3 flip-bit-game
Target:       Board:
a b c         a b c
0 - 0 0 0     0 - 1 0 1
1 - 0 1 1     1 - 0 0 1
2 - 1 1 0     2 - 0 1 1
You have made 0 moves.
choose row [0-2] or column [a-c]: 0

Target:       Board:
a b c         a b c
0 - 0 0 0     0 - 0 1 0
1 - 0 1 1     1 - 0 0 1
2 - 1 1 0     2 - 0 1 1
You have made 1 moves.
choose row [0-2] or column [a-c]: b

Target:       Board:
a b c         a b c
0 - 0 0 0     0 - 0 0 0
1 - 0 1 1     1 - 0 1 1
2 - 1 1 0     2 - 0 0 1
You have made 2 moves.
choose row [0-2] or column [a-c]: 2
You win after 3 moves! ok
```

## Fortran

This version uses some routines (like rand(), srand() and date_and_time()) from the GNU Fortran compiler. Formats are used to print data on the screen in an appropriate manner. The number of rows (or columns) is a variable and the current implementation allows for any number between 1 and 10. Incorrect inputs are also verified.

```!Implemented by Anant Dixit (October 2014)
program flipping_bits
implicit none
character(len=*), parameter :: cfmt = "(A3)", ifmt = "(I3)"
integer :: N, i, j, io, seed(8), moves, input
logical, allocatable :: Brd(:,:), Trgt(:,:)
logical :: solved
double precision :: r

do
write(*,*) 'Enter the number of squares (between 1 and 10) you would like: '
read(*,*,iostat=io) N
if(N.gt.0 .and. N.le.10 .and. io.eq.0) exit
write(*,*) 'Please, an integer between 1 and 10'
end do

allocate(Brd(N,N),Trgt(N,N))
call date_and_time(values=seed)
call srand(1000*seed(7)+seed(8)+60000*seed(6))
do i = 1,N
do j = 1,N
r = rand()
if(r.gt.0.5D0) then
Brd(i,j) = .TRUE.
Trgt(i,j) = .TRUE.
else
Brd(i,j) = .FALSE.
Trgt(i,j) = .FALSE.
end if
end do
end do
! Random moves taken by the program to `create' a target
moves = N
do i = 1,moves
r = 1+2.0D0*dble(N)*rand() - 1.0D-17 !Only to make sure that the number is between 1 and 2N (less than 2N-1)
if(floor(r).le.N) then
do j = 1,N
Trgt(floor(r),j) = .NOT.Trgt(floor(r),j)
end do
else
r = r-N
do j = 1,N
Trgt(j,floor(r)) = .NOT.Trgt(j,floor(r))
end do
end if
end do

!This part checks if the target and the starting configurations are same or not.
do
input = N
call next_move(Brd,Trgt,N,input,solved)
call next_move(Brd,Trgt,N,input,solved)
if(solved) then
r = 1+2.0D0*dble(N)*rand() - 1.0D-17
if(floor(r).le.N) then
do j = 1,N
Trgt(floor(r),j) = .NOT.Trgt(floor(r),j)
end do
else
r = r-N
do j = 1,N
Trgt(j,floor(r)) = .NOT.Trgt(j,floor(r))
end do
end if
else
exit
end if
end do

write(*,*) 'Welcome to the Flipping Bits game!'
write(*,*) 'You have the current position'

moves = 0
call display(Brd,Trgt,N)
input = N
do
write(*,*) 'Number of moves so far:', moves
write(*,*) 'Select the column or row you wish to flip: '
read(*,*,iostat=io) input
if(io.eq.0 .and. input.gt.0 .and. input.le.(2*N)) then
moves = moves+1
write(*,*) 'Flipping ', input
call next_move(Brd,Trgt,N,input,solved)
call display(Brd,Trgt,N)
if(solved) exit
else
write(*,*) 'Please enter a valid column or row number. To quit, press Ctrl+C!'
end if
end do

write(*,*) 'Congratulations! You finished the game!'
write(*,ifmt,advance='no') moves
write(*,*) ' moves were taken by you!!'
deallocate(Brd,Trgt)
end program

subroutine display(Brd,Trgt,N)
implicit none
!arguments
integer :: N
logical :: Brd(N,N), Trgt(N,N)
!local
character(len=*), parameter :: cfmt = "(A3)", ifmt = "(I3)"
integer :: i, j
write(*,*) 'Current Configuration: '
do i = 0,N
if(i.eq.0) then
write(*,cfmt,advance='no') 'R/C'
write(*,cfmt,advance='no') ' | '
else
write(*,ifmt,advance='no') i
end if
end do
write(*,*)
do i = 0,N
if(i.eq.0) then
do j = 0,N+2
write(*,cfmt,advance='no') '---'
end do
else
write(*,ifmt,advance='no') i+N
write(*,cfmt,advance='no') ' | '
do j = 1,N
if(Brd(i,j)) then
write(*,ifmt,advance='no') 1
else
write(*,ifmt,advance='no') 0
end if
end do
end if
write(*,*)
end do

write(*,*)
write(*,*)

write(*,*) 'Target Configuration'
do i = 0,N
if(i.eq.0) then
write(*,cfmt,advance='no') 'R/C'
write(*,cfmt,advance='no') ' | '
else
write(*,ifmt,advance='no') i
end if
end do
write(*,*)
do i = 0,N
if(i.eq.0) then
do j = 0,N+2
write(*,cfmt,advance='no') '---'
end do
else
write(*,ifmt,advance='no') i+N
write(*,cfmt,advance='no') ' | '
do j = 1,N
if(Trgt(i,j)) then
write(*,ifmt,advance='no') 1
else
write(*,ifmt,advance='no') 0
end if
end do
end if
write(*,*)
end do
write(*,*)
write(*,*)
end subroutine

subroutine next_move(Brd,Trgt,N,input,solved)
implicit none
!arguments
integer :: N, input
logical :: Brd(N,N), Trgt(N,N), solved
!others
integer :: i,j

if(input.gt.N) then
input = input-N
do i = 1,N
Brd(input,i) = .not.Brd(input,i)
end do
else
do i = 1,N
Brd(i,input) = .not.Brd(i,input)
end do
end if
solved = .TRUE.
do i = 1,N
do j = 1,N
if( (.not.Brd(i,j).and.Trgt(i,j)) .or. (Brd(i,j).and..not.Trgt(i,j)) ) then
solved = .FALSE.
exit
end if
end do
if(.not.solved) exit
end do
end subroutine
```

Example:

```./flipping_bits
Enter the number of squares (between 1 and 10) you would like:
3
Welcome to the Flipping Bits game!
You have the current position
Current Configuration:
R/C |   1  2  3
------------
4 |   1  0  0
5 |   1  1  0
6 |   0  0  0

Target Configuration
R/C |   1  2  3
------------
4 |   1  1  1
5 |   1  0  1
6 |   1  0  0

Select the column or row you wish to flip:
2
Current Configuration:
R/C |   1  2  3
------------
4 |   1  1  0
5 |   1  0  0
6 |   0  1  0

Target Configuration
R/C |   1  2  3
------------
4 |   1  1  1
5 |   1  0  1
6 |   1  0  0

Select the column or row you wish to flip:
3
Current Configuration:
R/C |   1  2  3
------------
4 |   1  1  1
5 |   1  0  1
6 |   0  1  1

Target Configuration
R/C |   1  2  3
------------
4 |   1  1  1
5 |   1  0  1
6 |   1  0  0

Select the column or row you wish to flip:
6
Current Configuration:
R/C |   1  2  3
------------
4 |   1  1  1
5 |   1  0  1
6 |   1  0  0

Target Configuration
R/C |   1  2  3
------------
4 |   1  1  1
5 |   1  0  1
6 |   1  0  0

Congratulations! You finished the game!
3  moves were taken by you!!
```

## FreeBASIC

Translation of: QB64
```Dim Shared As Integer celdasXLado, contarMovs
Dim Shared As String movsValidos, inicioBS, actualBS, objetivoBS

Sub mostrarTablero (fila As Integer, columna As Integer, junto As String, titulo As String)
Dim As Integer i, j

Locate fila - 1, columna: Print titulo
For i = 1 To celdasXLado
Locate fila, columna + 2 * (i-1) + 3: Print Mid(movsValidos, i, 1);
Next i
Print
For i = 1 To celdasXLado
Locate fila + i, columna - 1: Print Str(i);
For j = 1 To celdasXLado
Locate fila + i, columna + 2 * j: Print " " + Mid(junto, (i-1) * celdasXLado + j, 1);
Next j
Print
Next i
End Sub

Sub mostrarEstado
Color  9: mostrarTablero 2, 2, actualBS, "Current:"
Color 12: mostrarTablero 2, 2 + 2 * celdasXLado + 6, objetivoBS, " Target:"
Color 13: Print !"\n Number of moves taken so far is " + Str(contarMovs)
Color 14
End Sub

Function Pistas() As String 'compare the currentB to targetB and suggest letter or digit or done
Dim As Integer i, j
Dim As Boolean flag = False
Dim As String r, actualBitS, objetivoBitS

For i = 1 To 2 * celdasXLado 'check cols first then rows as listed in movsValidos
r = Mid(movsValidos, i, 1)
If i <= celdasXLado Then
actualBitS = Mid(actualBS, i, 1): objetivoBitS = Mid(objetivoBS, i, 1)
If actualBitS <> objetivoBitS Then flag = False: Exit For
Else
j = i - celdasXLado
actualBitS   = Mid(actualBS, (j - 1) * celdasXLado + 1, 1)
objetivoBitS = Mid(objetivoBS, (j - 1) * celdasXLado + 1, 1)
If actualBitS <> objetivoBitS Then flag = False: Exit For
End If
Next i
Pistas = Iif(flag, r, "Done?")
End Function

Sub Centrar (fila As Integer, texto As String) 'center print at fila
Locate fila, (80 - Len(texto)) / 2: Print texto;
End Sub

Sub vcls 'print the screen to file then clear it
Dim As String sc(23), scan
Dim As Integer lineas, t, final, i

For lineas = 1 To 23
For t = 1 To 80: scan &= Chr(Screen(lineas, t)): Next t
sc(lineas) = Rtrim(scan)
scan = ""
Next lineas
For final = 23 To 1 Step -1
If sc(final) <> "" Then Exit For
Next final
Print #3, ""
For i = 1 To final: Print #3, sc(i): Next i
Print #3, "": Print #3, String(80, "-"): Cls
End Sub

Function TeclaPulsada() As String 'just want printable characters
Dim As String KBD = ""

While Len(KBD) = 0
KBD = Inkey
If Len(KBD) Then 'press something so respond
If Len(KBD) = 2 Or Asc(KBD) > 126 Or Asc(KBD) < 32 Then KBD = "*"
End If
Wend
Return KBD
End Function

Function inicioTablero() As String
Dim As String r

For i As Integer = 1 To celdasXLado ^ 2
r &= Ltrim(Str(Int(Rnd * 2)))
Next i
Return r
End Function

Sub hacerMovim (moveS As String)
Dim As Uinteger ac = Asc(moveS)
Dim As Integer i, columna, fila
Dim As String bitS

If ac > 96 Then 'letter
columna = ac - 96
For i = 1 To celdasXLado
bitS = Mid(actualBS, (i - 1) * celdasXLado + columna, 1)
Mid(actualBS, (i-1) * celdasXLado + columna, 1) = Iif(bitS = "0", "1", "0")
Next
Else 'number
fila = ac - 48
For i = 1 To celdasXLado
bitS = Mid(actualBS, (fila-1) * celdasXLado + i, 1)
Mid(actualBS, (fila-1) * celdasXLado + i, 1) = Iif(bitS = "0", "1", "0")
Next i
End If
End Sub

Function hacerObjetivo() As String
While actualBS = inicioBS
For i As Integer = 1 To celdasXLado * celdasXLado
Dim As String mS = Mid(movsValidos, Int(Rnd * Len(movsValidos)) + 1, 1)
hacerMovim mS
Next i
Wend
Return actualBS
End Function

Sub Intro
Dim As Integer i
Dim As String inS

Close
Open "Copy Flipping Bits Game.txt" For Output As #3
celdasXLado = 0: movsValidos = "": contarMovs = 0
Color 9: Centrar 3, "Flipping Bits Game (with AI!)  JHG 31/05/2023"
Color 5
Centrar 5, "You will be presented with a square board marked Current and"
Centrar 6, "another marked Target. The object of the game is to match"
Centrar 7, "the Current board to Target in the least amount of moves."
Centrar 9, "To make a move, enter a letter for a column to flip or"
Centrar 10, "a digit for a fila to flip. In a flip, all 1's are"
Centrar 11, "changed to 0's and all 0's changed to 1's."
Centrar 13, "You may enter 0 or q at any time to quit."
Centrar 14, "You may press ? when prompted for move to get a hint."
Centrar 15, "You may press ! to have the program solve the puzzle."
Color 14: Print: Print
While celdasXLado < 2 Or celdasXLado > 9
Locate Csrlin, 13: Print "Please press how many cells you want per side 2 to 9 > ";
inS = TeclaPulsada: Print inS : Sleep .4
If inS = "0" Or inS = "q" Then End Else celdasXLado = Val(inS)
Wend
vcls
For i = 1 To celdasXLado: movsValidos = movsValidos + Chr(96 + i)  : Next i
For i = 1 To celdasXLado: movsValidos = movsValidos + Ltrim(Str(i)): Next i
inicioBS = inicioTablero
actualBS = inicioBS
objetivoBS = hacerObjetivo
actualBS = inicioBS
End Sub

Sub MenuPrincipal
Dim As String SiNo, mS, mvS
Dim As Boolean mostrarSolucion = False, salir = False

Do
mostrarEstado
If actualBS = objetivoBS Then 'game done!
Print !"\n Congratulations, done in"; contarMovs; " moves."
Print !"\n Press y for yes, if you want to start over > ";
SiNo = TeclaPulsada: Print SiNo: Sleep .4: vcls
If SiNo = "y" Then Intro Else salir = True
Else 'get next move
mS = " "
While Instr(movsValidos, mS) = 0
Print !"\n Press a lettered column or a numbered fila to flip (or 0,q,?,!) > ";
mS = TeclaPulsada: Print mS: Sleep .4
If mS = "!" Then
mostrarSolucion = True: mS = " ": Exit While
Elseif mS = "?" Then mS = " ": Centrar Csrlin, "Hint: " + Pistas
Elseif mS = "0" Or mS = "q" Then vcls: Close: End
Elseif mS = "" Then mS = " "
End If
Wend
If mostrarSolucion Then 'run the solution from hints function
mostrarSolucion = False: mvS = Pistas
Centrar Csrlin + 1, "For the next move, the AI has chosen: " + mvS
Centrar Csrlin + 1, "Running the solution with 4 sec screen sleeps..."
Sleep 4: vcls
While mvS <> "Done?"
contarMovs += 1
hacerMovim mvS
mostrarEstado
mvS = Pistas
Centrar Csrlin + 1, "For the next move, the AI has chosen: " + mvS
Centrar Csrlin + 1, "Running the solution with 4 sec screen sleeps..."
Sleep 4: vcls
Wend
mostrarEstado
Centrar Csrlin + 1, "Done! Current board matches Target"
Centrar Csrlin + 1, "Press y for yes, if you want to start over: > "
SiNo = TeclaPulsada: Print SiNo: Sleep .4: vcls
If SiNo = "y" Then Intro Else salir = True
Else
vcls
contarMovs += 1
hacerMovim mS
End If
End If
Loop Until salir
Close
End Sub

'--- Programa Principal ---
Randomize Timer
Intro
MenuPrincipal
End
'--------------------------
```
Output:
`Similar to QB64 entry.`

## Go

```package main

import (
"fmt"
"math/rand"
"time"
)

func main() {

rand.Seed(time.Now().UnixNano())

var n int = 3 // Change to define board size
var moves int = 0

a := make([][]int, n)
for i := range a {
a[i] = make([]int, n)
for j := range a {
a[i][j] = rand.Intn(2)
}
}

b := make([][]int, len(a))
for i := range a {
b[i] = make([]int, len(a[i]))
copy(b[i], a[i])
}

for i := rand.Intn(100); i > 0 || compareSlices(a, b) == true; i-- {
b = flipCol(b, rand.Intn(n) + 1)
b = flipRow(b, rand.Intn(n) + 1)
}

fmt.Println("Target:")
drawBoard(a)
fmt.Println("\nBoard:")
drawBoard(b)

var rc rune
var num int

for {
for{
fmt.Printf("\nFlip row (r) or column (c)  1 .. %d (c1, ...): ", n)
_, err := fmt.Scanf("%c%d", &rc, &num)
if err != nil {
fmt.Println(err)
continue
}
if num < 1 || num > n {
fmt.Println("Wrong command!")
continue
}
break
}

switch rc {
case 'c':
fmt.Printf("Column %v will be flipped\n", num)
flipCol(b, num)
case 'r':
fmt.Printf("Row %v will be flipped\n", num)
flipRow(b, num)
default:
fmt.Println("Wrong command!")
continue
}

moves++
fmt.Println("\nMoves taken: ", moves)

fmt.Println("Target:")
drawBoard(a)
fmt.Println("\nBoard:")
drawBoard(b)

if compareSlices(a, b) {
fmt.Printf("Finished. You win with %d moves!\n", moves)
break
}
}
}

func drawBoard (m [][]int) {
fmt.Print("   ")
for i := range m {
fmt.Printf("%d ", i+1)
}
for i := range m {
fmt.Println()
fmt.Printf("%d ", i+1)
for _, val := range m[i] {
fmt.Printf(" %d", val)
}
}
fmt.Print("\n")
}

func flipRow(m [][]int, row int) ([][]int) {
for j := range m {
m[row-1][j] ^= 1
}
return m
}

func flipCol(m [][]int, col int) ([][]int) {
for j := range m {
m[j][col-1] ^= 1
}
return m
}

func compareSlices(m [][]int, n[][]int) bool {
o := true
for i := range m {
for j := range m {
if m[i][j] != n[i][j] { o = false }
}
}
return o
}
```
Output:
```Target:
1 2 3
1  0 1 1
2  0 1 1
3  1 1 1

Board:
1 2 3
1  1 0 0
2  1 0 0
3  1 1 1

Flip row (r) or column (c)  1 .. 3 (c1, ...): r1
Row 1 will be flipped

Moves taken:  1
Target:
1 2 3
1  0 1 1
2  0 1 1
3  1 1 1

Board:
1 2 3
1  0 1 1
2  1 0 0
3  1 1 1

Flip row (r) or column (c)  1 .. 3 (c1, ...): r2
Row 2 will be flipped

Moves taken:  2
Target:
1 2 3
1  0 1 1
2  0 1 1
3  1 1 1

Board:
1 2 3
1  0 1 1
2  0 1 1
3  1 1 1
Finished. You win with 2 moves!```

## Haskell

Maximum game size is 9x9 because the array indices are the characters 1 until 9.

```import Data.List (intersperse)

import System.Random (randomRIO)

import Data.Array (Array, (!), (//), array, bounds)

import Control.Monad (zipWithM_, replicateM, foldM, when)

type Board = Array (Char, Char) Int

flp :: Int -> Int
flp 0 = 1
flp 1 = 0

numRows, numCols :: Board -> String
numRows t =
let ((a, _), (b, _)) = bounds t
in [a .. b]

numCols t =
let ((_, a), (_, b)) = bounds t
in [a .. b]

flipRow, flipCol :: Board -> Char -> Board
flipRow t r =
let e =
[ (ix, flp (t ! ix))
| ix <- zip (repeat r) (numCols t) ]
in t // e

flipCol t c =
let e =
[ (ix, flp (t ! ix))
| ix <- zip (numRows t) (repeat c) ]
in t // e

printBoard :: Board -> IO ()
printBoard t = do
let rows = numRows t
cols = numCols t
f 0 = '0'
f 1 = '1'
p r xs = putStrLn \$ [r, ' '] ++ intersperse ' ' (map f xs)
putStrLn \$ "  " ++ intersperse ' ' cols
zipWithM_
p
rows
[ [ t ! (y, x)
| x <- cols ]
| y <- rows ]

-- create a random goal board, and flip rows and columns randomly
-- to get a starting board
setupGame :: Char -> Char -> IO (Board, Board)
setupGame sizey sizex
-- random cell value at (row, col)
= do
let mk rc = (\v -> (rc, v)) <\$> randomRIO (0, 1)
rows = ['a' .. sizey]
cols = ['1' .. sizex]
goal <-
array (('a', '1'), (sizey, sizex)) <\$>
mapM
mk
[ (r, c)
| r <- rows
, c <- cols ]
start <-
do let change :: Board -> Int -> IO Board
-- flip random row
change t 0 = flipRow t <\$> randomRIO ('a', sizey)
-- flip random col
change t 1 = flipCol t <\$> randomRIO ('1', sizex)
numMoves <- randomRIO (3, 15) -- how many flips (3 - 15)
-- determine if rows or cols are flipped
moves <- replicateM numMoves \$ randomRIO (0, 1)
-- make changes and get a starting board
foldM change goal moves
if goal /= start -- check if boards are different
then return (goal, start) -- all ok, return both boards
else setupGame sizey sizex -- try again

main :: IO ()
main = do
putStrLn "Select a board size (1 - 9).\nPress any other key to exit."
sizec <- getChar
when (sizec `elem` ['1' .. '9']) \$
do let size = read [sizec] - 1
(g, s) <- setupGame (['a' ..] !! size) (['1' ..] !! size)
turns g s 0
where
turns goal current moves = do
putStrLn "\nGoal:"
printBoard goal
putStrLn "\nBoard:"
printBoard current
when (moves > 0) \$
putStrLn \$ "\nYou've made " ++ show moves ++ " moves so far."
putStrLn \$
"\nFlip a row (" ++
numRows current ++ ") or a column (" ++ numCols current ++ ")"
v <- getChar
if v `elem` numRows current
then check \$ flipRow current v
else if v `elem` numCols current
then check \$ flipCol current v
else tryAgain
where
check t =
if t == goal
then putStrLn \$ "\nYou've won in " ++ show (moves + 1) ++ " moves!"
else turns goal t (moves + 1)
tryAgain = do
putStrLn ": Invalid row or column."
turns goal current moves
```
Output:
```Select a board size (1 - 9).
Press any other key to exit.
3
Goal:
1 2 3
a 1 1 0
b 1 0 0
c 0 0 0

Board:
1 2 3
a 1 0 0
b 1 1 0
c 1 0 1

Flip a row (abc) or a column (123)
2
Goal:
1 2 3
a 1 1 0
b 1 0 0
c 0 0 0

Board:
1 2 3
a 1 1 0
b 1 0 0
c 1 1 1

You've made 1 moves so far.

Flip a row (abc) or a column (123)
c
You've won in 2 moves!```

## J

Using J's command line as the game ui:

```start=:3 :0
Moves=:0
N=:i.y
Board=: ?2\$~,~y
'fr fc'=. (2,y)\$}.#:(+?&.<:@<:)2x^2*y
End=: fr~:fc~:"1 Board
Board;End
)

abc=:'abcdefghij'
move=:3 :0
fc=. N e.abc i. y ([-.-.)abc
fr=. N e._-.~_ "."0 abc-.~":y
Board=: fr~:fc~:"1 Board
smoutput (":Moves=:Moves++/fr,fc),' moves'
if. Board-:End do.
'yes'
else.
Board;End
end.
)
```

Example:

```   start 3
┌─────┬─────┐
│1 1 1│1 0 1│
│1 1 0│0 1 1│
│1 0 0│0 0 1│
└─────┴─────┘
move 'b2'
2 moves
┌─────┬─────┐
│1 0 1│1 0 1│
│1 0 0│0 1 1│
│0 0 1│0 0 1│
└─────┴─────┘
move '1'
3 moves
yes
```

Note that any size game may be generated but this version only recognizes column flips for the first ten columns.

## Java

Works with: Java version 8
```import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

public class FlippingBitsGame extends JPanel {
final int maxLevel = 7;
final int minLevel = 3;

private Random rand = new Random();
private int[][] grid, target;
private Rectangle box;
private int n = maxLevel;
private boolean solved = true;

FlippingBitsGame() {
setPreferredSize(new Dimension(640, 640));
setBackground(Color.white);
setFont(new Font("SansSerif", Font.PLAIN, 18));

box = new Rectangle(120, 90, 400, 400);

startNewGame();

addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
if (solved) {
startNewGame();
} else {
int x = e.getX();
int y = e.getY();

if (box.contains(x, y))
return;

if (x > box.x && x < box.x + box.width) {
flipCol((x - box.x) / (box.width / n));

} else if (y > box.y && y < box.y + box.height)
flipRow((y - box.y) / (box.height / n));

if (solved(grid, target))
solved = true;

printGrid(solved ? "Solved!" : "The board", grid);
}
repaint();
}
});
}

void startNewGame() {
if (solved) {

n = (n == maxLevel) ? minLevel : n + 1;

grid = new int[n][n];
target = new int[n][n];

do {
shuffle();

for (int i = 0; i < n; i++)
target[i] = Arrays.copyOf(grid[i], n);

shuffle();

} while (solved(grid, target));

solved = false;
printGrid("The target", target);
printGrid("The board", grid);
}
}

void printGrid(String msg, int[][] g) {
System.out.println(msg);
for (int[] row : g)
System.out.println(Arrays.toString(row));
System.out.println();
}

boolean solved(int[][] a, int[][] b) {
for (int i = 0; i < n; i++)
if (!Arrays.equals(a[i], b[i]))
return false;
return true;
}

void shuffle() {
for (int i = 0; i < n * n; i++) {
if (rand.nextBoolean())
flipRow(rand.nextInt(n));
else
flipCol(rand.nextInt(n));
}
}

void flipRow(int r) {
for (int c = 0; c < n; c++) {
grid[r][c] ^= 1;
}
}

void flipCol(int c) {
for (int[] row : grid) {
row[c] ^= 1;
}
}

void drawGrid(Graphics2D g) {
g.setColor(getForeground());

if (solved)
g.drawString("Solved! Click here to play again.", 180, 600);
else
g.drawString("Click next to a row or a column to flip.", 170, 600);

int size = box.width / n;

for (int r = 0; r < n; r++)
for (int c = 0; c < n; c++) {
g.setColor(grid[r][c] == 1 ? Color.blue : Color.orange);
g.fillRect(box.x + c * size, box.y + r * size, size, size);
g.setColor(getBackground());
g.drawRect(box.x + c * size, box.y + r * size, size, size);
g.setColor(target[r][c] == 1 ? Color.blue : Color.orange);
g.fillRect(7 + box.x + c * size, 7 + box.y + r * size, 10, 10);
}
}

@Override
public void paintComponent(Graphics gg) {
super.paintComponent(gg);
Graphics2D g = (Graphics2D) gg;
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);

drawGrid(g);
}

public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setTitle("Flipping Bits Game");
f.setResizable(false);
f.add(new FlippingBitsGame(), BorderLayout.CENTER);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
});
}
}
```
```The target
[0, 1, 0]
[0, 1, 0]
[0, 1, 0]

The board
[0, 1, 1]
[0, 1, 1]
[0, 1, 1]

Solved!
[0, 1, 0]
[0, 1, 0]
[0, 1, 0]```

## JavaScript

```function numOfRows(board) { return board.length; }
function numOfCols(board) { return board[0].length; }
function boardToString(board) {
// First the top-header
var header = '   ';
for (var c = 0; c < numOfCols(board); c++)
header += c + ' ';

// Then the side-header + board
var sideboard = [];
for (var r = 0; r < numOfRows(board); r++) {
sideboard.push(r + ' [' + board[r].join(' ') + ']');
}

return header + '\n' + sideboard.join('\n');
}
function flipRow(board, row) {
for (var c = 0; c < numOfCols(board); c++) {
board[row][c] = 1 - board[row][c];
}
}
function flipCol(board, col) {
for (var r = 0; r < numOfRows(board); r++) {
board[r][col] = 1 - board[r][col];
}
}

function playFlippingBitsGame(rows, cols) {
rows = rows | 3;
cols = cols | 3;
var targetBoard = [];
var manipulatedBoard = [];
// Randomly generate two identical boards.
for (var r = 0; r < rows; r++) {
targetBoard.push([]);
manipulatedBoard.push([]);
for (var c = 0; c < cols; c++) {
targetBoard[r].push(Math.floor(Math.random() * 2));
manipulatedBoard[r].push(targetBoard[r][c]);
}
}
// Naive-scramble one of the boards.
while (boardToString(targetBoard) == boardToString(manipulatedBoard)) {
var scrambles = rows * cols;
while (scrambles-- > 0) {
if (0 == Math.floor(Math.random() * 2)) {
flipRow(manipulatedBoard, Math.floor(Math.random() * rows));
}
else {
flipCol(manipulatedBoard, Math.floor(Math.random() * cols));
}
}
}
// Get the user to solve.
alert(
'Try to match both boards.\n' +
'Enter `r<num>` or `c<num>` to manipulate a row or col or enter `q` to quit.'
);
var input = '', letter, num, moves = 0;
while (boardToString(targetBoard) != boardToString(manipulatedBoard) && input != 'q') {
input = prompt(
'Target:\n' + boardToString(targetBoard) +
'\n\n\n' +
'Board:\n' + boardToString(manipulatedBoard)
);
try {
letter = input.charAt(0);
num = parseInt(input.slice(1));
if (letter == 'q')
break;
if (isNaN(num)
|| (letter != 'r' && letter != 'c')
|| (letter == 'r' && num >= rows)
|| (letter == 'c' && num >= cols)
) {
throw new Error('');
}
if (letter == 'r') {
flipRow(manipulatedBoard, num);
}
else {
flipCol(manipulatedBoard, num);
}
moves++;
}
catch(e) {
alert('Uh-oh, there seems to have been an input error');
}
}
if (input == 'q') {
alert('~~ Thanks for playing ~~');
}
else {
alert('Completed in ' + moves + ' moves.');
}
}
```
```Try to match both boards.
Enter `r<num>` or `c<num>` to manipulate a row or col or enter `q` to quit.

Target:
0 1 2
0 [0 1 1]
1 [1 0 0]
2 [1 0 1]

Board:
0 1 2
0 [0 0 0]
1 [1 1 1]
2 [0 0 1]
r2

Target:
0 1 2
0 [0 1 1]
1 [1 0 0]
2 [1 0 1]

Board:
0 1 2
0 [0 0 0]
1 [0 0 0]
2 [0 0 1]
c0

Target:
0 1 2
0 [0 1 1]
1 [1 0 0]
2 [1 0 1]

Board:
0 1 2
0 [1 0 0]
1 [1 0 0]
2 [1 0 1]
r0

Completed in 3 moves.```

## Julia

```module FlippingBitsGame

using Printf, Random
import Base.size, Base.show, Base.==

struct Configuration
M::BitMatrix
end

Base.size(c::Configuration) = size(c.M)
function Base.show(io::IO, conf::Configuration)
M = conf.M
nrow, ncol = size(M)
print(io, " " ^ 3)
for c in 1:ncol
@printf(io, "%3i", c)
end
println(io, "\n", " " ^ 4, "-" ^ 3ncol)
for r in 1:nrow
@printf(io, "%2i |", r)
for c in 1:ncol
@printf(io, "%2c ", ifelse(M[r, c], 'T', 'F'))
end
println(io)
end
return nothing
end
Base.:(==)(a::Configuration, b::Configuration) = a.M == b.M

struct Index{D}
i::Int
end
const ColIndex = Index{:C}
const RowIndex = Index{:R}

function flipbits!(conf::Configuration, c::ColIndex)
col = @view conf.M[:, c.i]
@. col = !col
return conf
end
function flipbits!(conf::Configuration, r::RowIndex)
row = @view conf.M[r.i, :]
@. row = !row
return conf
end

randomconfig(nrow::Integer, ncol::Integer) = Configuration(bitrand(nrow, ncol))

function randommoves!(conf::Configuration, nflips::Integer)
nrow, ncol = size(conf)
for _ in Base.OneTo(nflips)
if rand() < 0.5
flipbits!(conf, ColIndex(rand(1:ncol)))
else
flipbits!(conf, RowIndex(rand(1:nrow)))
end
end
return conf
end

function play()
nrow::Int, ncol::Int = 0, 0
while nrow < 2 || ncol < 2
print("Insert the size of the matrix (nrow [> 1] *space* ncol [> 1]):")
nrow, ncol = parse.(Int, split(readline()))
end
mat = randomconfig(nrow, ncol)
obj = deepcopy(mat)
randommoves!(obj, 100)
nflips = 0
while mat != obj
println("\n", nflips, " flips until now.")
println("Current configuration:")
println(mat)
println("Objective configuration:")
println(obj)
print("Insert R[ind] to flip row, C[ind] to flip a column, Q to quit: ")
line  = readline()
input = match(r"([qrc])(\d+)"i, line)
if input ≢ nothing && all(input.captures .≢ nothing)
dim = Symbol(uppercase(input.captures[1]))
ind = Index{dim}(parse(Int, input.captures[2]))
flipbits!(mat, ind)
nflips += 1
elseif occursin("q", line)
println("\nSEE YOU SOON!")
return
else
println("\nINPUT NOT VALID, RETRY!\n")
end
end
println("\nSUCCED! In ", nflips, " flips.")
println(mat)
return
end

end  # module FlippingBitsGame

using .FlippingBitsGame

FlippingBitsGame.play()
```
Output:
```Insert the size of the matrix (nrow [> 1] *space* ncol [> 1]):3 3

0 flips until now.
Current configuration:
1  2  3
---------
1 | F  F  F
2 | T  F  T
3 | F  F  T

Objective configuration:
1  2  3
---------
1 | F  F  T
2 | F  T  T
3 | F  F  F

Insert R[ind] to flip row, C[ind] to flip a column, Q to quit: c3

1 flips until now.
Current configuration:
1  2  3
---------
1 | F  F  T
2 | T  F  F
3 | F  F  F

Objective configuration:
1  2  3
---------
1 | F  F  T
2 | F  T  T
3 | F  F  F

Insert R[ind] to flip row, C[ind] to flip a column, Q to quit: r2

SUCCED! In 2 flips.
1  2  3
---------
1 | F  F  T
2 | F  T  T
3 | F  F  F
```

## Kotlin

```// version 1.1.3

import java.util.Random

val rand = Random()
val target = Array(3) { IntArray(3) { rand.nextInt(2) } }
val board  = Array(3) { IntArray(3) }

fun flipRow(r: Int) {
for (c in 0..2) board[r][c] = if (board[r][c] == 0) 1 else 0
}

fun flipCol(c: Int) {
for (r in 0..2) board[r][c] = if (board[r][c] == 0) 1 else 0
}

/** starting from the target we make 9 random row or column flips */
fun initBoard() {
for (i in 0..2) {
for (j in 0..2) board[i][j] = target[i][j]
}
repeat(9) {
val rc = rand.nextInt(2)
if (rc == 0)
flipRow(rand.nextInt(3))
else
flipCol(rand.nextInt(3))
}
}

fun printBoard(label: String, isTarget: Boolean = false) {
val a = if (isTarget) target else board
println("\$label:")
println("  | a b c")
println("---------")
for (r in 0..2) {
print("\${r + 1} |")
for (c in 0..2) print(" \${a[r][c]}")
println()
}
println()
}

fun gameOver(): Boolean {
for (r in 0..2) {
for (c in 0..2) if (board[r][c] != target[r][c]) return false
}
return true
}

fun main(args: Array<String>) {
// initialize board and ensure it differs from the target i.e. game not already over!
do {
initBoard()
}
while(gameOver())

printBoard("TARGET", true)
printBoard("OPENING BOARD")
var flips = 0

do {
var isRow = true
var n = -1
do {
print("Enter row number or column letter to be flipped: ")
val input = readLine()!!
val ch = if (input.isNotEmpty()) input[0].toLowerCase() else '0'
if (ch !in "123abc") {
println("Must be 1, 2, 3, a, b or c")
continue
}
if (ch in '1'..'3') {
n = ch.toInt() - 49
}
else {
isRow = false
n = ch.toInt() - 97
}
}
while (n == -1)

flips++
if (isRow) flipRow(n) else flipCol(n)
val plural = if (flips == 1) "" else "S"
printBoard("\nBOARD AFTER \$flips FLIP\$plural")
}
while (!gameOver())

val plural = if (flips == 1) "" else "s"
println("You've succeeded in \$flips flip\$plural")
}
```
Output:

A sample game:

```TARGET:
| a b c
---------
1 | 0 1 0
2 | 0 1 0
3 | 1 1 1

OPENING BOARD:
| a b c
---------
1 | 1 0 0
2 | 0 1 1
3 | 0 0 1

Enter row number or column letter to be flipped: 1

BOARD AFTER 1 FLIP:
| a b c
---------
1 | 0 1 1
2 | 0 1 1
3 | 0 0 1

Enter row number or column letter to be flipped: 3

BOARD AFTER 2 FLIPS:
| a b c
---------
1 | 0 1 1
2 | 0 1 1
3 | 1 1 0

Enter row number or column letter to be flipped: c

BOARD AFTER 3 FLIPS:
| a b c
---------
1 | 0 1 0
2 | 0 1 0
3 | 1 1 1

You've succeeded in 3 flips!
```

## Lua

```target, board, moves, W, H = {}, {}, 0, 3, 3

function getIndex( i, j ) return i + j * W - W end

function flip( d, r )
function invert( a ) if a == 1 then return 0 end return 1 end
local idx
if d == 1 then
for i = 1, W do
idx = getIndex( i, r )
board[idx] = invert( board[idx] )
end
else
for i = 1, H do
idx = getIndex( r, i )
board[idx] = invert( board[idx] )
end
end
moves = moves + 1
end
function createTarget()
target, board = {}, {}
local idx
for j = 1, H do
for i = 1, W do
idx = getIndex( i, j )
if math.random() < .5 then target[idx] = 0
else target[idx] = 1
end
board[idx] = target[idx]
end
end
for i = 1, 103 do
if math.random() < .5 then flip( 1, math.random( H ) )
else flip( 2, math.random( W ) )
end
end
moves = 0
end
function getUserInput()
io.write( "Input row and/or column: " ); local r = io.read()
local a
for i = 1, #r do
a = string.byte( r:sub( i, i ):lower() )
if a >= 48 and a <= 57 then flip( 2, a - 48 ) end
if a >= 97 and a <= string.byte( 'z' ) then flip( 1, a - 96 ) end
end
end
function solved()
local idx
for j = 1, H do
for i = 1, W do
idx = getIndex( i, j )
if target[idx] ~= board[idx] then return false end
end
end
return true
end
function display()
local idx
io.write( "\nTARGET\n   " )
for i = 1, W do io.write( string.format( "%d  ", i ) ) end; print()
for j = 1, H do
io.write( string.format( "%s  ", string.char( 96 + j ) ) )
for i = 1, W do
idx = getIndex( i, j )
io.write( string.format( "%d  ", target[idx] ) )
end; io.write( "\n" )
end
io.write( "\nBOARD\n   " )
for i = 1, W do io.write( string.format( "%d  ", i ) ) end; print()
for j = 1, H do
io.write( string.format( "%s  ", string.char( 96 + j ) ) )
for i = 1, W do
idx = getIndex( i, j )
io.write( string.format( "%d  ", board[idx] ) )
end; io.write( "\n" )
end
io.write( string.format( "Moves: %d\n", moves ) )
end
function play()
while true do
createTarget()
repeat
display()
getUserInput()
until solved()
display()
io.write( "Very well!\nPlay again(Y/N)? " );
if io.read():lower() ~= "y" then return end
end
end
--[[entry point]]--
math.randomseed( os.time() )
play()
```
Output:
```TARGET
1  2  3
a  0  0  0
b  0  0  0
c  1  0  0

BOARD
1  2  3
a  1  1  0
b  0  0  1
c  0  1  0
Moves: 0
Input row and/or column: 3ac

TARGET
1  2  3
a  0  0  0
b  0  0  0
c  1  0  0

BOARD
1  2  3
a  0  0  0
b  0  0  0
c  1  0  0
Moves: 3
Very well!
Play again(Y/N)?
```

## Maple

Click here to play this game online.

```FlippingBits := module()
export ModuleApply;
local gameSetup, flip, printGrid, checkInput;
local board;

gameSetup := proc(n)
local r, c, i, toFlip, target;
randomize():
target := Array( 1..n, 1..n, rand(0..1) );
board := copy(target);
for i to rand(3..9)() do
toFlip := [0, 0];
toFlip[1] := StringTools[Random](1, "rc");
toFlip[2] := convert(rand(1..n)(), string);
flip(toFlip);
end do;
return target;
end proc;

flip := proc(line)
local i, lineNum;
lineNum := parse(op(line[2..-1]));
for i to upperbound(board)[1] do
if line[1] = "R" then
board[lineNum, i] := `if`(board[lineNum, i] = 0, 1, 0);
else
board[i, lineNum] := `if`(board[i, lineNum] = 0, 1, 0);
end if;
end do;
return NULL;
end proc;

printGrid := proc(grid)
local r, c;
for r to upperbound(board)[1] do
for c to upperbound(board)[1] do
printf("%a ", grid[r, c]);
end do;
printf("\n");
end do;
printf("\n");
return NULL;
end proc;

checkInput := proc(input)
try
if input[1] = "" then
return false, "";
elif not input[1] = "R" and not input[1] = "C" then
return false, "Please start with 'r' or 'c'.";
elif not type(parse(op(input[2..-1])), posint) then
error;
elif parse(op(input[2..-1])) < 1 or parse(op(input[2..-1])) > upperbound(board)[1] then
return false, "Row or column number too large or too small.";
end if;
catch:
return false, "Please indicate a row or column number."
end try;
return true, "";
end proc;

ModuleApply := proc(n)
local gameOver, toFlip, target, answer, restart;
restart := true;
while restart do
target := gameSetup(n);
while ArrayTools[IsEqual](target, board) do
target := gameSetup(n);
end do;
gameOver := false;
while not gameOver do
printf("The Target:\n");
printGrid(target);
printf("The Board:\n");
printGrid(board);
if ArrayTools[IsEqual](target, board) then
printf("You win!! Press enter to play again or type END to quit.\n\n");
answer := StringTools[UpperCase](readline());
gameOver := true;
if answer = "END" then
restart := false
end if;
else
toFlip := ["", ""];
while not checkInput(toFlip)[1]  and not gameOver do
ifelse (not op(checkInput(toFlip)[2..-1]) = "", printf("%s\n\n", op(checkInput(toFlip)[2..-1])), NULL);
printf("Please enter a row or column to flip. (ex: r1 or c2) Press enter for a new game or type END to quit.\n\n");
answer := StringTools[UpperCase](readline());
if answer = "END" or answer = "" then
gameOver := true;
if answer = "END" then
restart := false;
end if;
end if;
toFlip := [substring(answer, 1), substring(answer, 2..-1)];
end do;
if not gameOver then
flip(toFlip);
end if;
end if;
end do;
end do;
printf("Game Over!\n");
end proc;
end module:

FlippingBits(3);```
Output:
```The Target:
1 1 1
1 1 1
1 0 1

The Board:
0 1 1
0 1 1
0 0 1

Please enter a row or column to flip. (ex: r1 or c2) Press enter for a new game or type END to quit.

The Target:
1 1 1
1 1 1
1 0 1

The Board:
1 1 1
1 1 1
1 0 1

You win!! Press enter to play again or type END to quit.
```

## Mathematica /Wolfram Language

```ClearAll[PermuteState]
PermuteState[state_, {rc_, n_Integer}] := Module[{s},
s = state;
Switch[rc, "R",
s[[n]] = 1 - s[[n]],
"C",
s[[All, n]] = 1 - s[[All, n]]
];
s
]
SeedRandom[1337];
n = 3;
goalstate = state = RandomChoice[{0, 1}, {n, n}];
While[goalstate == state,
permutations = {RandomChoice[{"C", "R"}, 20], RandomInteger[{1, n}, 20]} // Transpose;
state = Fold[PermuteState, state, permutations];
];
i = 0;
history = {state};
Grid[goalstate, ItemSize -> {5, 3}, Frame -> True]
b1 = Button["", state = PermuteState[state, {"C", #}];
AppendTo[history, state]; i++;
If[state === goalstate, MessageDialog["You Won!"];
Print[Grid[#, Frame -> True]] & /@ history]] & /@ Range[n];
b2 = Button["", state = PermuteState[state, {"R", #}];
AppendTo[history, state]; i++;
If[state === goalstate, MessageDialog["You Won!"];
Print[Grid[#, Frame -> True]] & /@ history]] & /@ Range[n];
Dynamic[Grid[
Prepend[MapThread[Prepend, {state, b2}],
Prepend[b1, Row[{"Flips: ", i}]]], Frame -> True
]]
```
Output:
```0	1	0
1	0	0
1	0	1

0	0	0
1	1	0
1	1	1

1	0	0
0	1	0
0	1	1

1	0	0
1	0	1
0	1	1

0	1	1
1	0	1
0	1	1```

## MATLAB

Size can be passed in as an argument or entered after a prompt.

```function FlippingBitsGame(n)
% Play the flipping bits game on an n x n array

% Generate random target array
fprintf('Welcome to the Flipping Bits Game!\n')
if nargin < 1
n = input('What dimension array should we use? ');
end
Tar = logical(randi([0 1], n));

% Generate starting array by randomly flipping rows or columns
Cur = Tar;
while all(Cur(:) == Tar(:))
nFlips = randi([3*n max(10*n, 100)]);
randDim = randi([0 1], nFlips, 1);
randIdx = randi([1 n], nFlips, 1);
for k = 1:nFlips
if randDim(k)
Cur(randIdx(k), :) = ~Cur(randIdx(k), :);
else
Cur(:, randIdx(k)) = ~Cur(:, randIdx(k));
end
end
end

% Print rules
fprintf('Given a %d x %d logical array,\n', n, n)
fprintf('and a target array configuration,\n')
fprintf('attempt to transform the array to the target\n')
fprintf('by inverting the bits in a whole row or column\n')
fprintf('at once in as few moves as possible.\n')
fprintf('Enter the corresponding letter to invert a column,\n')
fprintf('or the corresponding number to invert a row.\n')
fprintf('0 will reprint the target array, and no entry quits.\n\n')
fprintf('Target:\n')
PrintArray(Tar)

% Play until player wins or quits
move = true;
nMoves = 0;
while ~isempty(move) && any(Cur(:) ~= Tar(:))
fprintf('Move %d:\n', nMoves)
PrintArray(Cur)
move = lower(input('Enter move: ', 's'));
if length(move) > 1
fprintf('Invalid move, try again\n')
elseif move
r = str2double(move);
if isnan(r)
c = move-96;
if c > n || c < 1
fprintf('Invalid move, try again\n')
else
Cur(:, c) = ~Cur(:, c);
nMoves = nMoves+1;
end
else
if r > n || r < 0
fprintf('Invalid move, try again\n')
elseif r == 0
fprintf('Target:\n')
PrintArray(Tar)
else
Cur(r, :) = ~Cur(r, :);
nMoves = nMoves+1;
end
end
end
end

if all(Cur(:) == Tar(:))
fprintf('You win in %d moves! Try not to flip out!\n', nMoves)
else
fprintf('Quitting? The challenge a bit much for you?\n')
end
end

function PrintArray(A)
[nRows, nCols] = size(A);
fprintf('        ')
fprintf(' %c', (1:nCols)+96)
fprintf('\n')
for r = 1:nRows
fprintf('%8d%s\n', r, sprintf(' %d', A(r, :)))
end
fprintf('\n')
end
```
Output:

Normal play and winning:

```Welcome to the Flipping Bits Game!
What dimension array should we use? 3
Given a 3 x 3 logical array,
and a target array configuration,
attempt to transform the array to the target
by inverting the bits in a whole row or column
at once in as few moves as possible.
Enter the corresponding letter to invert a column,
or the corresponding number to invert a row.
0 will reprint the target array, and no entry quits.

Target:
a b c
1 0 0 0
2 0 1 0
3 0 0 0

Move 0:
a b c
1 1 1 1
2 1 0 1
3 1 1 1

Enter move: a
Move 1:
a b c
1 0 1 1
2 0 0 1
3 0 1 1

Enter move: b
Move 2:
a b c
1 0 0 1
2 0 1 1
3 0 0 1

Enter move: c
You win in 3 moves! Try not to flip out!```

Bad input, reprinting target, and quitting:

```Welcome to the Flipping Bits Game!
What dimension array should we use? 3
Given a 3 x 3 logical array,
and a target array configuration,
attempt to transform the array to the target
by inverting the bits in a whole row or column
at once in as few moves as possible.
Enter the corresponding letter to invert a column,
or the corresponding number to invert a row.
0 will reprint the target array, and no entry quits.

Target:
a b c
1 0 0 1
2 1 0 0
3 1 0 0

Move 0:
a b c
1 0 0 0
2 0 1 0
3 0 1 0

Enter move: a
Move 1:
a b c
1 1 0 0
2 1 1 0
3 1 1 0

Enter move: b
Move 2:
a b c
1 1 1 0
2 1 0 0
3 1 0 0

Enter move: 0
Target:
a b c
1 0 0 1
2 1 0 0
3 1 0 0

Move 2:
a b c
1 1 1 0
2 1 0 0
3 1 0 0

Enter move: hello
Invalid move, try again
Move 2:
a b c
1 1 1 0
2 1 0 0
3 1 0 0

Enter move: d
Invalid move, try again
Move 2:
a b c
1 1 1 0
2 1 0 0
3 1 0 0

Enter move: 4
Invalid move, try again
Move 2:
a b c
1 1 1 0
2 1 0 0
3 1 0 0

Enter move:
Quitting? The challenge a bit much for you?```

## MiniScript

```// Flipping Bits game.
// Transform a start grid to an end grid by flipping rows or columns.

size = 3

board = []
goal = []
for i in range(1,size)
row = []
for j in range(1,size)
row.push (rnd > 0.5)
end for
board.push row
goal.push row[0:]
end for

flipRow = function(n)
for j in range(0, size-1)
board[n-1][j] = not board[n-1][j]
end for
end function

flipCol = function(n)
for i in range(0, size-1)
board[i][n-1] = not board[i][n-1]
end for
end function

flipAny = function(s)
s = s[0].upper
if s >= "A" then flipCol s.code - 64 else flipRow val(s)
end function

for scramble in range(20)
if rnd < 0.5 then flipRow ceil(rnd*size) else flipCol ceil(rnd*size)
end for

solved = function()
for i in range(0, size-1)
for j in range(0, size-1)
if board[i][j] != goal[i][j] then return false
end for
end for
return true
end function

moveCount = 0
while true
print "  CURRENT:" + " "*(4+size*3) + "GOAL:"
for i in range(1,size)
s = i + " " + str(board[i-1])
s = s + " "*(3+size*3) + str(goal[i-1])
print s
end for
s = "   "
for i in range(1,size)
s = s + char(64+i) + "  "
end for
print s
if solved then break
moveCount = moveCount + 1
inp = input("Move " + moveCount + "? ")
flipAny(inp)
end while
print "You did it!"
```
Output:
```  CURRENT:             GOAL:
1 [0, 0, 0]            [0, 1, 1]
2 [1, 0, 1]            [1, 1, 0]
3 [1, 1, 0]            [0, 1, 0]
A  B  C
Move 1? 1
CURRENT:             GOAL:
1 [1, 1, 1]            [0, 1, 1]
2 [1, 0, 1]            [1, 1, 0]
3 [1, 1, 0]            [0, 1, 0]
A  B  C
Move 2? a
CURRENT:             GOAL:
1 [0, 1, 1]            [0, 1, 1]
2 [0, 0, 1]            [1, 1, 0]
3 [0, 1, 0]            [0, 1, 0]
A  B  C
Move 3? 2
CURRENT:             GOAL:
1 [0, 1, 1]            [0, 1, 1]
2 [1, 1, 0]            [1, 1, 0]
3 [0, 1, 0]            [0, 1, 0]
A  B  C
You did it!```

## Nim

Translation of: Kotlin

Translation of Kotlin program with some modifications.

```import random, strformat, strutils

type
Bit = range[0..1]
Board = array[3, array[3, Bit]]

#---------------------------------------------------------------------------------------------------

func flipRow(board: var Board; row: int) =
for cell in board[row].mitems:
cell = 1 - cell

#---------------------------------------------------------------------------------------------------

func flipCol(board: var Board; col: int) =
for row in board.mitems:
row[col] = 1 - row[col]

#---------------------------------------------------------------------------------------------------

proc initBoard(target: Board): Board =

# Starting from the target we make 9 random row or column flips.
result = target
for _ in 1..9:
if rand(1) == 0:
result.flipRow(rand(2))
else:
result.flipCol(rand(2))

#---------------------------------------------------------------------------------------------------

proc print(board: Board; label: string) =

echo &"{label}:"
echo "  | a b c"
echo "---------"
for r, row in board:
stdout.write &"{r + 1} |"
for cell in row: stdout.write &" {cell}"
echo ""
echo ""

#———————————————————————————————————————————————————————————————————————————————————————————————————

var target, board: Board

randomize()

# Initialize target.
for row in target.mitems:
for cell in row.mitems:
cell = rand(1)

# Initialize board and ensure it differs from the target i.e. game not already over!
while true:
board = initBoard(target)
if board != target:
break

target.print("TARGET")
board.print("OPENING BOARD")

var flips = 0
while board != target:

# Get input from player.
var isRow = true
var n = -1
while n < 0:
stdout.write "Enter row number or column letter to be flipped: "
stdout.flushFile()
let input = stdin.readLine()
let ch = if input.len > 0: input[0].toLowerAscii else: '0'
if ch notin "123abc":
echo "Must be 1, 2, 3, a, b or c"
continue
if ch in '1'..'3':
n = ord(ch) - ord('1')
else:
isRow = false
n = ord(ch) - ord('a')

# Update board.
inc flips
if isRow: board.flipRow(n) else: board.flipCol(n)
target.print("\nTARGET")
let plural = if flips == 1: "" else: "S"
board.print(&"BOARD AFTER {flips} FLIP{plural}")

let plural = if flips == 1: "" else: "s"
echo &"You’ve succeeded in {flips} flip{plural}"
```
Output:
```TARGET:
| a b c
---------
1 | 1 0 0
2 | 1 0 0
3 | 0 1 1

OPENING BOARD:
| a b c
---------
1 | 0 1 0
2 | 1 0 1
3 | 1 0 1

Enter row number or column letter to be flipped: a

TARGET:
| a b c
---------
1 | 1 0 0
2 | 1 0 0
3 | 0 1 1

BOARD AFTER 1 FLIP:
| a b c
---------
1 | 1 1 0
2 | 0 0 1
3 | 0 0 1

Enter row number or column letter to be flipped: 2

TARGET:
| a b c
---------
1 | 1 0 0
2 | 1 0 0
3 | 0 1 1

BOARD AFTER 2 FLIPS:
| a b c
---------
1 | 1 1 0
2 | 1 1 0
3 | 0 0 1

Enter row number or column letter to be flipped: b

TARGET:
| a b c
---------
1 | 1 0 0
2 | 1 0 0
3 | 0 1 1

BOARD AFTER 3 FLIPS:
| a b c
---------
1 | 1 0 0
2 | 1 0 0
3 | 0 1 1

You’ve succeeded in 3 flips
```

## OCaml

```module FlipGame =
struct
type t = bool array array

let make side = Array.make_matrix side side false

let flipcol b n =
for i = 0 to (Array.length b - 1) do
b.(n).(i) <- not b.(n).(i)
done

let fliprow b n =
for i = 0 to (Array.length b - 1) do
b.(i).(n) <- not b.(i).(n)
done

let randflip b =
let n = Random.int (Array.length b - 1) in
match Random.bool () with
| true -> fliprow b n
| false -> flipcol b n

let rec game side steps =
let start, target = make side, make side in
for i = 1 to steps do
randflip start;
randflip target
done;
if start = target then game side steps (* try again *) else
(start, target)

let print b =
for i = 0 to Array.length b - 1 do
for j = 0 to Array.length b - 1 do
Printf.printf " %d " (if b.(j).(i) then 1 else 0)
done;
print_newline ()
done;
print_newline ()

let draw_game board target =
print_endline "TARGET"; print target;
print_endline "BOARD"; print board
end

let play () =
let module G = FlipGame in
let board, target = G.game 3 10 in
let steps = ref 0 in
while board <> target do
G.draw_game board target;
print_string "> ";
flush stdout;
incr steps;
match String.split_on_char ' ' (read_line ()) with
| ["row"; row] ->
(match int_of_string_opt row with
| Some n -> G.fliprow board n
| None -> print_endline "(nothing happens)")
| ["col"; col] ->
(match int_of_string_opt col with
| Some n -> G.flipcol board n
| None -> print_endline "(nothing happens)")
| _ -> ()
done;
G.draw_game board target;
Printf.printf "\n\nGame solved in %d steps\n" !steps

let () =
if not !Sys.interactive then
(Random.self_init ();
play ())
```
Output:
```\$ ocamlc flipgame.ml -o flipgame
\$ ./flipgame
TARGET
0  0  1
0  0  1
1  1  0

BOARD
0  1  0
1  0  1
0  1  0

> col 1
TARGET
0  0  1
0  0  1
1  1  0

BOARD
0  0  0
1  1  1
0  0  0

> row 2
TARGET
0  0  1
0  0  1
1  1  0

BOARD
0  0  0
1  1  1
1  1  1

> col 2
TARGET
0  0  1
0  0  1
1  1  0

BOARD
0  0  1
1  1  0
1  1  0

> row 1
TARGET
0  0  1
0  0  1
1  1  0

BOARD
0  0  1
0  0  1
1  1  0

Game solved in 4 steps```

## Perl

Pass the size of the puzzle on the command line. It defaults to 4. You can play any size game between 2 and 26. While playing, the game accepts anything which looks like valid rows or columns, and disregards any irrelevant text in between.

```use strict;
use warnings qw(FATAL all);
use feature 'bitwise';

my \$n = shift(@ARGV) || 4;
if( \$n < 2 or \$n > 26 ) {
die "You can't play a size \$n game\n";
}

my \$n2 = \$n*\$n;

my (@rows, @cols);
for my \$i ( 0 .. \$n-1 ) {
my \$row = my \$col = "\x00" x \$n2;
vec(\$row, \$i * \$n + \$_, 8) ^= 1 for 0 .. \$n-1;
vec(\$col, \$i + \$_ * \$n, 8) ^= 1 for 0 .. \$n-1;
push @rows, \$row;
push @cols, \$col;
}

my \$goal = "0" x \$n2;
int(rand(2)) or (vec(\$goal, \$_, 8) ^= 1) for 0 .. \$n2-1;
my \$start = \$goal;
{
for(@rows, @cols) {
\$start ^.= \$_ if int rand 2;
}
redo if \$start eq \$goal;
}

my @letters = ('a'..'z')[0..\$n-1];
sub to_strings {
my \$board = shift;
my @result = join(" ", "  ", @letters);
for( 0 .. \$n-1 ) {
my \$res = sprintf("%2d ",\$_+1);
\$res .= join " ", split //, substr \$board, \$_*\$n, \$n;
push @result, \$res;
}
\@result;
}

my \$fmt;
my (\$stext, \$etext) = ("Starting board", "Ending board");
my \$re = join "|", reverse 1 .. \$n, @letters;
my \$moves_so_far = 0;
while( 1 ) {
my (\$from, \$to) = (to_strings(\$start), to_strings(\$goal));
unless( \$fmt ) {
my \$len = length \$from->[0];
\$len = length(\$stext) if \$len < length \$stext;
\$fmt = join(\$len, "%", "s%", "s\n");
}
printf \$fmt, \$stext, \$etext;
printf \$fmt, \$from->[\$_], \$to->[\$_] for 0 .. \$n;
last if \$start eq \$goal;
INPUT_LOOP: {
printf "Move #%s: Type one or more row numbers and/or column letters: ",
\$moves_so_far+1;
my \$input = <>;
die unless defined \$input;
my \$did_one;
for( \$input =~ /(\$re)/gi ) {
\$did_one = 1;
if( /\d/ ) {
\$start ^.= \$rows[\$_-1];
} else {
\$_ = ord(lc) - ord('a');
\$start ^.= \$cols[\$_];
}
++\$moves_so_far;
}
redo INPUT_LOOP unless \$did_one;
}
}
print "You won after \$moves_so_far moves.\n";
```
Output:
```\$ perl FlippingBitsGame.pl 3
Starting board  Ending board
a b c         a b c
1 0 0 1       1 1 1 1
2 0 1 1       2 1 0 1
3 0 0 0       3 0 0 1
Move #1: Type one or more row numbers and/or column letters: 12
Starting board  Ending board
a b c         a b c
1 1 1 0       1 1 1 1
2 1 0 0       2 1 0 1
3 0 0 0       3 0 0 1
Move #3: Type one or more row numbers and/or column letters: c
Starting board  Ending board
a b c         a b c
1 1 1 1       1 1 1 1
2 1 0 1       2 1 0 1
3 0 0 1       3 0 0 1
You won after 3 moves.```

The same game could have been won after typing 1 2 c in any order, with multiple lines or even "12c" on a single line.

## Phix

```integer w, h

string board, target

procedure new_board()
board = ""
h = prompt_number("Enter number of rows(1..9):",{1,9})
w = prompt_number("Enter number of columns(1..26):",{1,26})
string line = ""
for j=1 to w do line &= 'A'+j-1 end for
board = "  "&line&"\n"
for i=1 to h do
line = '0'+i&" "
for j=1 to w do line &= '0'+rand(2)-1 end for
board &= line&"\n"
end for
end procedure

procedure show_bt()
sequence sb = split(board,'\n'),
st = split(target,'\n')
printf(1,"board:%s     target:%s\n",{sb[1],st[1]})
for i=2 to length(sb)-1 do
printf(1,"      %s            %s\n",{sb[i],st[i]})
end for
end procedure

procedure flip(integer ch, bool bShow=true)
integer k
if ch>='A' and ch<='A'+w-1 then
-- flip_column
ch = ch-'A'+1
for i=1 to h do
k = 2+ch+i*(w+3)
board[k] = '0'+'1'-board[k]
end for
k = 2+ch
elsif ch>='1' and ch<='0'+h then
-- flip_row
ch -= '0'
for i=1 to w do
k = 2+i+(ch)*(w+3)
board[k] = '0'+'1'-board[k]
end for
k = 1+(ch)*(w+3)
else
?9/0    -- sanity check
end if
if bShow then
integer wasch = board[k]
board[k] = '*'
show_bt()
board[k] = wasch
end if
end procedure

procedure scramble_board()
integer lim = 10000
while 1 do
for i=1 to lim do
if rand(2)=1 then
flip('A'-1+rand(w),false)
else
flip('0'+rand(h),false)
end if
end for
if board!=target then exit end if
lim -= 1 -- sidestep the degenerate 1x1 case
end while
end procedure

function solve_board()
-- not guaranteed optimal (the commented-out length check clogs it on larger boards)
string original = board, moves
sequence next = {{0,board,""}},
legal_moves = tagset('A'+w-1,'A')&tagset('0'+h,'1')
atom t2 = time()+2 -- in case board is illegal/unsolveable
while time()<t2 do
for lm=1 to length(legal_moves) do
integer c = legal_moves[lm]
{?,board,moves} = next[1]
flip(c,false)
moves &= c
if board = target then
board = original
return moves
end if
next = append(next,{sum(sq_eq(board,target)),board,moves})
for i=length(next) to 3 by -1 do
if next[i][1]<=next[i-1][1] then exit end if
--              if length(next[i][3])>length(next[i-1][3]) then exit end if
{next[i-1],next[i]} = {next[i],next[i-1]}
end for
end for
next = next[2..\$]
end while
board = original
return 0
end function

constant ESC = #1B

procedure main()
integer moves = 0, solves = 0, ch
bool took_hint = false
new_board()
target = board
scramble_board()
show_bt()
object soln = solve_board()
while 1 do
string solve = iff(string(soln)?sprintf(" solveable in %d,",length(soln)):"")
printf(1,"moves taken %d,%s enter your move (A..%c or 1..%c) or ?:",{moves,solve,'A'+w-1,'0'+h})
while 1 do
ch = upper(wait_key())
if ch<=#FF then exit end if -- (ignore control keys)
end while
printf(1,"%c\n",ch)
if (ch>='A' and ch<='A'+w-1)
or (ch>='1' and ch<='0'+h) then
flip(ch)
if board=target then
printf(1,"\nWell %s!\n\n",{iff(took_hint?"cheated","done")})
exit
end if
moves += 1
soln = iff(string(soln) and ch=soln[1]?soln[2..\$]:solve_board())
elsif string(soln) and
(ch='H' -- (nb consumed above if w>=8)
or ch='.') then
took_hint = true
printf(1,"hint: %c\n",soln[1])
elsif ch='Q' -- (nb consumed above if w>=17)
or ch=ESC then
exit
elsif string(soln) and
(ch='S' -- (nb consumed above if w>=19)
or ch='!') then
for i=1 to length(soln) do
printf(1,"auto-solving, move %d:\n",i)
flip(soln[i])
sleep(2)
end for
exit
else
puts(1,"press ")
if string(soln) then
puts(1,"'!' (or 's' if width<19) to solve the board automatically,\n")
puts(1,"      '.' (or 'h' if width<8) to show hint,\n")
end if
puts(1,"      escape (or 'q' if width<17) to quit\n")
end if
end while
end procedure
main()
```
Output:
```Enter number of rows(1..9):2
Enter number of columns(1..26):2
board:  AB     target:  AB
1 11            1 10
2 00            2 10
moves taken 0, solveable in 2, enter your move (A..B or 1..2) or ?:?
press '!' (or 's' if width<19) to solve the board automatically,
'.' (or 'h' if width<8) to show hint,
escape (or 'q' if width<17) to quit
moves taken 0, solveable in 2, enter your move (A..B or 1..2) or ?:H
hint: A
moves taken 0, solveable in 2, enter your move (A..B or 1..2) or ?:A
board:  *B     target:  AB
1 01            1 10
2 10            2 10
moves taken 1, solveable in 1, enter your move (A..B or 1..2) or ?:H
hint: 1
moves taken 1, solveable in 1, enter your move (A..B or 1..2) or ?:1
board:  AB     target:  AB
* 10            1 10
2 10            2 10

Well cheated!
```

An auto solve:

```Enter number of rows(1..9):2
Enter number of columns(1..26):2
board:  AB     target:  AB
1 10            1 00
2 10            2 11
moves taken 0, solveable in 2, enter your move (A..B or 1..2) or ?:!
auto-solving, move 1:
board:  *B     target:  AB
1 00            1 00
2 00            2 11
auto-solving, move 2:
board:  AB     target:  AB
1 00            1 00
* 11            2 11
```

The maximum board size is 9x26:

```Enter number of rows(1..9):9
Enter number of columns(1..26):26
board:  ABCDEFGHIJKLMNOPQRSTUVWXYZ     target:  ABCDEFGHIJKLMNOPQRSTUVWXYZ
1 11010000101000110010101101            1 00010011000001110010101001
2 10000011010000110100001100            2 10111111000110001011110111
3 00100011010011100110111101            3 11100000111010100110111001
4 00101110001111100001001000            4 00010010011001011110110011
5 01001001111011101011100011            5 10001010010010101011100111
6 01010001101111101110111011            6 10010010000110101110111111
7 10011000011101100100000111            7 01011011110100100100000011
8 01111100111110000001100101            8 01000000101000111110011110
9 00111000101100111000011011            9 11111011000101111000011111
moves taken 0, solveable in 11, enter your move (A..Z or 1..9) or ?:
```

And the minimum is 1x1:

```Enter number of rows(1..9):1
Enter number of columns(1..26):1
board:  A     target:  A
1 0            1 1
moves taken 0, solveable in 1, enter your move (A..A or 1..1) or ?:1
board:  A     target:  A
* 1            1 1
Well done!
```

## PL/I

```(subscriptrange, stringrange, stringsize):
flip: procedure options (main);
declare n fixed binary;

put skip list ('This is the bit-flipping game.  What size of board do you want?');
get list (n);
put skip list
('Your task is to change your board so as match the board on the right (the objective)');

begin;
declare initial(n,n) bit (1), objective(n,n) bit (1);
declare (i, j, k, move) fixed binary;
declare ch character(1);
declare alphabet character (26) initial ('abcdefghijklmnopqrstuvwxyz');

on subrg
begin; put skip list ('Your row or column ' || trim(ch) || ' is out of range'); stop; end;

initial, objective = iand(random()*99, 1) = 1;

/* Set up the objective array: */
do i = 1 to n-1;
j = random()*n+1;  objective(j,*) = ^objective(j,*);
j = random()*n+1;  objective(*,j) = ^objective(*,j);
end;

do move = 0 by 1;
put skip edit ( center('You', n*3), center('The objective', 3*n+4) ) (x(3), a);
put skip edit ( (substr(alphabet, i, 1) do i = 1 to n) ) (x(5), (n) a(3));
put      edit ( (substr(alphabet, i, 1) do i = 1 to n) ) (x(3), (n) a(3));
do i = 1 to n;
put skip edit (i, initial(i,*), objective(i,*)) ((n+1) f(3), x(3), (n) F(3));
end;

if all(initial = objective) then leave;

put skip(2) list
('Please type a row number or column letter whose bits you want to flip: ');
get edit (ch) (L); put edit (ch) (a);
k = index(alphabet, ch);
if k > 0 then
initial(*, k) = ^initial(*,k); /* Flip column k */
else
initial(ch,*) = ^initial(ch,*); /* Flip row ch */
end;
put skip(2) list ('Congratulations. You solved it in ' || trim(move) || ' moves.');
end;

end flip;```
Output:
```This is the bit-flipping game.  What size of board do you want?

Your task is to change your board so as match the board on the right (the objective)
You      The objective
a  b  c     a  b  c
1  1  1  1     0  1  1
2  0  0  0     1  0  0
3  1  1  1     1  0  0

Please type a row number or column letter whose bits you want to flip:
3
You      The objective
a  b  c     a  b  c
1  1  1  1     0  1  1
2  0  0  0     1  0  0
3  0  0  0     1  0  0

Please type a row number or column letter whose bits you want to flip:
a
You      The objective
a  b  c     a  b  c
1  0  1  1     0  1  1
2  1  0  0     1  0  0
3  1  0  0     1  0  0

Congratulations. You solved it in 2 moves.
```

## Python

```"""
Given a %i by %i sqare array of zeroes or ones in an initial
configuration, and a target configuration of zeroes and ones
The task is to transform one to the other in as few moves as
possible by inverting whole numbered rows or whole lettered
columns at once.
In an inversion any 1 becomes 0 and any 0 becomes 1 for that
whole row or column.

"""

from random import randrange
from copy import deepcopy
from string import ascii_lowercase

try:    # 2to3 fix
input = raw_input
except:
pass

N = 3   # N x N Square arrray

board  = [[0]* N for i in range(N)]

def setbits(board, count=1):
for i in range(count):
board[randrange(N)][randrange(N)] ^= 1

def shuffle(board, count=1):
for i in range(count):
if randrange(0, 2):
fliprow(randrange(N))
else:
flipcol(randrange(N))

def pr(board, comment=''):
print(str(comment))
print('     ' + ' '.join(ascii_lowercase[i] for i in range(N)))
print('  ' + '\n  '.join(' '.join(['%2s' % j] + [str(i) for i in line])
for j, line in enumerate(board, 1)))

def init(board):
setbits(board, count=randrange(N)+1)
target = deepcopy(board)
while board == target:
shuffle(board, count=2 * N)
prompt = '  X, T, or 1-%i / %s-%s to flip: ' % (N, ascii_lowercase[0],
ascii_lowercase[N-1])
return target, prompt

def fliprow(i):
board[i-1][:] = [x ^ 1 for x in board[i-1] ]

def flipcol(i):
for row in board:
row[i] ^= 1

if __name__ == '__main__':
print(__doc__ % (N, N))
target, prompt = init(board)
pr(target, 'Target configuration is:')
print('')
turns = 0
while board != target:
turns += 1
pr(board, '%i:' % turns)
ans = input(prompt).strip()
if (len(ans) == 1
and ans in ascii_lowercase and ascii_lowercase.index(ans) < N):
flipcol(ascii_lowercase.index(ans))
elif ans and all(ch in '0123456789' for ch in ans) and 1 <= int(ans) <= N:
fliprow(int(ans))
elif ans == 'T':
pr(target, 'Target configuration is:')
turns -= 1
elif ans == 'X':
break
else:
print("  I don't understand %r... Try again. "
"(X to exit or T to show target)\n" % ans[:9])
turns -= 1
else:
print('\nWell done!\nBye.')
```
Output:
```Given a 3 by 3 sqare array of zeroes or ones in an initial
configuration, and a target configuration of zeroes and ones
The task is to transform one to the other in as few moves as
possible by inverting whole numbered rows or whole lettered
columns at once.
In an inversion any 1 becomes 0 and any 0 becomes 1 for that
whole row or column.

Target configuration is:
a b c
1 0 1 0
2 0 0 0
3 0 0 0

1:
a b c
1 1 0 0
2 0 0 1
3 0 0 1
X, T, or 1-3 / a-c to flip: 1
2:
a b c
1 0 1 1
2 0 0 1
3 0 0 1
X, T, or 1-3 / a-c to flip: c

Well done!
Bye.```
Showing bad/other inputs
```Target configuration is:
a b c
1 0 0 0
2 0 0 0
3 0 0 1

1:
a b c
1 1 0 1
2 0 1 0
3 0 1 1
X, T, or 1-3 / a-c to flip: 3
2:
a b c
1 1 0 1
2 0 1 0
3 1 0 0
X, T, or 1-3 / a-c to flip: 4
I don't understand '4'... Try again. (X to exit or T to show target)

2:
a b c
1 1 0 1
2 0 1 0
3 1 0 0
X, T, or 1-3 / a-c to flip: c
3:
a b c
1 1 0 0
2 0 1 1
3 1 0 1
X, T, or 1-3 / a-c to flip: d
I don't understand 'd'... Try again. (X to exit or T to show target)

3:
a b c
1 1 0 0
2 0 1 1
3 1 0 1
X, T, or 1-3 / a-c to flip: T
Target configuration is:
a b c
1 0 0 0
2 0 0 0
3 0 0 1
3:
a b c
1 1 0 0
2 0 1 1
3 1 0 1
X, T, or 1-3 / a-c to flip: X```

## QB64

```RANDOMIZE TIMER
DIM SHARED cellsPerSide, legalMoves\$, startB\$, currentB\$, targetB\$, moveCount

restart
DO
displayStatus
IF currentB\$ = targetB\$ THEN 'game done!
PRINT " Congratulations, done in"; moveCount; " moves."
PRINT "": PRINT " Press y for yes, if you want to start over > ";
yes\$ = getKey\$: PRINT yes\$: _DELAY .4: vcls
IF yes\$ = "y" THEN restart ELSE nomore = -1
ELSE 'get next move
m\$ = " ": PRINT
WHILE INSTR(legalMoves\$, m\$) = 0
PRINT " Press a lettered column or a numbered row to flip (or 0,q,?,!) > ";
m\$ = getKey\$: PRINT m\$: _DELAY .4
IF m\$ = "!" THEN
showSolution = -1: m\$ = " ": EXIT WHILE
ELSEIF m\$ = "?" THEN: m\$ = " ": cp CSRLIN, "Hint: " + hint\$
ELSEIF m\$ = "0" OR m\$ = "q" THEN: vcls: CLOSE: END
ELSEIF m\$ = "" THEN: m\$ = " "
END IF
WEND
IF showSolution THEN 'run the solution from hints function
showSolution = 0: mv\$ = hint\$
cp CSRLIN + 1, "For the next move, the AI has chosen: " + mv\$
cp CSRLIN + 1, "Running the solution with 4 sec screen delays..."
_DELAY 4: vcls
WHILE mv\$ <> "Done?"
moveCount = moveCount + 1: makeMove mv\$: displayStatus: mv\$ = hint\$
cp CSRLIN + 1, "For the next move, the AI has chosen: " + mv\$
cp CSRLIN + 1, "Running the solution with 4 sec screen delays..."
_DELAY 4: vcls
WEND
displayStatus
cp CSRLIN + 1, "Done! Current board matches Target"
cp CSRLIN + 1, "Press y for yes, if you want to start over: > "
yes\$ = getKey\$: PRINT yes\$: _DELAY .4: vcls
IF yes\$ = "y" THEN restart ELSE nomore = -1
ELSE
vcls: moveCount = moveCount + 1: makeMove m\$
END IF
END IF
LOOP UNTIL nomore
CLOSE

SUB displayStatus
COLOR 9: showBoard 2, 2, currentB\$, "Current:"
COLOR 12: showBoard 2, 2 + 2 * cellsPerSide + 6, targetB\$, "Target:"
COLOR 13: PRINT: PRINT " Number of moves taken so far is" + STR\$(moveCount)
COLOR 14
END SUB

FUNCTION hint\$ 'compare the currentB to targetB and suggest letter or digit or done
FOR i = 1 TO 2 * cellsPerSide 'check cols first then rows as listed in legalMoves\$
r\$ = MID\$(legalMoves\$, i, 1)
IF i <= cellsPerSide THEN
currentbit\$ = MID\$(currentB\$, i, 1): targetBit\$ = MID\$(targetB\$, i, 1)
IF currentbit\$ <> targetBit\$ THEN flag = -1: EXIT FOR
ELSE
j = i - cellsPerSide
currentbit\$ = MID\$(currentB\$, (j - 1) * cellsPerSide + 1, 1)
targetBit\$ = MID\$(targetB\$, (j - 1) * cellsPerSide + 1, 1)
IF currentbit\$ <> targetBit\$ THEN flag = -1: EXIT FOR
END IF
NEXT
IF flag THEN hint\$ = r\$ ELSE hint\$ = "Done?"
END FUNCTION

SUB restart
CLOSE
OPEN "Copy Flipping Bits Game.txt" FOR OUTPUT AS #3
cellsPerSide = 0: legalMoves\$ = "": moveCount = 0
COLOR 9: cp 3, "Flipping Bits Game, now with AI!  b+ 2017-12-18"
COLOR 5
cp 5, "You will be presented with a square board marked Current and"
cp 6, "another marked Target. The object of the game is to match"
cp 7, "the Current board to Target in the least amount of moves."
cp 9, "To make a move, enter a letter for a column to flip or"
cp 10, "a digit for a row to flip. In a flip, all 1's are"
cp 11, "changed to 0's and all 0's changed to 1's."
cp 13, "You may enter 0 or q at any time to quit."
cp 14, "You may press ? when prompted for move to get a hint."
cp 15, "You may press ! to have the program solve the puzzle."
COLOR 14: PRINT: PRINT
WHILE cellsPerSide < 2 OR cellsPerSide > 9
LOCATE CSRLIN, 13: PRINT "Please press how many cells you want per side 2 to 9 > ";
in\$ = getKey\$: PRINT in\$: _DELAY .4
IF in\$ = "0" OR in\$ = "q" THEN END ELSE cellsPerSide = VAL(in\$)
WEND
vcls
FOR i = 1 TO cellsPerSide: legalMoves\$ = legalMoves\$ + CHR\$(96 + i): NEXT
FOR i = 1 TO cellsPerSide: legalMoves\$ = legalMoves\$ + LTRIM\$(STR\$(i)): NEXT
startB\$ = startBoard\$: currentB\$ = startB\$: targetB\$ = makeTarget\$: currentB\$ = startB\$
END SUB

FUNCTION startBoard\$
FOR i = 1 TO cellsPerSide ^ 2: r\$ = r\$ + LTRIM\$(STR\$(INT(RND * 2))): NEXT
startBoard\$ = r\$
END FUNCTION

SUB showBoard (row, col, board\$, title\$)
LOCATE row - 1, col: PRINT title\$
FOR i = 1 TO cellsPerSide
LOCATE row, col + 2 * (i - 1) + 3: PRINT MID\$(legalMoves\$, i, 1);
NEXT
PRINT
FOR i = 1 TO cellsPerSide
LOCATE row + i, col - 1: PRINT STR\$(i);
FOR j = 1 TO cellsPerSide
LOCATE row + i, col + 2 * j: PRINT " " + MID\$(board\$, (i - 1) * cellsPerSide + j, 1);
NEXT
PRINT
NEXT
END SUB

SUB makeMove (move\$)
ac = ASC(move\$)
IF ac > 96 THEN 'letter
col = ac - 96
FOR i = 1 TO cellsPerSide
bit\$ = MID\$(currentB\$, (i - 1) * cellsPerSide + col, 1)
IF bit\$ = "0" THEN
MID\$(currentB\$, (i - 1) * cellsPerSide + col, 1) = "1"
ELSE
MID\$(currentB\$, (i - 1) * cellsPerSide + col, 1) = "0"
END IF
NEXT
ELSE 'number
row = ac - 48
FOR i = 1 TO cellsPerSide
bit\$ = MID\$(currentB\$, (row - 1) * cellsPerSide + i, 1)
IF bit\$ = "0" THEN
MID\$(currentB\$, (row - 1) * cellsPerSide + i, 1) = "1"
ELSE
MID\$(currentB\$, (row - 1) * cellsPerSide + i, 1) = "0"
END IF
NEXT
END IF
END SUB

FUNCTION makeTarget\$
WHILE currentB\$ = startB\$
FOR i = 1 TO cellsPerSide * cellsPerSide
m\$ = MID\$(legalMoves\$, INT(RND * LEN(legalMoves\$)) + 1, 1): makeMove m\$
NEXT
WEND
makeTarget\$ = currentB\$
END FUNCTION

SUB cp (row, text\$) 'center print at row
LOCATE row, (80 - LEN(text\$)) / 2: PRINT text\$;
END SUB

SUB vcls 'print the screen to file then clear it
DIM s\$(23)
FOR lines = 1 TO 23
FOR t = 1 TO 80: scan\$ = scan\$ + CHR\$(SCREEN(lines, t)): NEXT
s\$(lines) = RTRIM\$(scan\$): scan\$ = ""
NEXT
FOR fini = 23 TO 1 STEP -1
IF s\$(fini) <> "" THEN EXIT FOR
NEXT
PRINT #3, ""
FOR i = 1 TO fini: PRINT #3, s\$(i): NEXT
PRINT #3, "": PRINT #3, STRING\$(80, "-"): CLS
END SUB

FUNCTION getKey\$ 'just want printable characters
k\$ = ""
WHILE LEN(k\$) = 0
k\$ = INKEY\$
IF LEN(k\$) THEN 'press something so respond
IF LEN(k\$) = 2 OR ASC(k\$) > 126 OR ASC(k\$) < 32 THEN k\$ = "*": BEEP
END IF
WEND
getKey\$ = k\$
END FUNCTION
```

Output:

```Flipping Bits Game, now with AI!  b+ 2017-12-18

You will be presented with a square board marked Current and
another marked Target. The object of the game is to match
the Current board to Target in the least amount of moves.

To make a move, enter a letter for a column to flip or
a digit for a row to flip. In a flip, all 1's are
changed to 0's and all 0's changed to 1's.

You may enter 0 or q at any time to quit.
You may press ? when prompted for move to get a hint.
You may press ! to have the program solve the puzzle.

Please press how many cells you want per side 2 to 9 > l
Please press how many cells you want per side 2 to 9 > *
Please press how many cells you want per side 2 to 9 > 3

--------------------------------------------------------------------------------

Current:    Target:
a b c       a b c
1  1 1 0    1  0 1 1
2  1 1 0    2  0 1 1
3  0 0 1    3  0 1 1

Number of moves taken so far is 0

Press a lettered column or a numbered row to flip (or 0,q,?,!) > l
Press a lettered column or a numbered row to flip (or 0,q,?,!) > 9
Press a lettered column or a numbered row to flip (or 0,q,?,!) > *
Press a lettered column or a numbered row to flip (or 0,q,?,!) > a

--------------------------------------------------------------------------------

Current:    Target:
a b c       a b c
1  0 1 0    1  0 1 1
2  0 1 0    2  0 1 1
3  1 0 1    3  0 1 1

Number of moves taken so far is 1

Press a lettered column or a numbered row to flip (or 0,q,?,!) > ?
Hint: c
Press a lettered column or a numbered row to flip (or 0,q,?,!) > c

--------------------------------------------------------------------------------

Current:    Target:
a b c       a b c
1  0 1 1    1  0 1 1
2  0 1 1    2  0 1 1
3  1 0 0    3  0 1 1

Number of moves taken so far is 2

Press a lettered column or a numbered row to flip (or 0,q,?,!) > l
Press a lettered column or a numbered row to flip (or 0,q,?,!) > 9
Press a lettered column or a numbered row to flip (or 0,q,?,!) > !

For the next move, the AI has chosen: 3
Running the solution with 4 sec screen delays...

--------------------------------------------------------------------------------

Current:    Target:
a b c       a b c
1  0 1 1    1  0 1 1
2  0 1 1    2  0 1 1
3  0 1 1    3  0 1 1

Number of moves taken so far is 3

For the next move, the AI has chosen: Done?
Running the solution with 4 sec screen delays...

--------------------------------------------------------------------------------

Current:    Target:
a b c       a b c
1  0 1 1    1  0 1 1
2  0 1 1    2  0 1 1
3  0 1 1    3  0 1 1

Number of moves taken so far is 3

Done! Current board matches Target
Press y for yes, if you want to start over: > m

--------------------------------------------------------------------------------
```

## Quackery

`transpose` is defined at Matrix transposition#Quackery.

```  [ [] over times
[ over [] swap times
[ 2 random join ]
nested join ]
nip ]                             is makeboard   (   n --> [   )

[ [] swap witheach [ not join ] ]   is invert      (   [ --> [   )

[ 2dup peek invert unrot poke ]     is fliprow     ( [ n --> [   )

[ dip transpose fliprow transpose ] is flipcolumn  ( [ n --> [   )

[ dup
[ dup size dup * times
[ dup size random
2 random iff
fliprow
else flipcolumn ]
2dup != until ]
nip ]                             is mix         (   [ --> [   )

[ say "   "
dup size times
[ sp i^ char a + emit ]
witheach
[ cr sp i^ echo say ":"
witheach
[ sp echo ] ] ]             is display     (   [ -->     )

[ cr \$ "a..., or 0...: "
input \$ "." join
trim 0 peek lower
2dup char a rot over +
within iff
[ nip char a -
' flipcolumn ]
done
2dup char 0 rot over +
within iff
[ nip char 0 -
' fliprow ]
done
drop again ]                     is getmove     (   n --> n x )

[ 0 temp put
makeboard
dup mix
[ say "Moves: "
temp share echo cr
1 temp tally
2dup swap
say "Target" cr
display cr cr
say "Current" cr
display cr
dup size getmove do cr
2dup = until ]
2drop
temp take
say "Moves taken: " echo ]        is flipbits    (   n -->     )```
Output:

As a dialogue in the Quackery shell (REPL).

```/O>/O> 3 flipbits
...
Moves: 0
Target
a b c
0: 1 0 0
1: 0 0 1
2: 0 1 0

Current
a b c
0: 1 0 1
1: 1 1 1
2: 1 0 0

a..., or 0...: a

Moves: 1
Target
a b c
0: 1 0 0
1: 0 0 1
2: 0 1 0

Current
a b c
0: 0 0 1
1: 0 1 1
2: 0 0 0

a..., or 0...: 1

Moves: 2
Target
a b c
0: 1 0 0
1: 0 0 1
2: 0 1 0

Current
a b c
0: 0 0 1
1: 1 0 0
2: 0 0 0

a..., or 0...: 0

Moves: 3
Target
a b c
0: 1 0 0
1: 0 0 1
2: 0 1 0

Current
a b c
0: 1 1 0
1: 1 0 0
2: 0 0 0

a..., or 0...: b

Moves: 4
Target
a b c
0: 1 0 0
1: 0 0 1
2: 0 1 0

Current
a b c
0: 1 0 0
1: 1 1 0
2: 0 1 0

a..., or 0...: 1

Moves taken: 5
Stack empty.

/O> ```

## Racket

```#lang racket
(define (flip-row! pzzl r)
(define N (integer-sqrt (bytes-length pzzl)))
(for* ((c (in-range N)))
(define idx (+ c (* N r)))
(bytes-set! pzzl idx (- 1 (bytes-ref pzzl idx)))))

(define (flip-col! pzzl c)
(define N (integer-sqrt (bytes-length pzzl)))
(for* ((r (in-range N)))
(define idx (+ c (* N r)))
(bytes-set! pzzl idx (- 1 (bytes-ref pzzl idx)))))

(define (new-game N (flips 10))
(define N2 (sqr N))
(define targ (list->bytes (for/list ((_ N2)) (random 2))))
(define strt (bytes-copy targ))
(for ((_ flips))
(case (random 2)
((0) (flip-col! strt (random N)))
((1) (flip-row! strt (random N)))))
(if (equal? strt targ) (new-game N) (values targ strt)))

(define (show-games #:sep (pzl-sep " | ") . pzzls)
(define N (integer-sqrt (bytes-length (first pzzls))))
(define caption (string-join (for/list ((c (in-range N))) (~a (add1 c))) ""))
(define ruler   (string-join (for/list ((c (in-range N))) "-") ""))

(define ((pzzle-row r) p)
(string-join (for/list ((c (in-range N))) (~a (bytes-ref p (+ c (* N r))))) ""))

(displayln
(string-join
(list*
(format "  ~a" (string-join (for/list ((_ pzzls)) caption) pzl-sep))
(format "  ~a" (string-join (for/list ((_ pzzls)) ruler) pzl-sep))
(for/list ((r (in-range N)) (R (in-naturals (char->integer #\a))))
(format "~a ~a" (integer->char R) (string-join (map (pzzle-row r) pzzls) pzl-sep))))
"\n")))

(define (play N)
(define-values (end start) (new-game N))
(define (turn n (show? #t))
(cond
[(equal? end start) (printf "you won on turn #~a~%" n)]
[else
(when show? ;; don't show after whitespace
(printf "turn #~a~%" n)
(show-games start end))
(match (read-char)
[(? eof-object?) (printf "sad to see you go :-(~%")]
[(? char-whitespace?) (turn n #f)]
[(? char-numeric? c)
(define cnum (- (char->integer c) (char->integer #\1)))
(cond [(< -1 cnum N)
(printf "flipping col ~a~%" (add1 cnum))
(flip-col! start cnum)
(turn (add1 n))]
[else (printf "column number out of range ~a > ~a~%" (add1 cnum) N)
(turn n)])]
[(? char-lower-case? c)
(define rnum (- (char->integer c) (char->integer #\a)))
(cond [(< -1 rnum N)
(printf "flipping row ~a~%" (add1 rnum))
(flip-row! start rnum)
(turn (add1 n))]
[else (printf "row number out of range ~a > ~a~%" (add1 rnum) (sub1 N))
(turn n)])]
[else (printf "unrecognised character in input: ~s~%" else)
(turn n)])]))
(turn 0))
```
Output:
```(play 3)
turn #0
123 | 123
--- | ---
a 001 | 101
b 110 | 101
c 100 | 000
1
flipping col 1
turn #1
123 | 123
--- | ---
a 101 | 101
b 010 | 101
c 000 | 000
b
flipping row 2
you won on turn #2```

## Raku

(formerly Perl 6)

Works with: rakudo version 2016.11

Pass in a parameter to set the square size for the puzzle. (Defaults to 4.) Arbitrarily limited to between 1 and 26. Yes, you can choose to solve a 1 element square puzzle, but it won't be very challenging. Accepts upper or lower case letters for columns. Disregards any out-of-range indices. Enter a blank or 0 (zero) to exit.

```sub MAIN (\$square = 4) {
say "{\$square}? Seriously?" and exit if \$square < 1 or \$square > 26;
my %bits = map { \$_ => %( map { \$_ => 0 }, ('A' .. *)[^ \$square] ) },
(1 .. *)[^ \$square];
scramble %bits;
my \$target = build %bits;
scramble %bits until build(%bits) ne \$target;
display(\$target, %bits);
my \$turns = 0;
while my \$flip = prompt "Turn {++\$turns}: Flip which row / column? " {
flip \$flip.match(/\w/).uc, %bits;
if display(\$target, %bits) {
say "Hurray! You solved it in \$turns turns.";
last;
}
}
}

sub display(\$goal, %hash) {
shell('clear');
say "Goal\n\$goal\nYou";
my \$this = build %hash;
say \$this;
return (\$goal eq \$this);
}

sub flip (\$a, %hash) {
given \$a {
when any(keys %hash) {
%hash{\$a}{\$_} = %hash{\$a}{\$_} +^ 1 for %hash{\$a}.keys
};
when any(keys %hash{'1'}) {
%hash{\$_}{\$a} = %hash{\$_}{\$a} +^ 1 for %hash.keys
};
}
}

sub build (%hash) {
my \$string = '   ';
\$string ~= sprintf "%2s ", \$_ for sort keys %hash{'1'};
\$string ~= "\n";
for %hash.keys.sort: +* -> \$key {
\$string ~= sprintf "%2s ", \$key;
\$string ~= sprintf "%2s ", %hash{\$key}{\$_} for sort keys %hash{\$key};
\$string ~=  "\n";
};
\$string
}

sub scramble(%hash) {
my @keys = keys %hash;
@keys.push: | keys %hash{'1'};
flip \$_,  %hash for @keys.pick( @keys/2 );
}
```

A sample 3 x 3 game might look like this:

```Goal
A  B  C
1  1  1  0
2  0  0  1
3  1  1  0

You
A  B  C
1  0  0  0
2  1  1  1
3  1  1  1

Turn 1: Flip which row / column? 2

Goal
A  B  C
1  1  1  0
2  0  0  1
3  1  1  0

You
A  B  C
1  0  0  0
2  0  0  0
3  1  1  1

Turn 2: Flip which row / column? 1

Goal
A  B  C
1  1  1  0
2  0  0  1
3  1  1  0

You
A  B  C
1  1  1  1
2  0  0  0
3  1  1  1

Turn 3: Flip which row / column? c

Goal
A  B  C
1  1  1  0
2  0  0  1
3  1  1  0

You
A  B  C
1  1  1  0
2  0  0  1
3  1  1  0

Hurray! You solved it in 3 turns.```

## Red

```Red []
random/seed   now/time/precise                 ;; start random generator
kRows: kCols: 3                                ;; define board size, 3x3 upto 9x9 possible
;; create series of 3 empty blocks:
loop kRows [ append/only board: []  copy [] ]  ;; ( this is actually a bit tricky, normally you'd have to use "copy" [] inside a loop )

kValid: "1A"                                    ;; generate string for input validation "321ABC"
loop (kRows - 1 ) [insert kValid (first kValid) + 1 ]
loop (kCols - 1 ) [append kValid (last kValid) + 1 ]

repeat row kRows [ loop kCols [ append board/:row -1 + random 2 ] ] ;; fill board with random 0 / 1
;;--------------------------------------
xorme: func ['val][ set val 1 xor get val ]           ;; function: flip the given board position
;;--------------------------------------
flip: func [ what [string!] ] [                       ;; flip complete row or column  of board
row:  -48 + to-integer first  what                   ;; convert string to integer row/column index
if row <= kRows  [ repeat col kCols [ xorme board/:row/:col] return 0 ]
repeat row2 kRows [ xorme board/:row2/(row - 16)]
]
;;--------------------------------------
showboard: func [title [string!] b] [                           ;; function: show board name + board or target
prin [title newline newline" " letter: #"A" ]                 ;; ( prin doesn't print newline at end )
loop ( kCols - 1) [ prin ["" letter: letter + 1] ] print ""   ;; print column letters
repeat row kRows [                                            ;; print one row
prin row                                                    ;; first print row number
repeat col kCols [ prin ["" b/:row/:col ]]
print ""
]
]

showboard "Target" target: copy/deep board               ;; create target as copy from board and show
random kvalid
repeat pos 3 [flip copy/part skip kvalid pos 1]          ;; now flip board 3 times at random row/column

run: -1
forever [
showboard "Board" board
if board = target [ Print ["You solved it in" run + 1 "move(s) !" ] halt ]          ;; count last move
print [newline "moves:" run: run + 1   ]                                            ;; show moves taken so far
until [ find kvalid inp: uppercase ask "Enter Row No or Column Letter to flip ?" ]  ;; read valid input character
flip  inp
]                                                         ;; 42 lines :- )
```
Output:
```Target
A B C
1 0 1 0
2 1 1 0
3 1 1 0

Board
A B C
1 1 1 0
2 1 0 1
3 1 0 1

moves: 0
Enter Row No or Column Letter to flip ?1

Board
A B C
1 0 0 1
2 1 0 1
3 1 0 1

moves: 1
Enter Row No or Column Letter to flip ?C

Board
A B C
1 0 0 0
2 1 0 0
3 1 0 0

moves: 2
Enter Row No or Column Letter to flip ?B

Board
A B C
1 0 1 0
2 1 1 0
3 1 1 0
You solved it in 3 move(s) !
(halted)
```

## REXX

This REXX version allows the specification (on the invocation line) for:

•   the size of the array (grid)   [the default is 3,   the maximum is 26]
•   the number of bits (for the target) to be flipped is the size of the grid   (the whole row or column)

Programming note:   none of the command line parameters   (N   and   u)   are checked for errors (so as to make the
program simpler).   A fair amount of coding was added to check for a legal "move".

```/*REXX program presents a  "flipping bit"  puzzle.  The user can solve via it via  C.L. */
parse arg  N u seed .                            /*get optional arguments from the C.L. */
if N==''  |  N==","     then N=3                 /*Size given?   Then use default of  3.*/
if u==''  |  u==","     then u=N                 /*the number of bits initialized to ON.*/
if datatype(seed, 'W')  then call random ,,seed  /*is there a seed (for repeatability?) */
col@= 'a b c d e f g h i j k l m n o p q r s t u v w x y z'     /*literal for column id.*/
cols=space(col@, 0);        upper cols           /*letters to be used for the columns.  */
@.=0;  !.=0                                      /*set both arrays to  "off" characters.*/
tries=0                                          /*number of player's attempts (so far).*/
do  while  show(0) < u                  /* [↓]   turn  "on"  U  number of bits.*/
r=random(1, N);      c=random(1, N)     /*get a random  row  and  column.      */
@.r.c=1       ;      !.r.c=1            /*set (both)  row and column  to ON.   */
end   /*while*/                         /* [↑]  keep going 'til   U   bits set.*/
oz=z                                             /*save the original array string.      */
call show 1, '   ◄═══target═══╣', , 1            /*display the target for user to attain*/
do random(1,2); call flip 'R',random(1,N) /*flip a   row    of  bits.            */
call flip 'C',random(1,N) /*  "  "  column   "    "              */
end   /*random*/                          /* [↑]  just perform  1  or  2  times. */
if z==oz  then call flip 'R', random(1, N)       /*ensure it's not target we're flipping*/
do  until  z==oz;      call prompt        /*prompt until they get it right.      */
call flip left(?, 1),  substr(?, 2)       /*flip a user selected row or column.  */
call show 0                               /*get image (Z) of the updated array.  */
end   /*until*/
call show 1, '   ◄───your array'                 /*display the array to the terminal.   */
say '─────────Congrats!    You did it in'     tries     "tries."
exit tries                                       /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
halt:  say 'program was halted by user.';  exit  /*the REXX program was halted by user. */
hdr:   aaa=arg(1);  if oo==1  then aaa=translate(aaa, "╔═║", '┌─│');    say aaa;    return
isInt: return datatype( arg(1), 'W')             /*returns   1   if  arg  is an integer.*/
isLet: return datatype( arg(1), 'M')             /*returns   1   if  arg  is a letter.  */
terr:  if ok  then say  '───────── ***error***:  illegal'  arg(1);        ok=0;     return
/*──────────────────────────────────────────────────────────────────────────────────────*/
flip: arg x,#;   do c=1  for N  while x=='R';  @.#.c = \@.#.c;  end  /*c*/
do r=1  for N  while x=='C';  @.r.# = \@.r.#;  end  /*r*/;         return
/*──────────────────────────────────────────────────────────────────────────────────────*/
prompt: if tries\==0  then  say '─────────bit array after play: '         tries
signal on halt                           /*another method for the player to quit*/
!='─────────Please enter a    row number    or a    column letter,      or  Quit:'
call show 1, '   ◄───your array'         /*display the array to the terminal.   */
do forever  until ok;       ok=1;     say;     say !;     pull ?  _  .  1  aa
if abbrev('QUIT', ?, 1)     then do;  say '─────────quitting···';  exit 0;  end
if ?==''                    then do;  call show 1,"   ◄═══target═══╣",.,1; ok=0
call show 1,"   ◄───your array"
end                       /* [↑] reshow targ*/
if _ \== ''                 then call terr 'too many args entered:'   aa
if \isInt(?) & \isLet(?)    then call terr 'row/column: '             ?
if  isLet(?)                then a=pos(?, cols)
if  isLet(?) & (a<1 | a>N | length(?)>1)  then call terr 'column: '   ?
if  isLet(?)                then ?='C'pos(?, cols)
if  isInt(?) & (?<1 | ?>N)  then call terr 'row: '                    ?
if  isInt(?)                then ?='R' || (?/1)            /*normalize number*/
end   /*forever*/                                          /*end of da checks*/
tries= tries + 1                                              /*bump da counter.*/
return ?                                                      /*return response.*/
/*──────────────────────────────────────────────────────────────────────────────────────*/
show: \$=0;              _=;            parse arg tell,tx,o,oo         /*\$≡num of ON bits*/
if tell  then do; say;     say '     '   subword(col@, 1, N)   "  column letter"
call hdr 'row ┌'copies('─', N+N+1)            /*prepend col hdrs*/
end                                               /* [↑]  grid hdrs.*/
z=                                                              /* [↓] build grid.*/
do   r=1  for N                                               /*show  grid rows.*/
do c=1  for N;  if o==.  then do;  z=z || !.r.c;  _=_ !.r.c;  \$=\$ + !.r.c;   end
else do;  z=z || @.r.c;  _=_ @.r.c;  \$=\$ + @.r.c;   end
end   /*c*/                                                 /*··· and sum ONs.*/
if tx\==''  then tar.r=_ tx                                   /*build da target?*/
if tell     then call hdr right(r, 2)   ' │'_   tx; _=        /*show the grid?  */
end     /*r*/                                                 /*show a grid row.*/
if tell  then say;                     return \$                 /*show blank line?*/
```
output   when using the default input of:     3

Note that the user's input is also shown   (annotated).

Also note that the 2nd answer was a blank (or nothing), which caused the program to re-show the target array.

```      a b c   column letter
row ╔═══════
1  ║ 0 1 0    ◄═══target═══╣
2  ║ 0 0 0    ◄═══target═══╣
3  ║ 0 1 1    ◄═══target═══╣

a b c   column letter
row ┌───────
1  │ 1 0 0    ◄───your array
2  │ 1 1 0    ◄───your array
3  │ 0 1 0    ◄───your array

─────────Please enter a    row number    or a    column letter,      or  Quit:
b                                    ◄■■■■■■■■■■■■■ user input
─────────bit array after play:  1

a b c   column letter
row ┌───────
1  │ 1 1 0    ◄───your array
2  │ 1 0 0    ◄───your array
3  │ 0 0 0    ◄───your array

─────────Please enter a    row number    or a    column letter,      or  Quit:
a                                    ◄■■■■■■■■■■■■■ user input

─────────bit array after play:  2

a b c   column letter
row ┌───────
1  │ 0 1 0    ◄───your array
2  │ 0 0 0    ◄───your array
3  │ 1 0 0    ◄───your array

─────────Please enter a    row number    or a    column letter,      or  Quit:
3                                    ◄■■■■■■■■■■■■■ user input

a b c   column letter
row ┌───────
1  │ 0 1 0    ◄───your array
2  │ 0 0 0    ◄───your array
3  │ 0 1 1    ◄───your array

─────────Congrats!    You did it in 3 tries.
```
output   when using the following was used for input:     5
```      a b c d e   column letter
row ╔═══════════
1  ║ 1 0 0 0 0    ◄═══target═══╣
2  ║ 1 0 0 0 0    ◄═══target═══╣
3  ║ 1 0 0 0 0    ◄═══target═══╣
4  ║ 0 0 0 0 0    ◄═══target═══╣
5  ║ 0 0 1 1 0    ◄═══target═══╣

a b c d e   column letter
row ┌───────────
1  │ 0 0 1 1 0    ◄───your array
2  │ 1 1 0 0 1    ◄───your array
3  │ 1 1 0 0 1    ◄───your array
4  │ 0 1 0 0 1    ◄───your array
5  │ 0 1 1 1 1    ◄───your array

─────────Please enter a    row number    or a    column letter,      or  Quit:
q
─────────quitting···
```

## Ring

```load "guilib.ring"
load "stdlib.ring"

size = 3
flip = newlist(size,size)
board = newlist(size,size)
colflip = list(size)
rowflip = list(size)

new qapp
{
win1 = new qwidget() {
setwindowtitle("Flipping bits game")
setgeometry(465,115,800,600)
label1 = new qlabel(win1) {
setgeometry(285,60,120,40)
settext("Target")
}
label2 = new qlabel(win1) {
setgeometry(285,220,120,40)
settext("Board")
}
for n = 1 to size
for m = 1 to size
flip[n][m] = new qpushbutton(win1) {
setgeometry(200+n*40,60+m*40,40,40)
settext(string(random(1)))
}
next
next
for n = 1 to size
for m = 1 to size
board[n][m] = new qpushbutton(win1) {
setgeometry(200+n*40,260+m*40,40,40)
setclickevent("draw(" + n + "," + m +")")
}
next
next
for n = 1 to size
colflip[n]= new qpushbutton(win1) {
setgeometry(200+n*40,260,40,40)
settext("Go")
setclickevent("coldraw(" + n + ")")
}
next
for n = 1 to size
rowflip[n]= new qpushbutton(win1) {
setgeometry(200,260+n*40,40,40)
settext("Go")
setclickevent("rowdraw(" + n + ")")
}
next
scramblebutton = new qpushbutton(win1) {
setgeometry(240,460,120,40)
settext("Scramble Board")
setclickevent("scramble(flip)")
}
scramblebegin(flip)
show()
}
exec()
}

func coldraw(n)
for row = 1 to size
board[n][row] {temp = text()}
if temp = "0"
board[n][row].settext("1")
else
board[n][row].settext("0")
ok
next

func rowdraw(n)
for col = 1 to size
board[col][n] {temp = text()}
if temp = "0"
board[col][n].settext("1")
else
board[col][n].settext("0")
ok
next

func scramble(flip)
for col = 1 to size
for row = 1 to size
flip[col][row]{temp = text()}
board[col][row].settext(temp)
next
next
for mix = 1 to size*10
colorrow = random(1) + 1
colrow = random(size-1) + 1
if colorrow = 1
rc = "coldraw"
else
rc = "rowdraw"
ok
go = rc + "(" + colrow + ")"
eval(go)
next

func scramblebegin(flip)
for col = 1 to size
for row = 1 to size
flip[col][row]{temp = text()}
board[col][row].settext(temp)
next
next```

Output:

## Ruby

```class FlipBoard
def initialize(size)
raise ArgumentError.new("Invalid board size: #{size}") if size < 2

@size = size
@board = Array.new(size**2, 0)

randomize_board
loop do
@target = generate_target
break unless solved?
end

# these are used for validating user input
@columns = [*'a'...('a'.ord+@size).chr]
@rows = (1..@size).map(&:to_s)
end

############################################################

def play
moves = 0
puts "your target:", target

until solved?
puts "", "move #{moves}:", self
print "Row/column to flip: "
ans = \$stdin.gets.strip

if @columns.include? ans
flip_column @columns.index(ans)
moves += 1
elsif @rows.include? ans
flip_row @rows.index(ans)
moves += 1
else
puts "invalid input: " + ans
end
end

puts "", "you solved the game in #{moves} moves", self
end

# the target formation as a string
def target
format_array @target
end

# the current formation as a string
def to_s
format_array @board
end

############################################################
private

def solved?
@board == @target
end

# flip a random number of bits on the board
def randomize_board
(@size + rand(@size)).times do
flip_bit rand(@size), rand(@size)
end
end

# generate a random number of flip_row/flip_column calls
def generate_target
orig_board = @board.clone
(@size + rand(@size)).times do
rand(2).zero? ? flip_row( rand(@size) ) : flip_column( rand(@size) )
end
target, @board = @board, orig_board
target
end

def flip_row(row)
@size.times {|col| flip_bit(row, col)}
end

def flip_column(col)
@size.times {|row| flip_bit(row, col)}
end

def flip_bit(row, col)
@board[@size * row + col] ^= 1
end

def format_array(ary)
str = "   " + @columns.join(" ") + "\n"
@size.times do |row|
str << "%2s " % @rows[row] + ary[@size*row, @size].join(" ") + "\n"
end
str
end
end

######################################################################
begin
FlipBoard.new(ARGV.shift.to_i).play
rescue => e
puts e.message
end
```

Sample game:

```\$ ruby flipping_bits.rb 3
your target:
a b c
1 1 0 1
2 0 1 1
3 0 1 0

move 0:
a b c
1 0 0 1
2 0 0 0
3 0 0 1
Row/column to flip: 1

move 1:
a b c
1 1 1 0
2 0 0 0
3 0 0 1
Row/column to flip: b

move 2:
a b c
1 1 0 0
2 0 1 0
3 0 1 1
Row/column to flip: c

you solved the game in 3 moves
a b c
1 1 0 1
2 0 1 1
3 0 1 0
```

## Rust

```// For random generation
extern crate rand;

// For fmt::Display
use std::fmt;
// For I/O (stdin, stdout, etc)
use std::io::prelude::*;

use rand::Rng;

/// A simple struct for a board
struct Board {
/// The cells of the board
cells: Vec<bool>,
/// The size of the board
size: usize,
}

// Functions for the Board struct
impl Board {
/// Generate a new, empty board, of size >= 1
///
/// Returns a Board in the "off" state, where all cells are 0.
/// If a size of 0 is given, a Board of size 1 will be created instead.
/// A mutable board is required for using Board::fliprow and Board::flipcol functions.
///
/// ```
/// let mut board: Board = Board::new(3);
/// ```
fn new(size: usize) -> Board {
// Ensure we make a board with a non-zero size
if size > 0 {
Board {
cells: vec![false; size * size],
size,
}
} else {
Board::new(1)
}
}

/// Flip the specified row
///
/// Returns true if the row is within the size, false otherwise.
///
/// ```
/// let mut board: Board = Board::new(3);
/// board.fliprow(1);
/// ```
fn fliprow(&mut self, row: usize) -> bool {
// Check constraints
if row > self.size {
return false;
}
// Starting position in the vector
let start = row * self.size;
// Loop through the vector row
for i in start..start + self.size {
self.cells[i] = !self.cells[i];
}
true
}

/// Flip the specified column
///
/// Returns true if the column is within the size, false otherwise.
///
/// ```
/// let mut board: Board = Board::new(3);
/// board.flipcol(0);
/// ```
fn flipcol(&mut self, col: usize) -> bool {
// Check constraints
if col > self.size {
return false;
}
// Loop through the vector column
for i in 0..self.size {
self.cells[col + i * self.size] = !self.cells[col + i * self.size];
}
true
}

/// Generate a random board
///
/// Returns a Board in a random state.
/// If a size of 0 is given, a Board of size 1 will be created instead.
///
/// ```
/// let target: Board = Board::random(3);
/// ```
fn random<R: Rng>(rng: &mut R, size: usize) -> Board {
// Ensure we make a board with a non-zero size
if size == 0 {
return Board::random(rng, 1);
}

// Make a vector of the board size with random bits
let cells = (0..size * size)
.map(|_| rng.gen::<bool>())
.collect::<Vec<_>>();
// Return the random board
Board { cells, size }
}
}

impl PartialEq for Board {
fn eq(&self, rhs: &Board) -> bool {
self.cells == rhs.cells
}
}

// Implement the Display format, used with `print!("{}", &board);`
impl fmt::Display for Board {
// Example output:
//   0 1 2
// 0 0 1 0
// 1 1 0 0
// 2 0 1 1
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
// Get the string width of the size of the board
let width = (self.size - 1).to_string().len();
// Write the initial spaces (upper left)
write!(f, "{space: >0\$}", width, space = " ")?;
// Write the column numbers
for i in 0..self.size {
write!(f, " {offset:>0\$}", width, offset = i)?;
}
// Newline for rows
writeln!(f)?;
// Loop through the rows
for row in 0..self.size {
// Write the row number
write!(f, "{row:>0\$}", width, row = row)?;
// Loop through the columns
for col in 0..self.size {
// Get the value of the cell as 1 or 0
let p = self.cells[row * self.size + col] as usize;
// Write the column value
write!(f, " {col:>0\$}", width, col = p)?;
}
// Newline for next row
writeln!(f)?;
}
// Return Formatter result
Ok(())
}
}

fn main() {
let mut rng = rand::thread_rng();

// The board size
let size: usize = 3;
// The target board
let target: Board = Board::random(&mut rng, size);
// The user board
let mut board: Board = Board::new(size);
// How many moves taken
let mut moves: u32 = 0;
// Loop until win or quit
'mainloop: loop {
// User input
let mut input: String;
// Write the boards
println!("Target:\n{}\nBoard:\n{}", &target, &board);
// User input loop
'userinput: loop {
// Prompt
print!("\nFlip? [q|[r|c]#] ");
// Flush stdout to write the previous print, if we can't then exit
match std::io::stdout().flush() {
Ok(_) => {}
Err(e) => {
println!("Error: cannot flush stdout: {}", e);
break 'mainloop;
}
};
// Reset input for each loop
input = String::new();
// Read user input
match std::io::stdin().read_line(&mut input) {
Ok(_) => {
input = input.trim().to_string();
// Get the first character
let rc: char = match input.chars().next() {
Some(c) => c,
None => {
println!("Error: No input");
continue 'userinput;
}
};
// Make sure input is r, c, or q
if rc != 'r' && rc != 'c' && rc != 'q' {
println!("Error: '{}': Must use 'r'ow or 'c'olumn or 'q'uit", rc);
continue 'userinput;
}
// If input is q, exit game
if rc == 'q' {
println!("Thanks for playing!");
break 'mainloop;
}
// If input is r or c, get the number after
let n: usize = match input[1..].to_string().parse() {
Ok(x) => {
// If we're within bounds, return the parsed number
if x < size {
x
} else {
println!(
"Error: Must specify a row or column within size({})",
size
);
continue 'userinput;
}
}
Err(_) => {
println!(
"Error: '{}': Unable to parse row or column number",
input[1..].to_string()
);
continue 'userinput;
}
};
// Flip the row or column specified
match rc {
'r' => board.fliprow(n),
'c' => board.flipcol(n),
_ => {
// We want to panic here because should NEVER
// have anything other than 'r' or 'c' here
panic!("How did you end up here?");
}
};
// Increment moves
moves += 1;
println!("Moves taken: {}", moves);
break 'userinput;
}
Err(e) => {
println!("Error reading input: {}", e);
break 'mainloop;
}
}
} // 'userinput
if board == target {
println!("You win!");
break;
}
} // 'mainloop
}
```
Output:
```Target:
0 1 2
0 1 0 0
1 0 0 0
2 0 1 1

Board:
0 1 2
0 0 0 0
1 0 0 0
2 0 0 0

Flip? [q|[r|c]#] r1
Moves taken: 1
Target:
0 1 2
0 1 0 0
1 0 0 0
2 0 1 1

Board:
0 1 2
0 0 0 0
1 1 1 1
2 0 0 0
```

## Scala

### Java Swing Interoperability

Works with: Scala version 2.13
```import java.awt.{BorderLayout, Color, Dimension, Font, Graphics, Graphics2D, Rectangle, RenderingHints}
import java.awt.event.{MouseAdapter, MouseEvent}

import javax.swing.{JFrame, JPanel}

object FlippingBitsGame extends App {

class FlippingBitsGame extends JPanel {
private val maxLevel: Int = 7
private val box: Rectangle = new Rectangle(120, 90, 400, 400)

private var n: Int = maxLevel

private var grid: Array[Array[Boolean]] = _
private var target: Array[Array[Boolean]] = _

private var solved: Boolean = true

override def paintComponent(gg: Graphics): Unit = {
def drawGrid(g: Graphics2D): Unit = {
if (solved) g.drawString("Solved! Click here to play again.", 180, 600)
else g.drawString("Click next to a row or a column to flip.", 170, 600)
val size: Int = box.width / n
for {r <- 0 until n
c <- 0 until n} {
g.setColor(if (grid(r)(c)) Color.blue else Color.orange)
g.fillRect(box.x + c * size, box.y + r * size, size, size)
g.setColor(getBackground)
g.drawRect(box.x + c * size, box.y + r * size, size, size)
g.setColor(if (target(r)(c)) Color.blue else Color.orange)
g.fillRect(7 + box.x + c * size, 7 + box.y + r * size, 10, 10)
}
}

super.paintComponent(gg)
val g: Graphics2D = gg.asInstanceOf[Graphics2D]
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON)
drawGrid(g)
}

private def printGrid(msg: String, g: Array[Array[Boolean]]): Unit = {
println(msg)
for (row <- g) println(row.mkString(", "))
println()
}

private def startNewGame(): Unit = {
val rand = scala.util.Random

if (solved) {
val minLevel: Int = 3
n = if (n == maxLevel) minLevel else n + 1
grid = Array.ofDim[Boolean](n, n)
target = Array.ofDim[Boolean](n, n)

do {
def shuffle(): Unit = for (i <- 0 until n * n)
if (rand.nextBoolean()) flipRow(rand.nextInt(n)) else flipCol(rand.nextInt(n))

shuffle()
for (i <- grid.indices) grid(i).copyToArray(target(i)) //, n)
shuffle()
} while (solved(grid, target))
solved = false
printGrid("The target", target)
printGrid("The board", grid)
}
}

private def solved(a: Array[Array[Boolean]], b: Array[Array[Boolean]]): Boolean =
a.indices.forall(i => a(i) sameElements b(i))

private def flipRow(r: Int): Unit = for (c <- 0 until n) grid(r)(c) ^= true

private def flipCol(c: Int): Unit = for (row <- grid) row(c) ^= true

setPreferredSize(new Dimension(640, 640))
setBackground(Color.white)
setFont(new Font("SansSerif", Font.PLAIN, 18))
startNewGame()
addMouseListener(new MouseAdapter() {
override def mousePressed(e: MouseEvent): Unit = {
if (solved) startNewGame()
else {
val x: Int = e.getX
val y: Int = e.getY
if (box.contains(x, y)) return
if (x > box.x && x < box.x + box.width) flipCol((x - box.x) / (box.width / n))
else if (y > box.y && y < box.y + box.height) flipRow((y - box.y) / (box.height / n))
solved = solved(grid, target)
printGrid(if (solved) "Solved!" else "The board", grid)
}
repaint()
}
})

}

new JFrame("Flipping Bits Game") {
add(new FlippingBitsGame(), BorderLayout.CENTER)
pack()
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE)
setLocationRelativeTo(null)
setResizable(false)
setVisible(true)
}

}
```
 This example does not show the output mentioned in the task description on this page (or a page linked to from here). Please ensure that it meets all task requirements and remove this message. Note that phrases in task descriptions such as "print and display" and "print and show" for example, indicate that (reasonable length) output be a part of a language's solution.

## Swift

Works with: Swift 2.0
```import Foundation

struct Board: Equatable, CustomStringConvertible {
let size: Int
private var tiles: [Bool]

init(size: Int) {
self.size = size
tiles = Array(count: size * size, repeatedValue: false)
}

subscript(x: Int, y: Int) -> Bool {
get {
return tiles[y * size + x]
}
set {
tiles[y * size + x] = newValue
}
}

mutating func randomize() {
for i in 0..<tiles.count {
tiles[i] = Bool(random() % 2)
}
}

mutating func flipRow(row: Int) {
for i in 0..<size {
self[row, i] = !self[row, i]
}
}

mutating func flipColumn(column: Int) {
for i in 0..<size {
self[i, column] = !self[i, column]
}
}

var description: String {
var desc = "\n\ta\tb\tc\n"
for i in 0..<size {
desc += "\(i+1):\t"
for j in 0..<size {
desc += "\(Int(self[i, j]))\t"
}
desc += "\n"
}

return desc
}
}

func ==(lhs: Board, rhs: Board) -> Bool {
return lhs.tiles == rhs.tiles
}

class FlippingGame: CustomStringConvertible {

var board: Board
var target: Board
var solved: Bool { return board == target }

init(boardSize: Int) {
target = Board(size: 3)
board = Board(size: 3)
generateTarget()
}

func generateTarget() {
target.randomize()
board = target
let size = board.size
while solved {
for _ in 0..<size + (random() % size + 1) {
if random() % 2 == 0 {
board.flipColumn(random() % size)
}
else {
board.flipRow(random() % size)
}
}
}
}

func getMove() -> Bool {
print(self)
print("Flip what? ", terminator: "")

guard
let move = readLine(stripNewline: true)
where move.characters.count == 1
else { return false }

var moveValid = true

if let row = Int(move) {
board.flipRow(row - 1)
}
else if let column = move.lowercaseString.utf8.first where column < 100 && column > 96  {
board.flipColumn(numericCast(column) - 97)
}
else {
moveValid = false
}

return moveValid
}

var description: String {
var str = ""
print("Target: \n \(target)", toStream: &str)
print("Board: \n \(board)", toStream: &str)

return str
}
}

func playGame(game: FlippingGame) -> String {
game.generateTarget()
var numMoves = 0
while !game.solved {
numMoves++
print("Move #\(numMoves)")
while !game.getMove() {}
}
print("You win!")
print("Number of moves: \(numMoves)")
print("\n\nPlay Again? ", terminator: "")

return readLine(stripNewline: true)!.lowercaseString
}

let game = FlippingGame(boardSize: 3)
repeat { } while playGame(game) == "y"
```
Output:
```Move #1
Target:

a	b	c
1:	1	1	0
2:	0	0	1
3:	1	0	1

Board:

a	b	c
1:	0	1	0
2:	1	0	1
3:	0	0	1

Flip what? a
You win!
Number of moves: 1

Play Again? n

```

## Tcl

Works with: Tcl version 8.6
```package require Tcl 8.6

oo::class create Flip {
variable board target s
constructor {size} {
set s \$size
set target [my RandomConfiguration]
set board \$target
while {\$board eq \$target} {
for {set i 0} {\$i < \$s} {incr i} {
if {rand()<.5} {
my SwapRow \$i
}
if {rand()<.5} {
my SwapColumn \$i
}
}
}
}

method RandomConfiguration {{p 0.5}} {
for {set row 0} {\$row < \$s} {incr row} {
set r {}
for {set col 0} {\$col < \$s} {incr col} {
lappend r [expr {rand() < \$p}]
}
lappend result \$r
}
return \$result
}

method SwapRow {rowId} {
for {set i 0} {\$i < \$s} {incr i} {
lset board \$rowId \$i [expr {![lindex \$board \$rowId \$i]}]
}
}
method SwapColumn {columnId} {
for {set i 0} {\$i < \$s} {incr i} {
lset board \$i \$columnId [expr {![lindex \$board \$i \$columnId]}]
}
}

method Render {configuration {prefixes {}}} {
join [lmap r \$configuration p \$prefixes {
format %s%s \$p [join [lmap c \$r {string index ".X" \$c}] ""]
}] "\n"
}
method GetInput {prompt} {
puts -nonewline "\${prompt}: "
flush stdout
gets stdin
}

method play {} {
set p0 {}
set p {}
set top [format "%*s " [string length \$s] ""]
for {set i 1;set j 97} {\$i<=\$s} {incr i;incr j} {
append top [format %c \$j]
lappend p [format "%*d " [string length \$s] \$i]
lappend p0 [format "%*s " [string length \$s] ""]
}

set moves 0
puts "You are trying to get to:\n[my Render \$target \$p0]\n"
while true {
puts "Current configuration (#\$moves):\n\$top\n[my Render \$board \$p]"

# Test for if we've won
if {\$board eq \$target} break

# Ask the user for a move
set i [my GetInput "Pick a column (letter) or row (number) to flip"]

# Parse the move and apply it
if {[string is lower -strict \$i] && [set c [expr {[scan \$i "%c"] - 97}]]<\$s} {
my SwapColumn \$c
incr moves
} elseif {[string is integer -strict \$i] && \$i>0 && \$i<=\$s} {
my SwapRow [expr {\$i - 1}]
incr moves
} else {
puts "Error: bad selection"
}
puts ""
}
puts "\nYou win! (You took \$moves moves.)"
}
}

Flip create flip 3
flip play
```
Example game:
```You are trying to get to:
.XX
XXX
X.X

Current configuration (#0):
abc
1 .X.
2 ..X
3 X..
Pick a column (letter) or row (number) to flip: 2

Current configuration (#1):
abc
1 .X.
2 XX.
3 X..
Pick a column (letter) or row (number) to flip: c

Current configuration (#2):
abc
1 .XX
2 XXX
3 X.X

You win! (You took 2 moves.)
```

## Uiua

Uiua doesn't really support user input, so this game plays itself (no cheating though!). You can run it in Uiua Pad though.

```S ← 9
Fr ← ⊙◌⍜⊡¬⊙.
Fc ← ⊙◌⍉Fr⊙(⍉.)
Shuffle ← ⍥(⟨Fr|Fc⟩<0.5⚂ ⌊×S⚂)×3S
T ← Shuffle ↯S_S 0 # Target setup. Omit `Shuffle` for plain grid.
D ← /+/+⌵-T

# Could use A*, but this is easily solved without it.
# ◌astar(⊂⊃(≡Fr|≡Fc)⇡S¤|÷S D|=0D)
⟜[∘] Shuffle T # Shuffle and keep a copy for the output.
◌⍢(

⊂⊃(≡Fr|≡Fc)⇡S¤ # All neighbours.
⊚=/↧.≡D.       # Find min dist, get indices that give that.
⊡⊢             # Pick first one. ⊡(⊡⌊×⚂⧻.) to pick at random.
⊙⊂.            # Save a copy of the new state.
| ≠0D
)
⟜(\$"_ steps."-1⧻)⇌```
Output:

Sample output for a simple grid, with the target state being all zeros.

```"4 steps."
╭─
╷ 1 0 1 0
╷ 1 0 1 0
0 1 0 1
0 1 0 1

0 1 0 1
1 0 1 0
0 1 0 1
0 1 0 1

0 0 0 1
1 1 1 0
0 0 0 1
0 0 0 1

0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1

0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
╯
```

## Wren

Translation of: Kotlin
Library: Wren-ioutil
Library: Wren-str
```import "random" for Random
import "./ioutil" for Input
import "./str" for Str

var rand = Random.new()
var target = List.filled(3, null)
var board  = List.filled(3, null)
for (i in 0..2) {
target[i] = List.filled(3, 0)
board[i]  = List.filled(3, 0)
for (j in 0..2) target[i][j] = rand.int(2)
}

var flipRow = Fn.new { |r|
for (c in 0..2) board[r][c] = (board[r][c] == 0) ? 1 : 0
}

var flipCol = Fn.new { |c|
for (r in 0..2) board[r][c] = (board[r][c] == 0) ? 1 : 0
}

/* starting from the target we make 9 random row or column flips */
var initBoard = Fn.new {
for (i in 0..2) {
for (j in 0..2) board[i][j] = target[i][j]
}
for (i in 1..9) {
var rc = rand.int(2)
if (rc == 0) {
flipRow.call(rand.int(3))
} else {
flipCol.call(rand.int(3))
}
}
}

var printBoard = Fn.new { |label, isTarget|
var a = (isTarget) ? target : board
System.print("%(label):")
System.print("  | a b c")
System.print("---------")
for (r in 0..2) {
System.write("%(r + 1) |")
for (c in 0..2) System.write(" %(a[r][c])")
System.print()
}
System.print()
}

var gameOver = Fn.new {
for (r in 0..2) {
for (c in 0..2) if (board[r][c] != target[r][c]) return false
}
return true
}

// initialize board and ensure it differs from the target i.e. game not already over!
while (true) {
initBoard.call()
if (!gameOver.call()) break
}

printBoard.call("TARGET", true)
printBoard.call("OPENING BOARD", false)
var flips = 0

while (true) {
var isRow = true
var n = -1
var prompt = "Enter row number or column letter to be flipped: "
var ch = Str.lower(Input.option(prompt, "123abcABC"))
if (ch == "1" || ch == "2" || ch == "3") {
n = ch.bytes[0] - 49
} else {
isRow = false
n = ch.bytes[0] - 97
}
flips = flips + 1
if (isRow) flipRow.call(n) else flipCol.call(n)
var plural = (flips == 1) ? "" : "S"
printBoard.call("\nBOARD AFTER %(flips) FLIP%(plural)", false)
if (gameOver.call()) break
}

var plural = (flips == 1) ? "" : "s"
System.print("You've succeeded in %(flips) flip%(plural)")
```
Output:

Sample (lucky!) game:

```TARGET:
| a b c
---------
1 | 1 1 0
2 | 1 1 1
3 | 0 0 0

OPENING BOARD:
| a b c
---------
1 | 0 0 1
2 | 1 1 1
3 | 0 0 0

Enter row number or column letter to be flipped: 1

BOARD AFTER 1 FLIP:
| a b c
---------
1 | 1 1 0
2 | 1 1 1
3 | 0 0 0

You've succeeded in 1 flip
```