# 15 puzzle game

15 puzzle game
You are encouraged to solve this task according to the task description, using any language you may know.

Implement the Fifteen Puzzle Game.

The   15-puzzle   is also known as:

•   Fifteen Puzzle
•   Gem Puzzle
•   Boss Puzzle
•   Game of Fifteen
•   Mystic Square
•   14-15 Puzzle
•   and some others.

## 11l

```T Puzzle
position = 0
[Int = String] items

F main_frame()
V& d = .items
print(‘+-----+-----+-----+-----+’)
print(‘|#.|#.|#.|#.|’.format(d[1], d[2], d[3], d[4]))
print(‘+-----+-----+-----+-----+’)
print(‘|#.|#.|#.|#.|’.format(d[5], d[6], d[7], d[8]))
print(‘+-----+-----+-----+-----+’)
print(‘|#.|#.|#.|#.|’.format(d[9], d[10], d[11], d[12]))
print(‘+-----+-----+-----+-----+’)
print(‘|#.|#.|#.|#.|’.format(d[13], d[14], d[15], d[16]))
print(‘+-----+-----+-----+-----+’)

F format(=ch)
ch = ch.trim(‘ ’)
I ch.len == 1
R ‘  ’ch‘  ’
E I ch.len == 2
R ‘  ’ch‘ ’
E
assert(ch.empty)
R ‘     ’

F change(=to)
V fro = .position
L(a, b) .items
I b == .format(String(to))
to = a
L.break
swap(&.items[fro], &.items[to])
.position = to

F build_board(difficulty)
L(i) 1..16
.items[i] = .format(String(i))
V tmp = 0
L(a, b) .items
I b == ‘  16 ’
.items[a] = ‘     ’
tmp = a
L.break
.position = tmp
Int diff
I difficulty == 0
diff = 10
E I difficulty == 1
diff = 50
E
diff = 100
L 0 .< diff
V lst = .valid_moves()
[Int] lst1
L(j) lst
lst1.append(Int(j.trim(‘ ’)))
.change(lst1[random:(lst1.len)])

F valid_moves()
V pos = .position
I pos C [6, 7, 10, 11]
R [.items[pos - 4], .items[pos - 1], .items[pos + 1], .items[pos + 4]]
E I pos C [5, 9]
R [.items[pos - 4], .items[pos + 4], .items[pos + 1]]
E I pos C [8, 12]
R [.items[pos - 4], .items[pos + 4], .items[pos - 1]]
E I pos C [2, 3]
R [.items[pos - 1], .items[pos + 1], .items[pos + 4]]
E I pos C [14, 15]
R [.items[pos - 1], .items[pos + 1], .items[pos - 4]]
E I pos == 1
R [.items[pos + 1], .items[pos + 4]]
E I pos == 4
R [.items[pos - 1], .items[pos + 4]]
E I pos == 13
R [.items[pos + 1], .items[pos - 4]]
E
assert(pos == 16)
R [.items[pos - 1], .items[pos - 4]]

F game_over()
V flag = 0B
L(a, b) .items
I b != ‘     ’
I a == Int(b.trim(‘ ’))
flag = 1B
E
flag = 0B
R flag

V g = Puzzle()
g.build_board(Int(input("Enter the difficulty : 0 1 2\n2 => highest 0 => lowest\n")))
g.main_frame()
print(‘Enter 0 to exit’)
L
print("Hello user:\nTo change the position just enter the no. near it")
V lst = g.valid_moves()
[Int] lst1
L(i) lst
lst1.append(Int(i.trim(‘ ’)))
print(i.trim(‘ ’)" \t", end' ‘’)
print()
V x = Int(input())
I x == 0
L.break
E I x !C lst1
print(‘Wrong move’)
E
g.change(x)
g.main_frame()
I g.game_over()
print(‘You WON’)
L.break```
Output:

The same as in Python.

## 68000 Assembly

This is an entire Sega Genesis game, tested in the Fusion emulator. Thanks to Keith S. of Chibiakumas for the cartridge header, font routines, and printing logic. I programmed the actual game logic. This code can be copied and pasted into a text file and assembled as-is using vasmm68k_mot_win32.exe, no includes or incbins necessary (even the bitmap font is here too.)

```;15 PUZZLE GAME
;Ram Variables
Cursor_X equ \$00FF0000		;Ram for Cursor Xpos
Cursor_Y equ \$00FF0000+1	;Ram for Cursor Ypos

GameRam equ \$00FF1000		;Ram for where the pieces are
GameRam_End equ \$00FF100F	;the last valid slot in the array
;Video Ports
VDP_data	EQU	\$C00000	; VDP data, R/W word or longword access only
VDP_ctrl	EQU	\$C00004	; VDP control, word or longword writes only

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; 					VECTOR TABLE
;org \$00000000
DC.L	\$00FFFFFE		;SP register value
DC.L	ProgramStart	;Start of Program Code
DC.L	IntReturn		; bus err
DC.L	IntReturn		; illegal inst
DC.L	IntReturn		; divzero
DC.L	IntReturn		; CHK
DC.L	IntReturn		; TRAPV
DC.L	IntReturn		; privilege viol
DC.L	IntReturn		; TRACE
DC.L	IntReturn		; Line A (1010) emulator
DC.L	IntReturn		; Line F (1111) emulator
DC.L	IntReturn,IntReturn,IntReturn,IntReturn		; Reserved /Coprocessor/Format err/ Uninit Interrupt
DC.L	IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn
DC.L	IntReturn		; spurious interrupt
DC.L	IntReturn		; IRQ level 1
DC.L	IntReturn		; IRQ level 2 EXT
DC.L	IntReturn		; IRQ level 3
DC.L	IntReturn		; IRQ level 4 Hsync
DC.L	IntReturn		; IRQ level 5
DC.L	IntReturn		; IRQ level 6 Vsync
DC.L	IntReturn		; IRQ level 7 (NMI)
;org \$00000080
;TRAPS
DC.L	IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn
DC.L	IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn
;org \$000000C0
;FP/MMU
DC.L	IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn
DC.L	IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn,IntReturn

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
DC.B	"SEGA GENESIS    "	        ;System Name	MUST TAKE UP 16 BYTES, USE PADDING IF NECESSARY
DC.B	"(C)PDS  "			;Copyright	MUST TAKE UP 8 BYTES, USE PADDING IF NECESSARY
DC.B	"2022.JUN"			;Date		MUST TAKE UP 8 BYTES, USE PADDING IF NECESSARY
CARTNAME:
DC.B 	"15 PUZZLE"
CARTNAME_END:
DS.B 48-(CARTNAME_END-CARTNAME)	;ENSURES PROPER SPACING
CARTNAMEALT:
DC.B	"15 PUZZLE"
CARTNAMEALT_END:
DS.B 48-(CARTNAMEALT_END-CARTNAMEALT)	;ENSURES PROPER SPACING
gameID:
DC.B	"GM PUPPY001-00"	        ;TT NNNNNNNN-RR T=Type (GM=Game) N=game Num  R=Revision
DC.W	\$0000				;16-bit Checksum (Address \$000200+)
CTRLDATA:
DC.B	"J               "	        ;Control Data (J=3button K=Keyboard 6=6button C=cdrom)
;(MUST TAKE UP 16 BYTES, USE PADDING IF NECESSARY)
ROMSTART:
DC.L	\$00000000			;ROM Start
ROMLEN:
DC.L	\$003FFFFF			;ROM Length
RAMSTART:
DC.L	\$00FF0000
RAMEND:
DC.L	\$00FFFFFF	;RAM start/end (fixed)

DC.B	"            "		;External RAM Data	(MUST TAKE UP 12 BYTES, USE PADDING IF NECESSARY)
DC.B	"            "		;Modem Data		(MUST TAKE UP 12 BYTES, USE PADDING IF NECESSARY)
MEMO:
DC.B	"                                        "      ;(MUST TAKE UP 40 BYTES, USE PADDING IF NECESSARY)
REGION:
DC.B	"JUE             "	;Regions Allowed        (MUST TAKE UP 16 BYTES, USE PADDING IF NECESSARY)
even

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;					Generic Interrupt Handler
IntReturn:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;					Program Start
ProgramStart:
move.b (\$A10001),D0		;A10001 test the hardware version
and.b #\$0F,D0
beq	NoTmss				;branch if no TMSS chip
move.l #'SEGA',(\$A14000);A14000 disable TMSS
NoTmss:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;					Set Up Graphics

lea VDPSettings,A5		      ;Initialize Screen Registers
move.l #VDPSettingsEnd-VDPSettings,D1 ;length of Settings

move.w (VDP_ctrl),D0	              ;C00004 read VDP status (interrupt acknowledge?)
move.l #\$00008000,d5	              ;VDP Reg command (%8rvv)

NextInitByte:
move.b (A5)+,D5			      ;get next video control byte
move.w D5,(VDP_ctrl)	              ;C00004 send write register command to VDP
;   8RVV - R=Reg V=Value
add.w #\$0100,D5			      ;point to next VDP register
dbra D1,NextInitByte	              ;loop for rest of block

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;       Set up palette

;Define palette
move.l #\$C0000000,d0	;Color 0 (background)
move.l d0,VDP_Ctrl
;        ----BBB-GGG-RRR-
move.w #%0000011000000000,VDP_data

move.l #\$C01E0000,d0	;Color 15 (Font)
move.l d0,VDP_Ctrl
move.w #%0000000011101110,VDP_data

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;					Set up Font
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; FONT IS 1BPP, THIS ROUTINE CONVERTS IT TO A 4BPP FORMAT.
lea Font,A1					 ;Font Address in ROM
move.l #Font_End-Font,d6	                 ;Our font contains 96 letters 8 lines each

move.l #\$40000000,(VDP_Ctrl);Start writes to VRAM address \$0000
NextFont:
move.b (A1)+,d0		;Get byte from font
moveq.l #7,d5		;Bit Count (8 bits)
clr.l d1		;Reset BuildUp Byte

Font_NextBit:			;1 color per nibble = 4 bytes

rol.l #3,d1		;Shift BuildUp 3 bits left
roxl.b #1,d0		;Shift a Bit from the 1bpp font into the Pattern
roxl.l #1,d1		;Shift bit into BuildUp
dbra D5,Font_NextBit    ;Next Bit from Font

move.l d1,d0		; Make fontfrom Color 1 to color 15
rol.l #1,d1		;Bit 1
or.l d0,d1
rol.l #1,d1		;Bit 2
or.l d0,d1
rol.l #1,d1		;Bit 3
or.l d0,d1

move.l d1,(VDP_Data);Write next Long of char (one line) to VDP
dbra d6,NextFont	;Loop until done

clr.b Cursor_X		;Clear Cursor XY
clr.b Cursor_Y

;Turn on screen
move.w	#\$8144,(VDP_Ctrl);C00004 reg 1 = 0x44 unblank display

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; all of the above was just the prep work to boot the Sega Genesis, and had nothing to do with a 15 Puzzle.
; That's hardware for you!

LEA GameRam,A0
;load the initial state of the puzzle. There is no randomization here unfortunately, as creating a sufficient pseudo-RNG
;to make the game "believable" is more difficult than programming the game itself!
;so instead we'll start in such a manner that the player has to do quite a bit of work to win.
MOVE.B #'F',(A0)+
MOVE.B #'E',(A0)+
MOVE.B #'D',(A0)+
MOVE.B #'C',(A0)+
MOVE.B #'B',(A0)+
MOVE.B #'A',(A0)+
MOVE.B #'9',(A0)+
MOVE.B #'8',(A0)+
MOVE.B #'7',(A0)+
MOVE.B #'6',(A0)+
MOVE.B #'5',(A0)+
MOVE.B #'4',(A0)+
MOVE.B #'3',(A0)+
MOVE.B #'2',(A0)+
MOVE.B #'1',(A0)+
MOVE.B #' ',(A0)+

;puzzle will look like:
;FEDC
;BA98
;7654
;321

main:

;adjust the number of these as you see fit.
;this affects the game's overall speed.
JSR waitVBlank
JSR waitVBlank
JSR waitVBlank
JSR waitVBlank
JSR waitVBlank
JSR waitVBlank
JSR waitVBlank
JSR waitVBlank
JSR waitVBlank
JSR waitVBlank

;find where the blank space is among GameRAM
LEA GameRAM,a0
MOVE.B #' ',D0
JSR REPNE_SCASB
MOVE.L A0,A1

;;;;;;;;;;;;;;;;;;; check controller presses

BNE JoyNotUp
MOVEM.L D0/A1,-(SP)
CMPA.L #GameRam_End,A1
BHI .doNothing
;OTHERWISE SWAP THE EMPTY SPACE WITH THE BYTE BELOW IT.
MOVE.B (A1),D7
MOVE.B (A0),(A1)
MOVE.B D7,(A0)
.doNothing
MOVEM.L (SP)+,D0/A1
bra vdraw
JoyNotUp:
BNE JoyNotDown
MOVEM.L D0/A1,-(SP)

SUBA.L #4,A1		;CHECK ONE ROW ABOVE WHERE WE ARE
CMPA.L #GameRam,A1
BCS .doNothing		;if A1-4 IS BELOW THE START OF GAME RAM, DON'T MOVE
;OTHERWISE SWAP THE EMPTY SPACE WITH THE BYTE ABOVE IT.
MOVE.B (A1),D7
MOVE.B (A0),(A1)
MOVE.B D7,(A0)
.doNothing:
MOVEM.L (SP)+,D0/A1
bra vdraw
JoyNotDown:
BNE JoyNotLeft
MOVEM.L D0/A1,-(SP)
MOVE.L A1,D4
MOVE.L A0,D3
AND.L #3,D4
AND.L #3,D3
CMP.L D3,D4
BCS .doNothing
;OTHERWISE SWAP THE EMPTY SPACE WITH THE BYTE TO THE LEFT
MOVE.B (A1),D7
MOVE.B (A0),(A1)
MOVE.B D7,(A0)
.doNothing:
MOVEM.L (SP)+,D0/A1
bra vdraw
JoyNotLeft:
BNE JoyNotRight
MOVEM.L D0/A1,-(SP)
SUBA.L #1,A1
MOVE.L A1,D4
MOVE.L A0,D3
AND.L #3,D4
AND.L #3,D3
CMP.L D3,D4
BHI .doNothing
;OTHERWISE SWAP THE EMPTY SPACE WITH THE BYTE TO THE RIGHT
MOVE.B (A1),D7
MOVE.B (A0),(A1)
MOVE.B D7,(A0)
.doNothing:
MOVEM.L (SP)+,D0/A1
bra vdraw
JoyNotRight:

vdraw:
;this actually draws the current state of the puzzle to the screen.
LEA GameRam,A0
CLR.B (Cursor_X)   ;reset text cursors to top left of screen
CLR.B (Cursor_Y)

;draw the puzzle

;anything insize a REPT N...ENDR block is in-lined N times, back to back.
rept 4

MOVE.B (A0)+,D0
JSR PrintChar

MOVE.B (A0)+,D0
JSR PrintChar

MOVE.B (A0)+,D0
JSR PrintChar

MOVE.B (A0)+,D0
JSR PrintChar         ;we just finished drawing one row of the puzzle. Now, begin a new line and continue drawing.

jsr newline
endr

checkIfWin:
;YES THIS IS MESSY, I TRIED IT WITH A LOOP BUT IT WOULDN'T WORK SO I JUST UNROLLED THE LOOP.
LEA GameRam,a4
MOVE.B (A4)+,D5
CMP.B #'1',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'2',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'3',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'4',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'5',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'6',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'7',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'8',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'9',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'A',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'B',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'C',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'D',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'E',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #'F',D5
BNE .keepGoing

MOVE.B (A4)+,D5
CMP.B #' ',D5
BNE .keepGoing

clr.b (Cursor_X)
move.b #7,(Cursor_Y)
LEA victoryMessage,a3
jsr PrintString
jmp *  ;game freezes after you win.

.keepGoing:
;it's unlikely that the label "main" is in range of here so I didn't bother checking and just assumed it was out of range.
;Otherwise I would have said "BEQ main" instead of BNE .keepGoing
jmp main

VictoryMessage:
DC.B "A WINNER IS YOU",255
EVEN

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
REPNE_SCASB:
;INPUT:
;A0 = POINTER TO START OF MEMORY
;D0 = THE BYTE TO SEARCH FOR
;OUTPUT = A0 POINTS TO THE BYTE THAT CONTAINED D0
MOVE.B (A0),D1
CMP.B D0,D1
BEQ .done
BRA REPNE_SCASB
.done:
RTS

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

move.b #%01000000,(\$A1000B)	; Set direction IOIIIIII (I=In O=Out)
move.l #\$A10003,a0		;RW port for player 1

move.b  #\$40,(a0)	; TH = 1
nop		;Delay
nop
move.b  (a0),d2		; d0.b = --CBRLDU	Store in D2

move.b	#\$0,(a0)	; TH = 0
nop		;Delay
nop
move.b	(a0),d1		; d1.b = --SA--DU	Store in D1

move.b  #\$40,(a0)	; TH = 1
nop		;Delay
nop
move.b	#\$0,(a0)	; TH = 0
nop		;Delay
nop
move.b  #\$40,(a0)	; TH = 1
nop		;Delay
nop
move.b	(a0),d3		; d1.b = --CBXYZM	Store in D3
move.b	#\$0,(a0)	; TH = 0

clr.l d0			;Clear buildup byte
roxr.b d2
roxr.b d0			;U
roxr.b d2
roxr.b d0			;D
roxr.b d2
roxr.b d0			;L
roxr.b d2
roxr.b d0			;R
roxr.b #5,d1
roxr.b d0			;A
roxr.b d2
roxr.b d0			;B
roxr.b d2
roxr.b d0			;C
roxr.b d1
roxr.b d0			;S

move.l d3,d1
roxl.l #7,d1		;XYZ
and.l #%0000011100000000,d1
or.l d1,d0

move.l d3,d1
roxl.l #8,d1		;M
roxl.l #3,d1
and.l #%0000100000000000,d1
or.l d1,d0

or.l #\$FFFFF000,d0	;Set unused bits to 1

;this returns player 1's buttons into D0 as the following:
;----MZYXSCBARLDU
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
waitVBlank:							;Bit 3 defines if we're in Vblank
MOVE.L d0,-(sp)
.wait:
move.w VDP_ctrl,d0
and.w #%0000000000001000,d0		;See if vblank is running
bne .wait					;wait until it is

waitVBlank2:
move.w VDP_ctrl,d0
and.w #%0000000000001000,d0		;See if vblank is running
beq waitVBlank2					;wait until it isnt
MOVE.L (SP)+,d0
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

PrintChar:				;Show D0 to screen
moveM.l d0-d7/a0-a7,-(sp)
and.l #\$FF,d0			;Keep only 1 byte
sub #32,d0				;No Characters in our font below 32
PrintCharAlt:
Move.L  #\$40000003,d5	;top 4=write, bottom \$3=Cxxx range
clr.l d4					;Tilemap at \$C000+

Move.B (Cursor_Y),D4
rol.L #8,D4				;move \$-FFF to \$-FFF----
rol.L #8,D4
rol.L #7,D4				;2 bytes per tile * 64 tiles per line

Move.B (Cursor_X),D4
rol.L #8,D4				;move \$-FFF to \$-FFF----
rol.L #8,D4
rol.L #1,D4				;2 bytes per tile

MOVE.L	D5,(VDP_ctrl)	; C00004 write next character to VDP
MOVE.W	D0,(VDP_data)	; C00000 store next word of name data

move.b (Cursor_X),d0
cmp.b #39,d0
bls nextpixel_Xok
jsr NewLine			;If we're at end of line, start newline
nextpixel_Xok:
moveM.l (sp)+,d0-d7/a0-a7
rts

PrintString:
move.b (a3)+,d0			;Read a character in from A3
cmp.b #255,d0
beq PrintString_Done	;return on 255
jsr PrintChar			;Print the Character
bra PrintString
PrintString_Done:
rts

NewLine:
clr.b (Cursor_X)			;Zero X
rts

Font:
;1bpp font - 8x8 96 characters
;looks just like your typical "8-bit" font. You'll just have to take my word for it.
DC.B \$00,\$00,\$00,\$00,\$00,\$00,\$00,\$00,\$18,\$3c,\$3c,\$18,\$18,\$00,\$18,\$18
DC.B \$36,\$36,\$12,\$24,\$00,\$00,\$00,\$00,\$00,\$12,\$7f,\$24,\$24,\$fe,\$48,\$00
DC.B \$00,\$04,\$1e,\$28,\$1c,\$0a,\$3c,\$10,\$00,\$62,\$64,\$08,\$10,\$26,\$46,\$00
DC.B \$00,\$18,\$24,\$20,\$12,\$2c,\$44,\$3a,\$18,\$18,\$08,\$10,\$00,\$00,\$00,\$00
DC.B \$08,\$10,\$20,\$20,\$20,\$20,\$10,\$08,\$10,\$08,\$04,\$04,\$04,\$04,\$08,\$10
DC.B \$00,\$10,\$38,\$10,\$28,\$00,\$00,\$00,\$00,\$00,\$10,\$10,\$7c,\$10,\$10,\$00
DC.B \$00,\$00,\$00,\$00,\$0c,\$0c,\$04,\$08,\$00,\$00,\$00,\$00,\$7e,\$00,\$00,\$00
DC.B \$00,\$00,\$00,\$00,\$00,\$18,\$18,\$00,\$01,\$02,\$04,\$08,\$10,\$20,\$40,\$00
DC.B \$1c,\$26,\$63,\$63,\$63,\$32,\$1c,\$00,\$0c,\$1c,\$0c,\$0c,\$0c,\$0c,\$3f,\$00
DC.B \$3e,\$63,\$07,\$1e,\$3c,\$70,\$7f,\$00,\$3f,\$06,\$0c,\$1e,\$03,\$63,\$3e,\$00
DC.B \$0e,\$1e,\$36,\$66,\$7f,\$06,\$06,\$00,\$7e,\$60,\$7e,\$03,\$03,\$63,\$3e,\$00
DC.B \$1e,\$30,\$60,\$7e,\$63,\$63,\$3e,\$00,\$7f,\$63,\$06,\$0c,\$18,\$18,\$18,\$00
DC.B \$3c,\$62,\$72,\$3c,\$4f,\$43,\$3e,\$00,\$3e,\$63,\$63,\$3f,\$03,\$06,\$3c,\$00
DC.B \$00,\$18,\$18,\$00,\$18,\$18,\$00,\$00,\$00,\$0c,\$0c,\$00,\$0c,\$0c,\$04,\$08
DC.B \$00,\$00,\$06,\$18,\$60,\$18,\$06,\$00,\$00,\$00,\$00,\$7e,\$00,\$7e,\$00,\$00
DC.B \$00,\$00,\$60,\$18,\$06,\$18,\$60,\$00,\$1c,\$36,\$36,\$06,\$0c,\$00,\$0c,\$0c
DC.B \$3c,\$42,\$99,\$a1,\$a1,\$99,\$42,\$3c,\$1c,\$36,\$63,\$63,\$7f,\$63,\$63,\$00
DC.B \$7e,\$63,\$63,\$7e,\$63,\$63,\$7e,\$00,\$1e,\$33,\$60,\$60,\$60,\$33,\$1e,\$00
DC.B \$7c,\$66,\$63,\$63,\$63,\$66,\$7c,\$00,\$3f,\$30,\$30,\$3e,\$30,\$30,\$3f,\$00
DC.B \$7f,\$60,\$60,\$7e,\$60,\$60,\$60,\$00,\$1f,\$30,\$60,\$67,\$63,\$33,\$1f,\$00
DC.B \$63,\$63,\$63,\$7f,\$63,\$63,\$63,\$00,\$3f,\$0c,\$0c,\$0c,\$0c,\$0c,\$3f,\$00
DC.B \$03,\$03,\$03,\$03,\$03,\$63,\$3e,\$00,\$63,\$66,\$6c,\$78,\$7c,\$6e,\$67,\$00
DC.B \$30,\$30,\$30,\$30,\$30,\$30,\$3f,\$00,\$63,\$77,\$7f,\$7f,\$6b,\$63,\$63,\$00
DC.B \$63,\$73,\$7b,\$7f,\$6f,\$67,\$63,\$00,\$3e,\$63,\$63,\$63,\$63,\$63,\$3e,\$00
DC.B \$7e,\$63,\$63,\$63,\$7e,\$60,\$60,\$00,\$3e,\$63,\$63,\$63,\$6f,\$66,\$3d,\$00
DC.B \$7e,\$63,\$63,\$67,\$7c,\$6e,\$67,\$00,\$3c,\$66,\$60,\$3e,\$03,\$63,\$3e,\$00
DC.B \$3f,\$0c,\$0c,\$0c,\$0c,\$0c,\$0c,\$00,\$63,\$63,\$63,\$63,\$63,\$63,\$3e,\$00
DC.B \$63,\$63,\$63,\$77,\$3e,\$1c,\$08,\$00,\$63,\$63,\$6b,\$7f,\$7f,\$77,\$63,\$00
DC.B \$63,\$77,\$3e,\$1c,\$3e,\$77,\$63,\$00,\$33,\$33,\$33,\$1e,\$0c,\$0c,\$0c,\$00
DC.B \$7f,\$07,\$0e,\$1c,\$38,\$70,\$7f,\$00,\$00,\$38,\$20,\$20,\$20,\$20,\$38,\$00
DC.B \$80,\$40,\$20,\$10,\$08,\$04,\$02,\$00,\$00,\$1c,\$04,\$04,\$04,\$04,\$1c,\$00
DC.B \$10,\$28,\$44,\$00,\$00,\$00,\$00,\$00,\$00,\$00,\$00,\$00,\$00,\$00,\$7e,\$00
DC.B \$00,\$20,\$10,\$00,\$00,\$00,\$00,\$00,\$00,\$18,\$04,\$1c,\$24,\$2c,\$1c,\$00
DC.B \$00,\$20,\$20,\$38,\$24,\$24,\$38,\$00,\$00,\$00,\$1c,\$20,\$20,\$20,\$1c,\$00
DC.B \$00,\$04,\$04,\$1c,\$24,\$24,\$1c,\$00,\$00,\$00,\$1c,\$24,\$3c,\$20,\$1c,\$00
DC.B \$00,\$18,\$24,\$20,\$30,\$20,\$20,\$00,\$00,\$1c,\$24,\$24,\$1c,\$04,\$3c,\$00
DC.B \$00,\$20,\$20,\$38,\$24,\$24,\$24,\$00,\$00,\$10,\$00,\$10,\$10,\$10,\$10,\$00
DC.B \$08,\$00,\$08,\$08,\$08,\$08,\$28,\$10,\$20,\$20,\$24,\$28,\$30,\$28,\$24,\$00
DC.B \$10,\$10,\$10,\$10,\$10,\$10,\$18,\$00,\$00,\$00,\$40,\$68,\$54,\$54,\$54,\$00
DC.B \$00,\$00,\$28,\$34,\$24,\$24,\$24,\$00,\$00,\$00,\$1c,\$22,\$22,\$22,\$1c,\$00
DC.B \$00,\$00,\$38,\$24,\$24,\$38,\$20,\$20,\$00,\$00,\$1c,\$24,\$24,\$1c,\$04,\$04
DC.B \$00,\$00,\$2c,\$30,\$20,\$20,\$20,\$00,\$00,\$00,\$1c,\$20,\$1c,\$02,\$3c,\$00
DC.B \$00,\$10,\$3c,\$10,\$10,\$14,\$08,\$00,\$00,\$00,\$24,\$24,\$24,\$24,\$1a,\$00
DC.B \$00,\$00,\$24,\$24,\$24,\$14,\$18,\$00,\$00,\$00,\$92,\$92,\$92,\$5a,\$6c,\$00
DC.B \$00,\$00,\$22,\$14,\$08,\$14,\$22,\$00,\$00,\$00,\$24,\$24,\$1c,\$04,\$18,\$00
DC.B \$00,\$00,\$3c,\$04,\$18,\$20,\$3c,\$00,\$00,\$08,\$10,\$10,\$20,\$10,\$10,\$08
DC.B \$18,\$18,\$18,\$18,\$18,\$18,\$18,\$18,\$00,\$10,\$08,\$08,\$04,\$08,\$08,\$10
DC.B \$00,\$00,\$00,\$30,\$4a,\$04,\$00,\$00,\$1c,\$7f,\$00,\$7f,\$55,\$55,\$55,\$00
Font_End:

VDPSettings:
DC.B \$04 ; 0 mode register 1											---H-1M-
DC.B \$04 ; 1 mode register 2											-DVdP---
DC.B \$30 ; 2 name table base for scroll A (A=top 3 bits)				--AAA--- = \$C000
DC.B \$3C ; 3 name table base for window (A=top 4 bits / 5 in H40 Mode)	--AAAAA- = \$F000
DC.B \$07 ; 4 name table base for scroll B (A=top 3 bits)				-----AAA = \$E000
DC.B \$6C ; 5 sprite attribute table base (A=top 7 bits / 6 in H40)		-AAAAAAA = \$D800
DC.B \$00 ; 6 unused register											--------
DC.B \$00 ; 7 background color (P=Palette C=Color)						--PPCCCC
DC.B \$00 ; 8 unused register											--------
DC.B \$00 ; 9 unused register											--------
DC.B \$FF ;10 H interrupt register (L=Number of lines)					LLLLLLLL
DC.B \$00 ;11 mode register 3											----IVHL
DC.B \$81 ;12 mode register 4 (C bits both1 = H40 Cell)					C---SIIC
DC.B \$37 ;13 H scroll table base (A=Top 6 bits)							--AAAAAA = \$FC00
DC.B \$00 ;14 unused register											--------
DC.B \$02 ;15 auto increment (After each Read/Write)						NNNNNNNN
DC.B \$01 ;16 scroll size (Horiz & Vert size of ScrollA & B)				--VV--HH = 64x32 tiles
DC.B \$00 ;17 window H position (D=Direction C=Cells)					D--CCCCC
DC.B \$00 ;18 window V position (D=Direction C=Cells)					D--CCCCC
DC.B \$FF ;19 DMA length count low										LLLLLLLL
DC.B \$FF ;20 DMA length count high										HHHHHHHH
DC.B \$00 ;21 DMA source address low										LLLLLLLL
DC.B \$00 ;22 DMA source address mid										MMMMMMMM
DC.B \$80 ;23 DMA source address high (C=CMD)							CCHHHHHH
VDPSettingsEnd:
even
```
Output:
Screenshot of emulator

## AArch64 Assembly

Works with: as version Raspberry Pi 3B version Buster 64 bits
```/* ARM assembly AARCH64 Raspberry PI 3B */
/*  program puzzle15_64.s   */

/*******************************************/
/* Constantes file                         */
/*******************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeConstantesARM64.inc"

.equ NBBOX,  16
.equ GRAINE,  123456      // change for other game
.equ NBSHUFFLE, 4
.equ KEYSIZE,  8

.equ IOCTL,     0x1D  // Linux syscall
.equ SIGACTION, 0x86   // Linux syscall
.equ SYSPOLL,   0x16  // Linux syscall
.equ CREATPOLL, 0x14  // Linux syscall
.equ CTLPOLL,   0x15  // Linux syscall

.equ TCGETS,    0x5401
.equ TCSETS,    0x5402
.equ ICANON,    2
.equ ECHO,     10
.equ POLLIN,    1

.equ SIGINT,   2    // Issued if the user sends an interrupt signal (Ctrl + C)
.equ SIGQUIT,  3    // Issued if the user sends a quit signal (Ctrl + D)
.equ SIGTERM, 15    // Software termination signal (sent by kill by default)
.equ SIGTTOU, 22    //

/*******************************************/
/* Structures                               */
/********************************************/
/* structure termios see doc linux*/
.struct  0
term_c_iflag:                    // input modes
.struct  term_c_iflag + 4
term_c_oflag:                    // output modes
.struct  term_c_oflag + 4
term_c_cflag:                    // control modes
.struct  term_c_cflag + 4
term_c_lflag:                    // local modes
.struct  term_c_lflag + 4
term_c_cc:                       // special characters
.struct  term_c_cc + 20      // see length if necessary
term_fin:

/* structure sigaction see doc linux */
.struct  0
sa_handler:
.struct  sa_handler + 8
sa_flags:
.struct  sa_flags + 8
sa_sigaction:
.struct  sa_sigaction + 8
sa_fin:

/* structure poll see doc linux */
.struct  0
poll_event:
.struct  poll_event + 8
poll_fd:                            //   File Descriptor
.struct  poll_fd + 8
poll_fin:
/*********************************/
/* Initialized data              */
/*********************************/
.data
sMessResult:           .ascii " "
sMessValeur:           .fill 11, 1, ' '             // size => 11
szCarriageReturn:      .asciz "\n"
szMessGameWin:         .asciz "You win in @ move number !!!!\n"
szMessMoveError:       .asciz "Huh... Impossible move !!!!\n"
szMessErreur:          .asciz "Error detected.\n"
szMessErrInitTerm:     .asciz "Error terminal init.\n"
szMessErrInitPoll:     .asciz "Error poll init.\n"
szMessSpaces:          .asciz "    "
szMessErr:             .asciz    "Error code hexa : @ décimal : @ \n"

szClear:     .byte 0x1B
.byte 'c'                         // console clear
.byte 0
/*********************************/
/* UnInitialized data            */
/*********************************/
.bss
.align 4
sZoneConv:      .skip 24
qCodeError:     .skip 8
ibox:           .skip 4 * NBBOX                // game boxes
qEnd:           .skip 8                        // 0 loop  1 = end loop
qTouche:        .skip KEYSIZE                  // value key pressed
stOldtio:       .skip term_fin                 // old terminal state
stCurtio:       .skip term_fin                 // current terminal state
stSigAction:    .skip sa_fin                   // area signal structure
stSigAction1:   .skip sa_fin
stSigAction2:   .skip sa_fin
stSigAction3:   .skip sa_fin
stPoll1:        .skip poll_fin                 // area poll structure
stPoll2:        .skip poll_fin
stevents:       .skip 16
/*********************************/
/*  code section                 */
/*********************************/
.text
.global main
main:                                // entry of program
mov x0,#0
bl initTerm                      // terminal init
cmp x0,0                         // error ?
blt 100f
bl initPoll                      // epoll instance init
cmp x0,0
blt 99f
mov x22,x0                       // save epfd
mov x9,#0                        // init counter
mov x0,0
1:                                   // loop init boxs
str w1,[x2,x0, lsl #2]           // store value
cmp x0,#NBBOX - 2                // end ?
ble 1b
mov x10,#15                      // empty box location
bl shuffleGame
2:                                   // loop moves
bl displayGame
3:
mov x0,x22                       // epfd
bl waitKey
cmp x0,0
beq 3b                           // no ket pressed -> loop
blt 99f                          // error ?
cmp x0,#-1
beq 99f                          // error
cmp x0,3                         // <ctrl_C>
beq 5f
cmp x0,113                       // saisie q (quit) ?
beq 5f
cmp x0,81                        // saisie Q  (Quit)?
beq 5f
mov x1,x0                        // key
bl keyMove                       // analyze key move
bl gameOK                        // end game ?
cmp x0,#1
bne 2b                           // no -> loop
// win
mov x0,x9                        // move counter
bl conversion10
bl strInsertAtCharInc            // insert result at @ character
bl affichageMess
5:
bl restauTerm                    // terminal restaur
mov x0, #0                       // return code
b 100f
99:
bl restauTerm                    // terminal restaur
mov x0,1                         // return code error
b 100f
100:                                 // standard end of the program
mov x8, #EXIT                    // request to exit program
svc #0                           // perform the system call

/******************************************************************/
/*     key move                                                   */
/******************************************************************/
/* x0 contains boxs address           */
/* x1 contains key value               */
/* x9 move counter                     */
/* x10 contains location empty box    */
keyMove:
stp x1,lr,[sp,-16]!              // save  registers
mov x7,x0
lsr x1,x1,16
cmp x1,#0x42                     // down arrow
bne 1f
cmp x10,#4                       // if x10 < 4   error
blt 80f
sub x2,x10,#4                    // compute location
b 90f
1:
cmp x1,#0x41                     // high arrow
bne 2f
cmp x10,#11                      // if x10 > 11   error
bgt 80f
b 90f
2:
cmp x1,#0x43                     // right arrow
bne 3f
tst x10,#0b11                    // if x10 = 0,4,8,12   error
beq 80f
sub x2,x10,#1                    // compute location
b 90f
3:
cmp x1,#0x44                     // left arrow
bne 100f
and x3,x10,#0b11                 // error if x10 = 3 7 11 and 15
cmp x3,#3
beq 80f
b 90f

80:                                  // move error
mov x1,#1
str x1,[x0]
b 100f
90:                                  // white box and move box inversion
ldr w3,[x7,x2,lsl #2]
str w3,[x7,x10,lsl #2]
mov x10,x2
mov x3,#0
str w3,[x7,x10,lsl #2]
add x9,x9,#1                        // increment move counter
100:
ldp x1,lr,[sp],16              // restaur  2 registers
/******************************************************************/
/*     shuffle game                                       */
/******************************************************************/
/* x0 contains boxs address           */
shuffleGame:
stp x1,lr,[sp,-16]!            // save  registers
stp x2,x3,[sp,-16]!            // save  registers
stp x4,x5,[sp,-16]!            // save  registers
mov x1,x0
mov x0,NBSHUFFLE
bl genereraleas
lsl x4,x0,#1
1:
mov x0,#14
bl genereraleas
mov x0,#14
bl genereraleas
ldr w2,[x1,x3,lsl #2]
ldr w0,[x1,x5,lsl #2]
str w2,[x1,x5,lsl #2]
str w0,[x1,x3,lsl #2]
subs x4,x4,#1
bgt 1b

100:
ldp x4,x5,[sp],16              // restaur  2 registers
ldp x2,x3,[sp],16              // restaur  2 registers
ldp x1,lr,[sp],16              // restaur  2 registers
/******************************************************************/
/*     game Ok ?                                      */
/******************************************************************/
/* x0 contains boxs address           */
gameOK:
stp x1,lr,[sp,-16]!            // save  registers
stp x2,x3,[sp,-16]!            // save  registers
mov x2,#0
ldr w3,[x0,x2,lsl #2]
1:
ldr w1,[x0,x2,lsl #2]
cmp w1,w3
bge 2f
mov x0,#0                      // game not Ok
b 100f
2:
mov x3,x1
cmp x2,#NBBOX -2
ble 1b
mov x0,#1                      // game Ok

100:
ldp x2,x3,[sp],16              // restaur  2 registers
ldp x1,lr,[sp],16              // restaur  2 registers
/******************************************************************/
/*     display game                                       */
/******************************************************************/
/* x0 contains boxs address           */
displayGame:
stp x1,lr,[sp,-16]!            // save  registers
// clear screen !
mov x4,x0
bl affichageMess
mov x2,#0
1:
ldr w0,[x4,x2,lsl #2]
cmp w0,#0
bne 2f
ldr w0,iSpaces                    // store spaces
str w0,[x1]
b 3f
2:
bl conversion10                     // call conversion decimal
cmp x0,1
beq 21f
mov x0,0x20
strh w0,[x1,#2]
b 3f
21:
mov w0,0x2020
str w0,[x1,#1]
3:
bl affichageMess                    // display message
tst x0,#0b11
bne 4f
bl affichageMess                    // display message
4:
cmp x2,#NBBOX - 1
ble 1b
bl affichageMess                    // display line return
ldr x0,qAdrqCodeError               // error detected ?
ldr x1,[x0]
cmp x1,#0
beq 100f
mov x1,#0                           // raz error code
str x1,[x0]
ldr x0,qAdrszMessMoveError          // display error message
bl affichageMess
100:
ldp x1,lr,[sp],16                   // restaur  2 registers
iSpaces:              .int 0x00202020   // spaces

/***************************************************/
/*   Generation random number                  */
/***************************************************/
/* x0 contains limit  */
genereraleas:
stp x1,lr,[sp,-16]!            // save  registers
stp x2,x3,[sp,-16]!            // save  registers
ldr x2,[x1]
ldr x3,qNbDep1
mul x2,x3,x2
ldr x3,qNbDep2
str x2,[x1]                    // maj de la graine pour l appel suivant
cmp x0,#0
beq 100f
udiv x3,x2,x0
msub x0,x3,x0,x2               // résult = remainder

100:                               // end function
ldp x2,x3,[sp],16              // restaur  2 registers
ldp x1,lr,[sp],16              // restaur  2 registers
/*****************************************************/

/******************************************************************/
/*     traitement du signal                                       */
/******************************************************************/
sighandler:
stp x0,lr,[sp,-16]!            // save  registers
str x1,[sp,-16]!
mov x1,#1                      // maj zone end
str x1,[x0]
ldr x1,[sp],16
ldp x0,lr,[sp],16              // restaur  2 registers
/***************************************************/
/*   display error message                         */
/***************************************************/
/* x0 contains error code  x1 : message address */
displayError:
stp x2,lr,[sp,-16]!            // save  registers
mov x2,x0                      // save error code
mov x0,x1
bl affichageMess
mov x0,x2                      // error code
bl conversion16                // conversion hexa
ldr x0,qAdrszMessErr           // display error message
bl strInsertAtCharInc               // insert result at @ character
mov x3,x0
mov x0,x2                      // error code
bl conversion10S                // conversion decimale
mov x0,x3
bl strInsertAtCharInc               // insert result at @ character
bl affichageMess
100:
ldp x2,lr,[sp],16              // restaur  2 registers
/*********************************/
/* init terminal state            */
/*********************************/
initTerm:
stp x1,lr,[sp,-16]!            // save  registers
mov x0,STDIN                   // input console
mov x1,TCGETS
mov x8,IOCTL                   // call system Linux
svc 0
cbnz x0,98f                    // error ?

str x0,[x1,sa_handler]         // maj handler
mov x0,SIGINT                  // signal type
mov x2,0
mov x3,8
mov x8,SIGACTION               // call system
svc 0

cmp x0,0                       // error ?
bne 98f
mov x0,SIGQUIT
mov x2,0                       // NULL
mov x8,SIGACTION               // call system
svc 0
cmp x0,0                       // error ?
bne 98f
mov x0,SIGTERM
mov x2,0                       // NULL
mov x8,SIGACTION               // appel systeme
svc 0
cmp x0,0
bne 98f
//
str x0,[x1,sa_handler]
mov x0,SIGTTOU                 //invalidate other process signal
mov x2,0                       // NULL
mov x8,SIGACTION               // call system
svc 0
cmp x0,0
bne 98f
//
/* read terminal current state  */
mov x0,STDIN
mov x1,TCGETS
mov x8,IOCTL                   // call systeme
svc 0
cmp x0,0                       // error ?
bne 98f
mov x2,ICANON | ECHO           // no key pressed echo on display
mvn x2,x2                      // and one key
ldr x3,[x1,#term_c_lflag]
str x3,[x1,#term_c_lflag]      // and store
mov x0,STDIN                   // maj terminal current state
mov x1,TCSETS
mov x8,IOCTL                   // call system
svc 0
cbz x0,100f
98:                                // error display
bl   displayError
mov x0,-1
100:
ldp x1,lr,[sp],16              // restaur  2 registers
/*********************************/
/* init instance epool            */
/*********************************/
initPoll:
stp x1,lr,[sp,-16]!            // save  registers
mov x1,STDIN                   // maj structure events
str x1,[x0,#poll_fd]           // maj FD
mov x1,POLLIN                  // action code
str x1,[x0,#poll_event]
mov x0,0
mov x8,CREATPOLL               // create epoll instance
svc 0
cmp x0,0                       // error ?
ble 98f
mov x10,x0                     // return FD epoll instance
mov x2,STDIN                   // Fd to we want add
mov x8,CTLPOLL                 // call system control epoll
svc 0
cmp x0,0                       // error ?
blt 98f                       // no
mov x0,x10                     // return FD epoll instance
b 100f
98:                                // error display
bl   displayError
mov x0,-1
100:
ldp x1,lr,[sp],16              // restaur  2 registers
/*********************************/
/* wait key                      */
/*********************************/
/* x0 contains FD poll    */
waitKey:
stp x1,lr,[sp,-16]!            // save  registers
str xzr,[x11]                  // raz key
1:
ldr x1,qAdrqEnd                // if signal ctrl-c  -> end
ldr x1,[x1]
cbnz x1,100f

mov x2,12                      // size events
mov x3,1                       // timeout = 1  TODO: ??
mov x4,0
mov x8,SYSPOLL                 // call system wait POLL
svc 0
cmp x0,0                       // key pressed ?
bge 100f
98:                                // error display
bl   displayError
mov x0,-1
100:
ldp x1,lr,[sp],16              // restaur  2 registers
/*********************************/
/*********************************/
/* x0 returns key value */
stp x1,lr,[sp,-16]!            // save  registers
mov x0,STDIN                   // File Descriptor
mov x2,KEYSIZE                 // key size
svc #0
cmp x0,0                       // error ?
ble 98f
ldr x0,[x2]
b 100f
98:                                // error display
bl   displayError
mov x0,-1
100:
ldp x1,lr,[sp],16              // restaur  2 registers
/*********************************/
/* restaur terminal state        */
/*********************************/
restauTerm:
stp x1,lr,[sp,-16]!            // save  registers
mov x0,STDIN                   // end then restaur begin state terminal
mov x1,TCSETS
mov x8,IOCTL                   // call system
svc 0
cbz x0,100f
bl   displayError
100:
ldp x1,lr,[sp],16              // restaur  2 registers

/********************************************************/
/*        File Include fonctions                        */
/********************************************************/
/* for this file see task include a file in language AArch64 assembly */
.include "../includeARM64.inc"```

## Action!

```DEFINE BOARDSIZE="16"
DEFINE X0="13"
DEFINE Y0="6"
DEFINE ITEMW="3"
DEFINE ITEMH="2"

BYTE ARRAY board(BOARDSIZE)
BYTE emptyX,emptyY,solved,first=[1]

BYTE FUNC Index(BYTE x,y)
RETURN (x+y*4)

PROC UpdateItem(BYTE x,y)
BYTE item

Position(X0+x*ITEMW+1,Y0+y*ITEMH+1)
item=board(Index(x,y))
IF item=0 THEN
Print("  ")
ELSEIF item<10 THEN
Put(160) Put(item+176)
ELSE
Put(item/10+176)
Put(item MOD 10+176)
FI
RETURN

PROC UpdateBoard()
BYTE x,y

FOR y=0 TO 3
DO
FOR x=0 TO 3
DO
UpdateItem(x,y)
OD
OD
RETURN

PROC DrawGrid()
CHAR ARRAY
top=[13 17 18 18 23 18 18 23 18 18 23 18 18 5],
row=[13 124 32 32 124 32 32 124 32 32 124 32 32 124],
mid=[13 1 18 18 19 18 18 19 18 18 19 18 18 4],
bot=[13 26 18 18 24 18 18 24 18 18 24 18 18 3]
BYTE y,i

y=Y0
Position(X0,y) Print(top) y==+1
Position(X0,y) Print(row) y==+1
FOR i=0 TO 2
DO
Position(X0,y) Print(mid) y==+1
Position(X0,y) Print(row) y==+1
OD
Position(X0,y) Print(bot)
RETURN

PROC DrawBoard()
DrawGrid()
UpdateBoard()
RETURN

PROC FindEmpty()
BYTE i

FOR i=0 TO BOARDSIZE-1
DO
IF board(i)=0 THEN
emptyX=i MOD 4
emptyY=i/4
FI
OD
RETURN

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

Position(9,3) Print("Game status: ")
IF solved THEN
Print("SOLVED !")
IF first=0 THEN
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)
FI
first=0
ELSE
Print("Shuffled")
FI
RETURN

PROC InitBoard()
BYTE i

FOR i=1 TO BOARDSIZE
DO
board(i-1)=i MOD 16
OD
FindEmpty()
solved=1
RETURN

BYTE FUNC IsSolved()
BYTE i

FOR i=1 TO BOARDSIZE
DO
IF board(i-1)#i MOD 16 THEN
RETURN (0)
FI
OD
RETURN (1)

PROC CheckStatus()
BYTE tmp

tmp=IsSolved()
IF solved#tmp THEN
solved=tmp
FI
RETURN

PROC Swap(BYTE x1,y1,x2,y2)
BYTE tmp,i1,i2

i1=Index(x1,y1)
i2=Index(x2,y2)
tmp=board(i1)
board(i1)=board(i2)
board(i2)=tmp
UpdateItem(x1,y1)
UpdateItem(x2,y2)
CheckStatus()
RETURN

PROC Shuffle()
BYTE i,j,tmp

i=BOARDSIZE-1
WHILE i>0
DO
j=Rand(i)
tmp=board(i)
board(i)=board(j)
board(j)=tmp
i==-1
OD
FindEmpty()
UpdateBoard()
CheckStatus()
RETURN

PROC MoveLeft()
IF emptyX=0 THEN RETURN FI
Swap(emptyX,emptyY,emptyX-1,emptyY)
emptyX==-1
RETURN

PROC MoveRight()
IF emptyX=3 THEN RETURN FI
Swap(emptyX,emptyY,emptyX+1,emptyY)
emptyX==+1
RETURN

PROC MoveUp()
IF emptyY=0 THEN RETURN FI
Swap(emptyX,emptyY,emptyX,emptyY-1)
emptyY==-1
RETURN

PROC MoveDown()
IF emptyY=3 THEN RETURN FI
Swap(emptyX,emptyY,emptyX,emptyY+1)
emptyY==+1
RETURN

PROC Main()
BYTE k,lastStick=[255],currStick,
CH=\$02FC, ;Internal hardware value for last key pressed
CRSINH=\$02F0 ;Controls visibility of cursor

Graphics(0)
SetColor(2,0,2)
CRSINH=1 ;hide cursor
Position(10,18) Print("Joystick - move tiles")
Position(9,19) Print("Space bar - shuffle")
Position(15,20) Print("ESC - exit")
InitBoard()
DrawBoard()
DO
currStick=Stick(0)
IF currStick#lastStick THEN
IF currStick=11 THEN MoveRight()
ELSEIF currStick=7 THEN MoveLeft()
ELSEIF currStick=13 THEN MoveUp()
ELSEIF currStick=14 THEN MoveDown()
FI
FI
lastStick=currStick
k=CH
IF k#\$FF THEN CH=\$FF FI
IF k=33 THEN Shuffle()
ELSEIF k=28 THEN EXIT
FI
OD
RETURN```
Output:

We fist define a generic package Generic_Puzzle. Upon instantiation, it can take any number of rows, any number of columns for a rows*columns-1 game. Instead of plain numbers, the tiles on the board can have arbitrary names (but they should all be of the same length). The package user can request the name for the tile at a certain (row,column)-point, and the set of possible moves. The user can move the empty space up, down, left and right (if possible). If the user makes the attempt to perform an impossible move, a Constraint_Error is raised.

```generic
Rows, Cols: Positive;
with function Name(N: Natural) return String; -- with Pre => (N < Rows*Cols);
-- Name(0) shall return the name for the empty tile
package Generic_Puzzle is

subtype Row_Type is Positive range 1 .. Rows;
subtype Col_Type is Positive range 1 .. Cols;
type Moves is (Up, Down, Left, Right);
type Move_Arr is array(Moves) of Boolean;

function Get_Point(Row: Row_Type; Col: Col_Type) return String;
function Possible return Move_Arr;
procedure Move(The_Move: Moves);

end Generic_Puzzle;
```

The package implementation is as follows.

```package body Generic_Puzzle is

Field: array(Row_Type, Col_Type) of Natural;
Current_R: Row_Type := Rows;
Current_C: Col_Type := Cols;
-- invariant: Field(Current_R, Current_C=0)
-- and for all R, C: Field(R, C) < R*C
-- and for all (R, C) /= (RR, CC): Field(R, C) /= Field(RR, CC)

function Get_Point(Row: Row_Type; Col: Col_Type) return String is
(Name(Field(Row, Col)));

function Possible return Move_Arr is
(Up => Current_R > 1, Down => Current_R < Rows,
Left => Current_C > 1, Right => Current_C < Cols);

procedure Move(The_Move: Moves) is
Old_R: Row_Type; Old_C: Col_Type; N: Natural;
begin
if not Possible(The_Move) then
raise Constraint_Error with "attempt to make impossible move";
else
-- remember current row and column
Old_R := Current_R;
Old_C := Current_C;

-- move the virtual cursor to a new position
case The_Move is
when Up    => Current_R := Current_R - 1;
when Down  => Current_R := Current_R + 1;
when Left  => Current_C := Current_C - 1;
when Right => Current_C := Current_C + 1;
end case;

-- swap the tiles on the board
N := Field(Old_R, Old_C);
Field(Old_R, Old_C) := Field(Current_R, Current_C);
Field(Current_R, Current_C) := N;
end if;
end Move;

begin
declare   -- set field to its basic setting
N: Positive := 1;
begin
for R in Row_Type loop
for C in Col_Type loop
if (R /= Current_R) or else (C /= Current_C) then
Field(R, C) := N;
N := N + 1;
else
Field(R, C) := 0;
end if;
end loop;
end loop;
end;
end Generic_Puzzle;
```

The main program reads the level from the command line. A larger level implies a more difficult instance. The default level is 10, which is fairly simple. After randomizing the board, the user can move the tiles.

```with Generic_Puzzle, Ada.Text_IO,

procedure Puzzle_15 is

function Image(N: Natural) return String is
(if N=0 then "   " elsif N < 10 then " " & Integer'Image(N)
else Integer'Image(N));

package Puzzle is new Generic_Puzzle(Rows => 4, Cols => 4, Name => Image);

Rand_Gen: Rnd.Generator;

Level: Natural := (if Ada.Command_Line.Argument_Count = 0 then 10
Initial_Moves: Natural := (2**(Level/2) + 2**((1+Level)/2))/2;
Texts: constant array(Puzzle.Moves) of String(1..9) :=
("u,U,^,8: ", "d,D,v,2: ", "l,L,<,4: ", "r,R,>,6: ");
Move_Counter: Natural := 0;
Command: Character;

begin
-- randomize board
for I in 1 .. Initial_Moves loop
declare
M: Puzzle.Moves := Rnd.Random(Rand_Gen);
begin
if Puzzle.Possible(M) then
Puzzle.Move(M);
end if;
end;
end loop;

-- read command and perform move
loop
-- Print board
for R in Puzzle.Row_Type loop
for C in Puzzle.Col_Type loop
end loop;
end loop;
begin
case Command is
when 'u' | 'U' | '^' | '8' =>
when 'd' | 'D' | 'v' | '2' =>
when 'l' | 'L' | '<' | '4' =>
when 'r' | 'R' | '>' | '6' =>
when '!' =>
exit;
when others =>
raise Constraint_Error with "wrong input";
end case;
Move_Counter := Move_Counter + 1;
exception when Constraint_Error =>
for M in Puzzle.Moves loop
if Puzzle.Possible(M) then
Ada.Text_IO.Put(Texts(M) & Puzzle.Moves'Image(M) & "   ");
end if;
end loop;
end;
end loop;
end Puzzle_15;
```
Output:
```>./puzzle_15 4
1  2  3  4
5  6  7  8
9 14 10 11
13    15 12
8
Up!
1  2  3  4
5  6  7  8
9    10 11
13 14 15 12
6
Right!
1  2  3  4
5  6  7  8
9 10    11
13 14 15 12
5
Possible Moves and Commands:
u,U,^,8: UP   d,D,v,2: DOWN   l,L,<,4: LEFT   r,R,>,6: RIGHT   !: Quit
1  2  3  4
5  6  7  8
9 10    11
13 14 15 12
6
Right!
1  2  3  4
5  6  7  8
9 10 11
13 14 15 12
2
Down!
1  2  3  4
5  6  7  8
9 10 11 12
13 14 15
!
4 moves!```
For other puzzles, one must just the single line with the package instantiation. E.g., for an 8-puzzle, we would write the following.
```   package Puzzle is new Generic_Puzzle(Rows => 3, Cols => 3, Name => Image);
```

## Amazing Hopper

```#include <jambo.h>

#define FILATABLA            5
#define COLUMNATABLA         10
#define Imprimelamatriz      Gosub 'Pone la matriz'
#define Imprimelascasillas   Gosub 'Pone las casillas'
#define Imprimeelíndiceen(_X_,_Y_)  Set '_X_,_Y_',  Gosub 'Pone el índice'

Main
Set break

Void (casilla, índice, números)
Link gosub( Crea una casilla, Crea el índice, Crea la matriz de números )

Cls
x=4, y=4, Tok sep '""', Gosub 'Imprime escenario'

/* INICIA EL JUEGO */
SW = 1, GANADOR = 0
c=0, cero x=4, cero y=4

Loop
Let ( c:=Getch )
Switch ( c )
Case 'KRIGHT'  { #( y < 4 ) do{ ++y }, Exit }
Case 'KDOWN'   { #( x < 4 ) do{ ++x }, Exit }
Case 'KLEFT'   { #( y > 1 ) do{ --y }, Exit }
Case 'KUP'     { #( x > 1 ) do{ --x }, Exit }
Case 'KRETURN' { If ( Gosub 'Chequear si movimiento es válido' )
Gosub 'Mover las casillas'
End If
Exit
}
Case 'KESCAPE' { SW=0 }
End switch

Gosub 'Imprime escenario'
Break if ( Gosub 'Verificar puzzle resuelto' --- Backup to 'GANADOR' )
Back if 'SW' is not zero

/* FIN DEL JUEGO */
Locate (18,15), Printnl("LO RESOLVISTE!")
End If
Locate (19,1), Prnl
End

Subrutines

/* CHEQUEO DE MOVIMIENTO */

Define ( Verificar puzzle resuelto )
ret = 0
Clr all marks
Tnúmeros=números
Redim (Tnúmeros,0), N = 0, Let ( N := Length(Tnúmeros) Minus (1))
i=1
Iterator ( ++i, Less equal ( i, N ) And( Not(ret) ), \
Let ( ret := Bit xor(i, [i] Get 'Tnúmeros') ) )
Clr all marks
Clear 'Tnúmeros'

Return 'Not (ret); And( Equals(i, Plus one(N)) ) '

Define ( Chequear si movimiento es válido )
Return 'Only one ( Equals (x, cero x), Equals(y, cero y ) )'

Define ( Mover las casillas )
If ( Equals (y, cero y) )
If ( Less (x, cero x) )      // mueve hacia abajo
Loop for ( i = cero x, #( i >= x ) , --i )
If ( Greater ( i, 1 ) )
[{i} Minus(1), y] Get 'números', [i,y] Put 'números'
Else
[{i} Plus(1), y] Get 'números', [i,y] Put 'números'
End If
Next
Else                         // por defecto: mueve hacia arriba
Loop for ( i = cero x, #( i <= x ) , ++i )
If ( Less ( i, 4 ) )
[{i} Plus(1), y] Get 'números', [i,y] Put 'números'
Else
[i,y] Get 'números', [{i} Minus(1),y] Put 'números'
End If
Next
End If
[x,y] Set '0', Put 'números'
Set 'x', Move to 'cero x'
Else                           // por defecto: está en la misma fila
If ( Less ( y, cero y ) )   // mueve hacia la derecha
Loop for ( i = cero y, #( i >= y ) , --i )
If ( Greater ( i, 1) )
[x, {i} Minus(1)] Get 'números', [x,i] Put 'números'
Else
[x, y] Get 'números', [x, {i} Plus(1)] Put 'números'
End If
Next
Else                        // por defecto: mueve hacia la izquierda
Loop for ( i = cero y, #( i <= y ) , ++i )
If ( Less ( i, 4 ) )
[x, {i} Plus(1)] Get 'números', [x,i] Put 'números'
Else
[x,i] Get 'números', [x,{i} Minus(1)] Put 'números'
End If
Next
End If
[x,y] Set '0', Put 'números'
Set 'y', Move to 'cero y'
End If
Clr all marks
Return

/* DESPLIEGUE DE CUADRITOS Y NUMEROS */

Define ( Imprime escenario )
Imprime las casillas
Imprime el índice en 'x,y'
Imprime la matriz
Return

Define ( Pone la matriz )
i=4, col = COLUMNA TABLA, celda=""
Clr all marks
py=1
Loop
j=4, fil = FILA TABLA, px=1
Loop
Locate 'Plus one(fil), Plus two (col)'
Printnl( Get if ([px,py] Get 'números' ---Backup to (celda)---, celda, "  ") )
fil += 3
--j, ++px
Back if (j) is not zero
col += 6, --i, ++py
Back if (i) is not zero
Return

Define ( Pone las casillas )
i=4, col = COLUMNA TABLA
Clr all marks
Loop
j=4, fil = FILA TABLA
Loop
Set 'fil, col', Gosub 'Pone un cuadrito'
fil += 3, --j
Back if (j) is not zero
col += 6, --i
Back if (i) is not zero
Return

Define (Pone un cuadrito, fil, col)
Locate 'fil, col', Print table 'casilla'
Return

Define ( Pone el índice, fil, col )
/* 5+(fil-1)*3 fila
10+(col-1)*6 col */
Clr all marks
Locate 'Minus one(fil) Mul by (3) Plus (FILA TABLA), Minus one(col) Mulby(6) Plus(COLUMNA TABLA)'
Print table 'índice'
Return

/* CONFIGURACION DEL JUEGO */

Define ( Crea la matriz de números )
Sequence ( 0, 1, 16, números )
Gosub 'Barajar el array'
Redim ( números, 4,4 )
Return

/* algoritmo de Fisher-Yates */
Define ( Barajar el array )
N = 0, Let ( N := Length(números) )
R = 0, aux = 0
Loop
Let (R := Ceil(Rand(N)))
Let (aux := [R] Get 'números' )
[N] Get 'números', [R] Put 'números'
Set 'aux', [N] Put 'números'
--N
Back if 'N' is positive
If ( [16] Get 'números' ---Backup to 'aux'---, Not (Is zero?) )
[aScan(1,0,números)] Set 'aux', Put 'números'
[16] Set '0', Put 'números'
End If
Return

Define ( Crea una casilla )
Set 'Utf8(Chr(218)),Utf8(Chr(196)),Utf8(Chr(196)),Utf8(Chr(196)),Utf8(Chr(196)),Utf8(Chr(191))', Apnd row 'casilla'
Set 'Utf8(Chr(179))," "," "," "," ",Utf8(Chr(179))', Apnd row 'casilla'
Set 'Utf8(Chr(192)),Utf8(Chr(196)),Utf8(Chr(196)),Utf8(Chr(196)),Utf8(Chr(196)),Utf8(Chr(217))', Apnd row 'casilla'
Return

Define ( Crea el índice )
Set 'Utf8(Chr(220)),Utf8(Chr(220)),Utf8(Chr(220)),Utf8(Chr(220)),Utf8(Chr(220)),Utf8(Chr(220))', Apnd row 'índice'
Set 'Utf8(Chr(219))," "," "," "," ",Utf8(Chr(219))', Apnd row 'índice'
Set 'Utf8(Chr(223)),Utf8(Chr(223)),Utf8(Chr(223)),Utf8(Chr(223)),Utf8(Chr(223)),Utf8(Chr(223))', Apnd row 'índice'
Return```
Output:
```\$ hopper jm/puzzle.jambo
┌────┐┌────┐┌────┐┌────┐
│ 14 ││ 5  ││ 3  ││ 12 │
└────┘└────┘└────┘└────┘
┌────┐┌────┐┌────┐┌────┐
│ 13 ││ 9  ││ 6  ││ 11 │
└────┘└────┘└────┘└────┘
┌────┐┌────┐┌────┐┌────┐
│ 15 ││ 10 ││ 8  ││ 2  │
└────┘└────┘└────┘└────┘
┌────┐┌────┐┌────┐▄▄▄▄▄▄
│ 4  ││ 1  ││ 7  │█    █
└────┘└────┘└────┘▀▀▀▀▀▀
..... (muchos click)
┌────┐┌────┐┌────┐┌────┐
│ 7  ││ 10 ││ 14 ││ 12 │
└────┘└────┘└────┘└────┘
┌────┐┌────┐┌────┐┌────┐
│ 15 ││    ││ 4  ││ 2  │
└────┘└────┘└────┘└────┘
┌────┐▄▄▄▄▄▄┌────┐┌────┐
│ 1  │█ 8  █│ 6  ││ 11 │
└────┘▀▀▀▀▀▀└────┘└────┘
┌────┐┌────┐┌────┐┌────┐
│ 3  ││ 13 ││ 5  ││ 9  │
└────┘└────┘└────┘└────┘
....( muy muchos clicks )
┌────┐┌────┐┌────┐┌────┐
│ 1  ││ 2  ││ 3  ││ 4  │
└────┘└────┘└────┘└────┘
┌────┐┌────┐┌────┐┌────┐
│ 5  ││ 6  ││ 7  ││ 8  │
└────┘└────┘└────┘└────┘
┌────┐┌────┐┌────┐┌────┐
│ 9  ││ 10 ││ 11 ││ 12 │
└────┘└────┘└────┘└────┘
┌────┐┌────┐┌────┐▄▄▄▄▄▄
│ 13 ││ 14 ││ 15 │█    █
└────┘└────┘└────┘▀▀▀▀▀▀

LO RESOLVISTE!
```

## APL

Works with: Dyalog APL version 16.0
```fpg←{⎕IO←0
⍺←4 4
(s∨.<0)∨2≠⍴s←⍺:'invalid shape:'s
0≠⍴⍴⍵:'invalid shuffle count:'⍵
d←d,-d←↓2 2⍴3↑1
e←¯1+⍴c←'↑↓←→○'
b←w←s⍴w←1⌽⍳×/s
z←⊃{
z p←⍵
n←(?⍴p)⊃p←(p≡¨(⊂s)|p)/p←(d~p)+⊂z
b[z n]←b[n z]
-⍨\n z
}⍣⍵⊢(s-1)0
⎕←b
⍬{
b≡w:'win'
0=⍴⍺:⍞∇ ⍵
e=i←c⍳m←⊃⍺:'quit'
i>e:⍞∇ ⍵⊣⎕←'invalid direction:'m
n≢s|n←⍵+i⊃d:⍞∇ ⍵⊣'out of bounds:'m
b[⍵ n]←b[n ⍵]
⎕←(s×0≠⍴⍺)⍴b
(1↓⍺)∇ n
}z
}
```
Output:
```      fpg 10
1  3  0  4
5  2  6  8
9 10  7 12
13 14 11 15
←
1  0  3  4
5  2  6  8
9 10  7 12
13 14 11 15
↓
1  2  3  4
5  0  6  8
9 10  7 12
13 14 11 15
→
1  2  3  4
5  6  0  8
9 10  7 12
13 14 11 15
↓↓
1  2  3  4
5  6  7  8
9 10 11 12
13 14  0 15
→
1  2  3  4
5  6  7  8
9 10 11 12
13 14 15  0
win

2 5 fpg 2
1 2 3 0 4
6 7 8 9 5
→
1 2 3 4 0
6 7 8 9 5
↓
1 2 3 4 5
6 7 8 9 0
win
```

## ARM Assembly

Works with: as version Raspberry Pi
```/* ARM assembly Raspberry PI  */
/*  program puzzle15.s   */

/************************************/
/* Constantes                       */
/************************************/
.equ STDIN,  0     @ Linux input console
.equ STDOUT, 1     @ Linux output console
.equ EXIT,   1     @ Linux syscall
.equ READ,   3     @ Linux syscall
.equ WRITE,  4     @ Linux syscall

.equ IOCTL,     0x36  @ Linux syscall
.equ SIGACTION, 0x43  @ Linux syscall
.equ SYSPOLL,   0xA8  @ Linux syscall

.equ TCGETS,    0x5401
.equ TCSETS,    0x5402
.equ ICANON,    2
.equ ECHO,     10
.equ POLLIN,    1

.equ SIGINT,   2    @ Issued if the user sends an interrupt signal (Ctrl + C)
.equ SIGQUIT,  3    @ Issued if the user sends a quit signal (Ctrl + D)
.equ SIGTERM, 15    @ Software termination signal (sent by kill by default)
.equ SIGTTOU, 22    @

.equ NBBOX,  16
.equ TAILLEBUFFER,   10

/*******************************************/
/* Structures                               */
/********************************************/
/* structure termios see doc linux*/
.struct  0
term_c_iflag:                    @ input modes
.struct  term_c_iflag + 4
term_c_oflag:                    @ output modes
.struct  term_c_oflag + 4
term_c_cflag:                    @ control modes
.struct  term_c_cflag + 4
term_c_lflag:                    @ local modes
.struct  term_c_lflag + 4
term_c_cc:                       @ special characters
.struct  term_c_cc + 20      @ see length if necessary
term_fin:

/* structure sigaction see doc linux */
.struct  0
sa_handler:
.struct  sa_handler + 4
sa_flags:
.struct  sa_flags + 4
sa_sigaction:
.struct  sa_sigaction + 4
sa_fin:

/* structure poll see doc linux */
.struct  0
poll_fd:                            @   File Descriptor
.struct  poll_fd + 4
.struct  poll_events + 4
poll_revents:                       @ events returned
.struct  poll_revents + 4
poll_fin:
/*********************************/
/* Initialized data              */
/*********************************/
.data
sMessResult:           .ascii " "
sMessValeur:           .fill 11, 1, ' '             @ size => 11
szCarriageReturn:      .asciz "\n"
szMessGameWin:         .ascii "You win in "
sMessCounter:           .fill 11, 1, ' '            @ size => 11
.asciz " move number !!!!\n"
szMessMoveError:       .asciz "Huh... Impossible move !!!!\n"
szMessErreur:          .asciz "Error detected.\n"
szMessSpaces:          .asciz "    "
iGraine:               .int 123456
/*************************************************/
szMessErr: .ascii	"Error code hexa : "
sHexa: .space 9,' '
.ascii "  decimal :  "
sDeci: .space 15,' '
.asciz "\n"
szClear:     .byte 0x1B
.byte 'c'                         @ console clear
.byte 0
/*********************************/
/* UnInitialized data            */
/*********************************/
.bss
.align 4
iCodeError:     .skip 4
ibox:          .skip 4 * NBBOX                 @ game boxes
iEnd:           .skip 4                        @ 0 loop  1 = end loop
iTouche:        .skip 4                        @ value key pressed
stOldtio:       .skip term_fin                 @ old terminal state
stCurtio:       .skip term_fin                 @ current terminal state
stSigAction:    .skip sa_fin                   @ area signal structure
stSigAction1:   .skip sa_fin
stPoll1:        .skip poll_fin                 @ area poll structure
stPoll2:        .skip poll_fin
/*********************************/
/*  code section                 */
/*********************************/
.text
.global main
main:                                @ entry of program
mov r0,#0
mov r9,#0                        @ move counter
1:                                   @ loop init boxs
str r1,[r2,r0, lsl #2]           @ store value
cmp r0,#NBBOX - 2                @ end ?
ble 1b
mov r10,#15                      @ empty box location
bl shuffleGame
2:                                   @ loop moves
bl displayGame
//bl gameOK                      @ end game ?
//cmp r0,#1
//beq 50f
cmp r0,#-1
beq 100f                         @ error or control-c
mov r1,r0                        @ key
bl keyMove
bl gameOK                        @ end game ?
cmp r0,#1
bne 2b                           @ no -> loop
50:                                  @ win
mov r0,r9                        @ move counter
bl conversion10
bl affichageMess

100:                                 @ standard end of the program
mov r0, #0                       @ return code
mov r7, #EXIT                    @ request to exit program
svc #0                           @ perform the system call

/******************************************************************/
/*     key move                                                   */
/******************************************************************/
/* r0 contains boxs address           */
/* r1 contains key value               */
/* r9 move counter                     */
/* r10 contains location empty box    */
keyMove:
push {r1-r8,lr}                  @ save  registers
mov r8,r0
cmp r1,#0x42                     @ down arrow
bne 1f
cmp r10,#4                       @ if r10 < 4   error
blt 80f
sub r2,r10,#4                    @ compute location
b 90f
1:
cmp r1,#0x41                     @ high arrow
bne 2f
cmp r10,#11                      @ if r10 > 11   error
bgt 80f
b 90f
2:
cmp r1,#0x43                     @ right arrow
bne 3f
tst r10,#0b11                    @ if r10 = 0,4,8,12   error
beq 80f
sub r2,r10,#1                    @ compute location
b 90f
3:
cmp r1,#0x44                     @ left arrow
bne 100f
and r3,r10,#0b11                 @ error if r10 = 3 7 11 and 15
cmp r3,#3
beq 80f
b 90f

80:                                  @ move error
mov r1,#1
str r1,[r0]
b 100f
90:                                  @ white box and move box inversion
ldr r3,[r8,r2,lsl #2]
str r3,[r8,r10,lsl #2]
mov r10,r2
mov r3,#0
str r3,[r8,r10,lsl #2]
add r9,#1                        @ increment move counter
100:
pop {r1-r8,lr}                   @ restaur registers
bx lr                            @return
/******************************************************************/
/*     shuffle game                                       */
/******************************************************************/
/* r0 contains boxs address           */
shuffleGame:
push {r1-r6,lr}                     @ save  registers
mov r1,r0
mov r0,#4
bl genereraleas
lsl r4,r0,#1
mov r0,r8
1:
mov r0,#14
bl genereraleas
mov r0,#14
bl genereraleas
ldr r2,[r1,r6,lsl #2]
ldr r3,[r1,r5,lsl #2]
str r2,[r1,r5,lsl #2]
str r3,[r1,r6,lsl #2]
subs r4,#1
bgt 1b

100:
pop {r1-r6,lr}                      @ restaur registers
bx lr                               @return
/******************************************************************/
/*     game Ok ?                                      */
/******************************************************************/
/* r0 contains boxs address           */
gameOK:
push {r1-r8,lr}                     @ save  registers
mov r8,r0
mov r2,#0
ldr r3,[r8,r2,lsl #2]
1:
ldr r4,[r8,r2,lsl #2]
cmp r4,r3
movlt r0,#0                         @ game mot Ok
blt 100f
mov r3,r4
cmp r2,#NBBOX -2
ble 1b
mov r0,#1                           @ game Ok

100:
pop {r1-r8,lr}                      @ restaur registers
bx lr                               @return
/******************************************************************/
/*     display game                                       */
/******************************************************************/
/* r0 contains boxs address           */
displayGame:
push {r1-r5,lr}                     @ save  registers
@ clear !
mov r4,r0
bl affichageMess
mov r2,#0
1:
ldr r0,[r4,r2,lsl #2]
cmp r0,#0
ldreq r0,iSpaces                    @ store spaces
streq r0,[r1]
beq 2f
bl conversion10                     @ call conversion decimal
mov r0,#0
strb r0,[r1,#3]                     @ zéro final
2:

bl affichageMess                    @ display message
tst r0,#0b11
bne 3f
bl affichageMess                    @ display message
3:
cmp r2,#NBBOX - 1
ble 1b
bl affichageMess                    @ display line return
ldr r0,iAdriCodeError               @ error detected ?
ldr r1,[r0]
cmp r1,#0
beq 100f
mov r1,#0                           @ raz error code
str r1,[r0]
ldr r0,iAdrszMessMoveError          @ display error message
bl affichageMess
100:
pop {r1-r5,lr}                      @ restaur registers
bx lr                               @return
iSpaces:                       .int 0x00202020       @ spaces
/******************************************************************/
/*     display text with size calculation                         */
/******************************************************************/
/* r0 contains the address of the message */
affichageMess:
push {r0,r1,r2,r7,lr}                          @ save  registres
mov r2,#0                                      @ counter length
1:                                                 @ loop length calculation
ldrb r1,[r0,r2]                                @ read octet start position + index
cmp r1,#0                                      @ if 0 its over
bne 1b                                         @ and loop
@ so here r2 contains the length of the message
mov r1,r0                                      @ address message in r1
mov r0,#STDOUT                                 @ code to write to the standard output Linux
mov r7, #WRITE                                 @ code call system "write"
svc #0                                         @ call systeme
pop {r0,r1,r2,r7,lr}                           @ restaur des  2 registres */
bx lr                                          @ return
/******************************************************************/
/*     Converting a register to a decimal unsigned                */
/******************************************************************/
/* r0 contains value and r1 address area   */
/* r0 return size of result (no zero final in area) */
/* area size => 11 bytes          */
.equ LGZONECAL,   10
conversion10:
push {r1-r4,lr}                                 @ save registers
mov r3,r1
mov r2,#LGZONECAL
1:                                                  @ start loop
bl divisionpar10U                               @ unsigned  r0 <- dividende. quotient ->r0 reste -> r1
strb r1,[r3,r2]                                 @ store digit on area
cmp r0,#0                                       @ stop if quotient = 0
subne r2,#1                                     @ else previous position
bne 1b                                          @ and loop
@ and move digit from left of area
mov r4,#0
2:
ldrb r1,[r3,r2]
strb r1,[r3,r4]
cmp r2,#LGZONECAL
ble 2b
@ and move spaces in end on area
mov r0,r4                                         @ result length
mov r1,#' '                                       @ space
3:
strb r1,[r3,r4]                                   @ store space in area
cmp r4,#LGZONECAL
ble 3b                                            @ loop if r4 <= area size

100:
pop {r1-r4,lr}                                    @ restaur registres
bx lr                                             @return

/***************************************************/
/*   division par 10   unsigned                    */
/***************************************************/
/* r0 dividende   */
/* r0 quotient    */
/* r1 remainder   */
divisionpar10U:
push {r2,r3,r4, lr}
mov r4,r0                                          @ save value
ldr r3,iMagicNumber                                @ r3 <- magic_number    raspberry 1 2
umull r1, r2, r3, r0                               @ r1<- Lower32Bits(r1*r0) r2<- Upper32Bits(r1*r0)
mov r0, r2, LSR #3                                 @ r2 <- r2 >> shift 3
add r2,r0,r0, lsl #2                               @ r2 <- r0 * 5
sub r1,r4,r2, lsl #1                               @ r1 <- r4 - (r2 * 2)  = r4 - (r0 * 10)
pop {r2,r3,r4,lr}
bx lr                                              @ leave function
iMagicNumber:  	.int 0xCCCCCCCD
/***************************************************/
/*   Generation random number                  */
/***************************************************/
/* r0 contains limit  */
genereraleas:
push {r1-r4,lr}                                    @ save registers
ldr r2,[r4]
ldr r3,iNbDep1
mul r2,r3,r2
ldr r3,iNbDep1
str r2,[r4]                                        @ maj de la graine pour l appel suivant
cmp r0,#0
beq 100f
mov r1,r0                                          @ divisor
mov r0,r2                                          @ dividende
bl division
mov r0,r3                                          @ résult = remainder

100:                                                   @ end function
pop {r1-r4,lr}                                     @ restaur registers
bx lr                                              @ return
/*****************************************************/
iNbDep1: .int 0x343FD
iNbDep2: .int 0x269EC3
/***************************************************/
/* integer division unsigned                       */
/***************************************************/
division:
/* r0 contains dividend */
/* r1 contains divisor */
/* r2 returns quotient */
/* r3 returns remainder */
push {r4, lr}
mov r2, #0                                         @ init quotient
mov r3, #0                                         @ init remainder
mov r4, #32                                        @ init counter bits
b 2f
1:                                                     @ loop
movs r0, r0, LSL #1                                @ r0 <- r0 << 1 updating cpsr (sets C if 31st bit of r0 was 1)
adc r3, r3, r3                                     @ r3 <- r3 + r3 + C. This is equivalent to r3 ? (r3 << 1) + C
cmp r3, r1                                         @ compute r3 - r1 and update cpsr
subhs r3, r3, r1                                   @ if r3 >= r1 (C=1) then r3 <- r3 - r1
adc r2, r2, r2                                     @ r2 <- r2 + r2 + C. This is equivalent to r2 <- (r2 << 1) + C
2:
subs r4, r4, #1                                    @ r4 <- r4 - 1
bpl 1b                                             @ if r4 >= 0 (N=0) then loop
pop {r4, lr}
bx lr
/***************************************************/
/***************************************************/
push {r1-r7,lr}
mov r5,#0
mov r0,#STDIN                                @ input console
mov r1,#TCGETS
mov r7, #IOCTL                               @ call system Linux
svc #0
cmp r0,#0                                    @ error ?
beq 1f
bl   displayError
mov r0,#-1
b 100f
1:
str r0,[r1,#sa_handler]                      @ maj handler
mov r0,#SIGINT                               @ signal type
mov r2,#0                                    @ NULL
mov r7, #SIGACTION                           @ call system
svc #0
cmp r0,#0                                    @ error ?
bne 97f
mov r0,#SIGQUIT
mov r2,#0                                    @ NULL
mov r7, #SIGACTION                           @ call system
svc #0
cmp r0,#0                                    @ error ?
bne 97f
mov r0,#SIGTERM
mov r2,#0                                    @ NULL
mov r7, #SIGACTION                           @ appel systeme
svc #0
cmp r0,#0
bne 97f
@
str r0,[r1,#sa_handler]
mov r0,#SIGTTOU                              @invalidate other process signal
mov r2,#0                                    @ NULL
mov r7,#SIGACTION                            @ call system
svc #0
cmp r0,#0
bne 97f
@
/* read terminal current state  */
mov r0,#STDIN
mov r1,#TCGETS
mov r7,#IOCTL                                @ call systeme
svc #0
cmp r0,#0                                    @ error ?
bne 97f
mov r2,#ICANON | ECHO                        @ no key pressed echo on display
mvn r2,r2                                    @ and one key
ldr r3,[r1,#term_c_lflag]
str r3,[r1,#term_c_lflag]                    @ and store
mov r0,#STDIN                                @ maj terminal current state
mov r1,#TCSETS
mov r7, #IOCTL                               @ call system
svc #0
cmp r0,#0
bne 97f
@
2:                                               @ loop waiting key
ldr r0,iAdriEnd                              @ if signal ctrl-c  -> end
ldr r0,[r0]
cmp r0,#0
movne r5,#-1
bne 98f
mov r1,#STDIN
str r1,[r0,#poll_fd]                          @ maj FD
mov r1,#POLLIN                                @ action code
str r1,[r0,#poll_events]
mov r1,#1                                     @ items number structure poll
mov r2,#0                                     @ timeout = 0
mov r7,#SYSPOLL                               @ call system POLL
svc #0
cmp r0,#0                                     @ key pressed ?
ble 2b                                        @ no key pressed -> loop
mov r0,#STDIN                                 @ File Descriptor
mov r2,#TAILLEBUFFER                          @ buffer size
svc #0
cmp r0,#0                                     @ error ?
bgt 98f

97:                                               @ error detected
bl   displayError
mov r5,#-1
98:                                               @ end then restaur begin state terminal
mov r0,#STDIN
mov r1,#TCSETS
mov r7,#IOCTL                                 @ call system
svc #0
cmp r0,#0
beq 99f                                       @ restaur ok
bl   displayError
mov r0,#-1
b 100f
99:
cmp r5,#0                                     @ error or control-c
ldreqb r0,[r2,#2]                             @ return key byte
movne r0,r5                                   @ or error
100:
pop {r1-r7, lr}
bx lr
iSIG_IGN:                 .int 1
/******************************************************************/
/*     traitement du signal                                       */
/******************************************************************/
sighandler:
push {r0,r1}
mov r1,#1                 @ maj zone end
str r1,[r0]
pop {r0,r1}
bx lr
/***************************************************/
/*   display error message                         */
/***************************************************/
/* r0 contains error code  r1 : message address */
displayError:
push {r0-r2,lr}                         @ save registers
mov r2,r0                               @ save error code
mov r0,r1
bl affichageMess
mov r0,r2                               @ error code
bl conversion16                         @ conversion hexa
mov r0,r2                               @ error code
bl conversion10                         @ conversion decimale
ldr r0,iAdrszMessErr                    @ display error message
bl affichageMess
100:
pop {r0-r2,lr}                          @ restaur registers
bx lr                                   @ return
/******************************************************************/
/*     Converting a register to hexadecimal                      */
/******************************************************************/
/* r0 contains value and r1 address area   */
conversion16:
push {r1-r4,lr}                                    @ save registers
mov r2,#28                                         @ start bit position
mov r3,r0                                          @ save entry value
1:                                                     @ start loop
and r0,r3,r4                                       @value register and mask
lsr r0,r2                                          @ move right
cmp r0,#10                                         @ compare value
addge r0,#55                                       @ >10  ->letter A-F
strb r0,[r1],#1                                    @ store digit on area and + 1 in area address
lsr r4,#4                                          @ shift mask 4 positions
subs r2,#4                                         @  counter bits - 4 <= zero  ?
bge 1b                                             @  no -> loop

100:
pop {r1-r4,lr}                                     @ restaur registers
bx lr                                              @return```

## Arturo

```;; ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~
;; ===>> ~~ Game's functions ~~ <<===
;; --->> ~~ Init functions ~~ <<---

;; This is a solved sample that is used to
;; init and finish the game
solvedTable: @[ "  1  " "  2  " "  3  " "  4  "
"  5  " "  6  " "  7  " "  8  "
"  9  " "  10 " "  11 " "  12 "
"  13 " "  14 " "  15 " "     " ]

;; Use this once in :game's init, to get a player position
;; Q: Why use it once?
;; A: This algorithm is slower than just get a stored varible
;; yet this searches for a string for every value from :game
getPlayerPosition: \$[table :block][
return index table "     "
]

;; This is the object that represents the game
;; 'table » The sample table to generate the game
define :game [
table :block
][

init: [
; checks if 'table has 16 elements
ensure [16 = size this\table]

;; The game's table itself
this\table: (shuffle this\table) ; creates a random game
;; The current movement. When less, better is your punctuation
this\movements: 0
;; The current 'playerPosition in table
;; Used to evaluate if certain movement is possible or not
this\playerPosition: getPlayerPosition this\table
;; Defines it the gameLoop still running
this\running?: true
]

;; A builtin print function that simplifies the use
print: [
render {
Movements: |this\movements|, Position: |this\playerPosition|
*-----*-----*-----*-----*
|this\table\0| |this\table\1| |this\table\2| |this\table\3|
*-----*-----*-----*-----*
|this\table\4| |this\table\5| |this\table\6| |this\table\7|
*-----*-----*-----*-----*
|this\table\8| |this\table\9| |this\table\10| |this\table\11|
*-----*-----*-----*-----*
|this\table\12| |this\table\13| |this\table\14| |this\table\15|
*-----*-----*-----*-----*
}
]

;; Compares the internal's 'table with another :block
compare: [
if this\table = that
-> return true
]

]

;; These are the commands used internally on game
;; To avoid ambiguity, User's input'll to be translated to this
gameActions: ['up, 'left, 'down, 'right, 'quit]

;; ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~
;; -->> Print funnctions <<---

;; A template for print instructions
printInstructions: [
color #cyan "Type (WASD) to move and (Q) to quit."
]

;; A template for print input warning
;; 'input: the wrong input itself that will be printed
printWrongInput: \$[inp :string][
print color #red
~"Wrong input: '|inp|'"
]

;; A template for print input warning
;; 'action: could be 'up, 'down, 'left or 'right
printWrongMovement: \$[action :literal][
print color #red
~"Wrong movement. Can't go |action|"
]

;; ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~
;; --->> Validators/Checkers functions <<---

;; Checks if a 'input is in 'gameActions
;; Valids for: 'up, 'down, 'left, 'right and 'quit
validInput?: \$[inp :any][
return (in? inp gameActions)
]

;; Checks if the current movement tried is possible
;; 'game » is the current game
;; 'movement » must be in 'gameActions, but can't be 'quit
validMovement?: \$[
game     :game
movement :literal
][
pos: game\playerPosition
case [movement]
when? [='up]
-> return (not? in? pos [0..3])
when? [='down]
-> return (not? in? pos [12..15])
when? [='left]
-> return (not? in? pos [0 4 8 12])
when? [='right]
-> return (not? in? pos [3 7 11 15])
else
-> return false
]

;; ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~
;; --->> Action functions <<---

;; Gets user input from terminal
;; returning a :literal from 'gameActions
;; Raises: In case of wrong input,
;; will be returned the same input as a :string
parseInput: \$[inp :string][
lowerInp: lower inp
case [lowerInp]
when? [="w"] -> return 'up
when? [="a"] -> return 'left
when? [="s"] -> return 'down
when? [="d"] -> return 'right
when? [="q"] -> return 'quit
else -> return inp
]

;; Moves the player in Game's Table
;; Note that this's a unsafe function,
;; use 'validMovement? to check a 'movement given a game,
;; and then use this
movePlayer: \$[
game     :game
movement :literal
][

position: game\playerPosition

updateGame: \$[
game             :game
playerPosition   :integer
relativePosition :integer
][
try [

; 'otherPosition is the real index of the 'relativePosition
otherPosition: + playerPosition relativePosition

; -- Updates the table, swaping the positions
temp: game\table\[playerPosition]
game\table\[playerPosition]: game\table\[otherPosition]
game\table\[otherPosition]: temp

game\playerPosition: otherPosition
game\movements: inc game\movements
] else -> panic "'movement didn't checked."
]

case [movement]
when? [='up]
-> (updateGame game position (neg 4))
when? [='down]
-> (updateGame game position (4))
when? [='left]
-> (updateGame game position (neg 1))
when? [='right]
-> (updateGame game position (1))
else -> panic "'movement didn't checked."

]

endGame: \$[
message :string
][
print message
exit
]

;; ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~
;; --->> Run function <<---

;; Inits ans runs the game
;; 'sampleTable must be already solved
runGame: \$[sampleTable :block][
game: to :game [sampleTable]

while [game\running?] [
print game
print printInstructions
command: parseInput input ">> "

if command = 'quit
-> endGame "Exiting game..."

validInp: validInput? command
if? validInp [
validMov: validMovement? game command
(validMov)?
-> movePlayer game command
-> printWrongMovement command
] else
-> printWrongInput command

if sampleTable = game
-> endGame "Congratulations! You won!"
print ""
]
]

runGame solvedTable```

## Astro

```type Puzzle(var items: {}, var position: -1)

fun mainframe(puz):
let d = puz.items
print('+-----+-----+-----+-----+')
print(d[1], d[2], d[3], d[4], first: '|', sep: '|', last: '|')
print('+-----+-----+-----+-----+')
print(d[5], d[6], d[7], d[8], first: '|', sep: '|', last: '|')
print('+-----+-----+-----+-----+')
print(d[9], d[10], d[11], d[12], first: '|', sep: '|', last: '|')
print('+-----+-----+-----+-----+')
print(d[13], d[14], d[15], d[16], first: '|', sep: '|', last: '|')
print('+-----+-----+-----+-----+')

fun format(puz, ch):
match ch.trim().length:
1 => '  \$ch  '
2 => '  \$ch '
0 => '     '

fun change(puz, to):
let fro = puz.position
for a, b in puz.items where b == puz.format(str i):
to = a
break

swap(puz.items[fro], :[to])
puz.position = to;

fun buildboard(puz, difficulty):
for i in 1..16:
puz.items[i] = puz.format(str i)

var tmp = a
for a, b in puz.items where b == '  16 ':
puz.items[a] = '     '
tmp = a
break

puz.position = tmp
let diff = match difficulty:
0 => 10
1 => 50
_ => 100

for i in 1..diff:
let lst = puz.validmoves()
let lst1 = []
for j in lst:
lst1.push! j.trim().int()
puz.change(lst1[random(1, lst1.length - 1)])

fun validmoves(puz):
match puz.position:
6 | 7 | 10 | 11 =>
puz.items[pos - 4], :[pos - 1], :[pos + 1], :[pos + 4]
5 | 9 =>
puz.items[pos - 4], :[pos + 4], :[pos + 1]
8 | 12 =>
puz.items[pos - 4], :[pos + 4], :[pos - 1]
2 | 3 =>
puz.items[pos - 1], :[pos + 1], :[pos + 4]
14 | 15 =>
puz.items[pos - 1], :[pos + 1], :[pos - 4]
1 =>
puz.items[pos + 1], :[pos + 4]
4 =>
puz.items[pos - 1], :[pos + 4]
13 =>
puz.items[pos + 1], :[pos - 4]
16 =>
puz.items[pos - 1], :[pos - 4]

fun mainframe(puz):
var flag = false
for a, b in puz.items:
if b == '     ':
pass
else:
flag = (a == b.trim().int())
..
return flag

let game = Puzzle()
game.buildboard(
int(input('Enter the difficulty : 0 1 2\n2 => highest 0=> lowest\n'))
)
game.mainframe()

print 'Enter 0 to exit'

loop:
print 'Hello user:\nTo change the position just enter the no. near it'

var lst = game.validmoves()
var lst1 = []
for i in lst:
lst1.push! i.trim().int()
print(i.strip(), '\t', last: '')

print()

let value = int(input())
if value == 0:
break
elif x not in lst1:
print('Wrong move')
else:
game.change(x)

game.mainframe()
if g.gameover():
print 'You WON'
break
```

## AutoHotkey

```Size := 20
Grid := [], Deltas := ["-1,0","1,0","0,-1","0,1"], Width := Size * 2.5
Gui, font, S%Size%
loop, 4
{
Row := A_Index
loop, 4
{
Col := A_Index
Gui, add, button, % (Col=1 ? "xs y+1" : "x+1 yp") " v" Row "_" Col " w" Width " gButton -TabStop", % Grid[Row,Col] := Col + (Row-1)*4 ; 1-16
}
}
GuiControl, Hide, % Row "_" Col	; 4_4
Gui, add, Button, % "xs gShuffle w" 4 * Width + 3, Shuffle
Gui, show,, 15 Puzzle
return
;------------------------------
GuiClose:
ExitApp
return
;------------------------------
Shuffle:
Shuffle := true
loop, 1000
{
Random, Rnd, 1,4
Move(StrSplit(Deltas[Rnd], ",").1, StrSplit(Deltas[Rnd], ",").2)
}
Shuffle := false
return
;------------------------------
Button:
buttonRow := SubStr(A_GuiControl, 1, 1), ButtonCol := SubStr(A_GuiControl, 3, 1)
if Abs(buttonRow-Row) > 1 || Abs(ButtonCol-Col) > 1 || Abs(buttonRow-Row) = Abs(ButtonCol-Col)
return
Move(buttonRow-Row, ButtonCol-Col)
return
;------------------------------
#IfWinActive, 15 Puzzle
;------------------------------
Down::
Move(-1, 0)
return
;------------------------------
Up::
Move(1, 0)
return
;------------------------------
Right::
Move(0, -1)
return
;------------------------------
Left::
Move(0, 1)
return
;------------------------------
#IfWinActive
;------------------------------
Move(deltaRow, deltaCol){
global
if (Row+deltaRow=0) || (Row+deltaRow=5) || (Col+deltaCol=0) || (Col+deltaCol=5)
return
GuiControl, Hide, % Row+deltaRow "_" Col+deltaCol
GuiControl, Show, % Row "_" Col
GuiControl,, %Row%_%Col%, % Grid[Row+deltaRow, Col+deltaCol]
Grid[Row, Col] := Grid[Row+deltaRow, Col+deltaCol]
Grid[Row+=deltaRow, Col+=deltaCol] := 16
if Shuffle
return
gridCont := ""
for m, obj in grid
for n, val in obj
gridCont .= val ","
if (Trim(gridCont, ",") = "1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16")
MsgBox, 262208, 15 Puzzle, You solved 15 Puzzle
}
```

## BASIC

### Commodore BASIC

```10 REM 15-PUZZLE GAME
20 REM COMMODORE BASIC 2.0
30 REM ********************************
40 GOSUB 400 : REM INTRO AND LEVEL
50 GOSUB 510 : REM SETUP BOARD
60 GOSUB 210 : REM PRINT PUZZLE
70 PRINT "TO MOVE A PIECE, ENTER ITS NUMBER:"
80 INPUT X
90 GOSUB 760 : REM CHECK IF MOVE IS VALID
100 IF MV=0 THEN PRINT "WRONG MOVE" : GOSUB 1130 : GOTO 60
110 D(Z)=X : D(Y)=0
120 GOSUB 210 : REM PRINT PUZZLE
130 GOSUB 1030: REM CHECK IF PUZZLE COMPLETE
140 IF PC THEN 160
150 GOTO 70
160 PRINT"YOU WON!"
170 END
180 REM
190 REM *******************************
200 REM PRINT/DRAW THE PUZZLE
210 FOR P=1 TO 16
220   IF D(P)=0 THEN D\$(P)="     " : GOTO 260
230   S\$=STR\$(D(P))
240   N=LEN(S\$)
250   D\$(P) = LEFT\$("   ",3-N)+S\$+"  "
260 NEXT
270 PRINT "+-----+-----+-----+-----+"
280 PRINT "!"D\$(1)"!"D\$(2)"!"D\$(3)"!"D\$(4)"!"
290 PRINT "+-----+-----+-----+-----+"
300 PRINT "!"D\$(5)"!"D\$(6)"!"D\$(7)"!"D\$(8)"!"
310 PRINT "+-----+-----+-----+-----+"
320 PRINT "!"D\$(9)"!"D\$(10)"!"D\$(11)"!"D\$(12)"!"
330 PRINT "+-----+-----+-----+-----+"
340 PRINT "!"D\$(13)"!"D\$(14)"!"D\$(15)"!"D\$(16)"!"
350 PRINT "+-----+-----+-----+-----+"
360 RETURN
370 REM
380 REM *******************************
390 REM INTRO AND LEVEL OF DIFFICULTY
400 PRINT CHR\$(147)
410 DIM SH(3) : SH(1)=10 : SH(2)=50 : SH(3)=100
420 PRINT "15 PUZZLE GAME FOR COMMODORE BASIC 2.0" : PRINT : PRINT
430 PRINT "PLEASE ENTER LEVEL OF DIFFICULTY,"
440 PRINT "1(EASY), 2(MEDIUM) OR 3(HARD):";
450 INPUT V
460 IF V<1 OR V>3 THEN 440
470 RETURN
480 REM
490 REM *******************************
500 REM BUILD THE BOARD
510 DIM D(16) : DIM D\$(16) : REM BOARD PIECES
520 REM SET PIECES IN CORRECT ORDER FIRST
530 FOR P=1 TO 15
540   D(P) = P
550 NEXT
560 D(16) = 0 : REM 0 = EMPTY PIECE/SLOT
570 Z=16      : REM Z = EMPTY POSITION
580 PRINT: PRINT "SHUFFLING PIECES";
590 FOR N=1 TO SH(V)
600   PRINT".";
610   X = INT(RND(0)*4)+1
620   IF X=1 THEN R=Z-4
630   IF X=2 THEN R=Z+4
640   IF (X=3) AND (INT((Z-1)/4)<>(Z-1)/4) THEN R=Z-1
650   IF (X=4) AND (INT(Z/4)<>Z/4) THEN R=Z+1
660   IF R<1 OR R>16 THEN 610
670   D(Z)=D(R)
680   Z=R
690   D(Z)=0
700 NEXT
710 PRINT CHR\$(147)
720 RETURN
730 REM
740 REM *******************************
750 REM CHECK IF MOVE IS VALID
760 MV = 0
770 IF X<1 OR X>15 THEN RETURN
780 REM FIND POSITION OF PIECE X AND OF EMPTY PIECE
790 AX=X
800 GOSUB 940 : REM FIND POSITION OF PIECE AX
810 Y=P
820 AX=0
830 GOSUB 940 : REM FIND POSITION OF PIECE AX
840 Z=P
850 REM CHECK IF EMPTY PIECE IS ABOVE, BELOW, LEFT OR RIGHT TO PIECE X
860 IF Y-4=Z THEN MV=1 : RETURN
870 IF Y+4=Z THEN MV=1 : RETURN
880 IF (Y-1=Z) AND (INT(Z/4)<>Z/4) THEN MV=1 : RETURN
890 IF (Y+1=Z) AND (INT(Y/4)<>Y/4) THEN MV=1 : RETURN
900 RETURN
910 REM
920 REM *******************************
930 REM FIND POSITION OF PIECE AX
940 P=1
950 IF D(P)=AX THEN 990
960   P=P+1
970   IF P>16 THEN PRINT "UH OH!" : STOP
980 GOTO 950
990 RETURN
1000 REM
1010 REM *******************************
1020 REM CHECK IF PUZZLE IS COMPLETE / GAME OVER
1030 PC = 0
1040 P=1
1050 IF (P>=16) OR (D(P)<>P) THEN 1080
1060   P=P+1
1070 GOTO 1050
1080 IF P=16 THEN PC=1
1090 RETURN
1100 REM
1110 REM ******************************
1120 REM A SMALL DELAY
1130 FOR T=0 TO 400
1140 NEXT
1150 RETURN
```

## BBC BASIC

Works with: ARM BBC BASIC
Works with: Brandy BASIC version Matrix Brandy
```      IF INKEY(-256)=77 OR (INKEY(-256) AND &F0)=&A0 THEN MODE 1: COLOUR 0: COLOUR 143: *FX4,1

SIZE=4 : DIFFICULTY=3

MAX=SIZE * SIZE - 1
DIM Board(MAX)
FOR I%=1 TO MAX : Board(I% - 1)=I% : NEXT
Gap=MAX
WHILE N% < DIFFICULTY ^ 2 PROCSlide(RND(4)) : ENDWHILE : REM Shuffle
N%=0

@%=2 + LOG(MAX + 1)
PROCShowAndTest
WHILE NOT Solved
PRINT "Use arrow keys to move the gap around. Moves taken: ";N%
PROCSlide(GET - 135)
PROCShowAndTest
ENDWHILE
PRINT "Solved after ";N% LEFT\$(" moves", 6 + (N% = 1)) "."
END

DEF PROCSlide(dir%)
NewGap=Gap
CASE dir% OF
WHEN 1: IF Gap MOD SIZE > 0        NewGap=Gap - 1    : N%+=1 : REM Left
WHEN 2: IF Gap MOD SIZE < SIZE - 1 NewGap=Gap + 1    : N%+=1 : REM Right
WHEN 3: IF Gap < MAX - SIZE + 1    NewGap=Gap + SIZE : N%+=1 : REM Down
WHEN 4: IF Gap > SIZE - 1          NewGap=Gap - SIZE : N%+=1 : REM Up
ENDCASE
SWAP Board(Gap), Board(NewGap)
Gap=NewGap
ENDPROC

DEF PROCShowAndTest
CLS
Solved=TRUE
FOR I%=0 TO MAX
COLOUR 12 : COLOUR 135
IF I% = Gap COLOUR 1 : COLOUR 129
IF I% MOD SIZE = SIZE - 1 PRINT Board(I%) ELSE PRINT Board(I%),;
IF Solved IF I% < MAX - 1 IF Board(I%) > Board(I% + 1) OR I% = Gap Solved=FALSE
NEXT
COLOUR 0 : COLOUR 143
PRINT
ENDPROC
```

## BQN

Translation of: APL
```_while_ ← {𝔽⍟𝔾∘𝔽_𝕣_𝔾∘𝔽⍟𝔾𝕩}
FPG←{
𝕊𝕩: 4‿4𝕊𝕩;
(∧´𝕨<0)∨2≠≠𝕨 ? •Out "Invalid shape: "∾•Fmt 𝕨;
0≠=𝕩 ? •Out "Invalid shuffle count: "∾•Fmt 𝕩;
s𝕊𝕩:
d←⟨1‿0⋄¯1‿0⋄0‿1⋄0‿¯1⟩ # Directions
w←𝕨⥊1⌽↕×´𝕨 # Solved grid
b←w        # Board
z←⊑{
z‿p←𝕩
p↩(⊢≡s⊸|)¨⊸/(<z)+d(¬∘∊/⊣)p # filter out invalid
n←(•rand.Range ≠p)⊑p
b⌽⌾(z‿n⊸⊑)↩ # switch places
-`n‿z
}⍟𝕩 ⟨𝕨-1,⟨0⟩⟩
{
𝕊:
b≡w ? •Show b, •Out "You win", 0;
•Show b
inp←⊑{
Check 𝕩:
•Out "Enter move: "
x←•GetLine@
i←⊑"↑↓←→q"⊐x
{
i=4 ? i; # quit
i>4 ? •Out "Invalid direction: "∾x, Check x;
(⊢≢s⊸|)z+i⊑d ? •Out "Out of bounds: "∾x, Check x;
i
}
} @
{
𝕩=4 ? •Out "Quitting", 0;
mv←z+𝕩⊑d
b⌽⌾(mv‿z⊸⊑)↩
z↩mv
1
} inp
} _while_ ⊢ 1
@
}```
```   )ex 15_puzzle.bqn
FPG 10
┌─
╵  1  2  0  3
5  6  7  4
9 10 11  8
13 14 15 12
┘
Enter move:
a
Invalid direction: a
Enter move:
↑
┌─
╵  1  2  7  3
5  6  0  4
9 10 11  8
13 14 15 12
┘
Enter move:
↓
┌─
╵  1  2  0  3
5  6  7  4
9 10 11  8
13 14 15 12
┘
Enter move:
↓
Out of bounds: ↓
...```

## C

### C89, 22 lines version

The task, as you can see, can be resolved in 22 lines of no more than 80 characters. Of course, the source code in C is not very readable. The second example works exactly the same way, but it was written in much more human readable way. The program also works correctly for non-standard number of rows and/or columns.

```/* RosettaCode: Fifteen puzle game, C89, plain vanillia TTY, MVC, § 22 */
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 4
#define M 4
enum Move{UP,DOWN,LEFT,RIGHT};int hR;int hC;int cc[N][M];const int nS=100;int
update(enum Move m){const int dx[]={0,0,-1,1};const int dy[]={-1,1,0,0};int i=hR
+dy[m];int j=hC+dx[m];if(i>= 0&&i<N&&j>=0&&j<M){cc[hR][hC]=cc[i][j];cc[i][j]=0;
hR=i;hC=j;return 1;}return 0;}void setup(void){int i,j,k;for(i=0;i<N;i++)for(j=0
;j<M;j++)cc[i][j]=i*M+j+1;cc[N-1][M-1]=0;hR=N-1;hC=M-1;k=0;while(k<nS)k+=update(
(enum Move)(rand()%4));}int isEnd(void){int i,j; int k=1;for(i=0;i<N;i++)for(j=0
;j<M;j++)if((k<N*M)&&(cc[i][j]!=k++))return 0;return 1;}void show(){int i,j;
putchar('\n');for(i=0;i<N;i++)for(j=0;j<M;j++){if(cc[i][j])printf(j!=M-1?" %2d "
:" %2d \n",cc[i][j]);else printf(j!=M-1?" %2s ":" %2s \n", "");}putchar('\n');}
void disp(char* s){printf("\n%s\n", s);}enum Move get(void){int c;for(;;){printf
("%s","enter u/d/l/r : ");c=getchar();while(getchar()!='\n');switch(c){case 27:
exit(0);case'd':return UP;case'u':return DOWN;case'r':return LEFT;case'l':return
RIGHT;}}}void pause(void){getchar();}int main(void){srand((unsigned)time(NULL));
do setup();while(isEnd());show();while(!isEnd()){update(get());show();}disp(
"You win"); pause();return 0;}
```

### C89, short version, TTY mode

```/*
* RosettaCode: Fifteen puzle game, C89, plain vanillia TTY, MVC
*/

#define _CRT_SECURE_NO_WARNINGS /* unlocks printf etc. in MSVC */
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

enum Move { MOVE_UP = 0, MOVE_DOWN = 1, MOVE_LEFT = 2, MOVE_RIGHT = 3 };

/* *****************************************************************************
* Model
*/

#define NROWS     4
#define NCOLLUMNS 4
int holeRow;
int holeCollumn;
int cells[NROWS][NCOLLUMNS];
const int nShuffles = 100;

int Game_update(enum Move move){
const int dx[] = {  0,  0, -1, +1 };
const int dy[] = { -1, +1,  0,  0 };
int i = holeRow     + dy[move];
int j = holeCollumn + dx[move];
if ( i >= 0 && i < NROWS && j >= 0 && j < NCOLLUMNS ){
cells[holeRow][holeCollumn] = cells[i][j];
cells[i][j] = 0; holeRow = i; holeCollumn = j;
return 1;
}
return 0;
}

void Game_setup(void){
int i,j,k;
for ( i = 0; i < NROWS; i++ )
for ( j = 0; j < NCOLLUMNS; j++ )
cells[i][j] = i * NCOLLUMNS + j + 1;
cells[NROWS-1][NCOLLUMNS-1] = 0;
holeRow = NROWS - 1;
holeCollumn = NCOLLUMNS - 1;
k = 0;
while ( k < nShuffles )
k += Game_update((enum Move)(rand() % 4));
}

int Game_isFinished(void){
int i,j; int k = 1;
for ( i = 0; i < NROWS; i++ )
for ( j = 0; j < NCOLLUMNS; j++ )
if ( (k < NROWS*NCOLLUMNS) && (cells[i][j] != k++ ) )
return 0;
return 1;
}

/* *****************************************************************************
* View
*/

void View_showBoard(){
int i,j;
putchar('\n');
for ( i = 0; i < NROWS; i++ )
for ( j = 0; j < NCOLLUMNS; j++ ){
if ( cells[i][j] )
printf(j != NCOLLUMNS-1 ? " %2d " : " %2d \n", cells[i][j]);
else
printf(j != NCOLLUMNS-1 ? " %2s " : " %2s \n", "");
}
putchar('\n');
}

void View_displayMessage(char* text){
printf("\n%s\n", text);
}

/* *****************************************************************************
* Controller
*/

enum Move Controller_getMove(void){
int c;
for(;;){
printf("%s", "enter u/d/l/r : ");
c = getchar();
while( getchar() != '\n' )
;
switch ( c ){
case 27: exit(EXIT_SUCCESS);
case 'd' : return MOVE_UP;
case 'u' : return MOVE_DOWN;
case 'r' : return MOVE_LEFT;
case 'l' : return MOVE_RIGHT;
}
}
}

void Controller_pause(void){
getchar();
}

int main(void){

srand((unsigned)time(NULL));

do Game_setup(); while ( Game_isFinished() );

View_showBoard();
while( !Game_isFinished() ){
Game_update( Controller_getMove() );
View_showBoard();
}

View_displayMessage("You win");
Controller_pause();

return EXIT_SUCCESS;
}
```
Output:
```  9   1   4   7
6   5   3   2
13  10       8
14  15  11  12

enter u/d/l/r : u

9   1   4   7
6   5   3   2
13  10  11   8
14  15      12

enter u/d/l/r : l

9   1   4   7
6   5   3   2
13  10  11   8
14  15  12

enter u/d/l/r : d

9   1   4   7
6   5   3   2
13  10  11
14  15  12   8

enter u/d/l/r :```

### C89, long version, TTY/Winapi/ncurses modes

```/**
* RosettaCode: Fifteen puzle game, C89, MS Windows Console API, MVC
*
* @version 0.2 (added TTY and ncurses modes)
*/

#define UNDEFINED_WIN32API_CONSOLE
#define UNDEFINED_NCURSES_CONSOLE
#if !defined (TTY_CONSOLE) && !defined(WIN32API_CONSOLE) && !defined(NCURSES_CONSOLE)
#define TTY_CONSOLE
#endif

#define _CRT_SECURE_NO_WARNINGS    /* enable printf etc. */
#define _CRT_NONSTDC_NO_DEPRECATE  /* POSIX functions enabled */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#if defined(NCURSES_CONSOLE)
#include "curses.h"  /* see http://pdcurses.sourceforge.net/ */
#elif defined(WIN32API_CONSOLE)
#define NOGDI                   /* we don't need GDI */
#define WIN32_LEAN_AND_MEAN     /* we don't need OLE etc. */
#include <windows.h>            /* MS Windows stuff */
#include <conio.h>              /* kbhit() and getch() */
#endif

enum Move { MOVE_UP = 0, MOVE_DOWN = 1, MOVE_LEFT = 2, MOVE_RIGHT = 3 };

/* *****************************************************************************
* Model
*/

#define NROWS     4
#define NCOLLUMNS 4
int holeRow;
int holeCollumn;
int cells[NROWS][NCOLLUMNS];
const int nShuffles = 100;

int Game_update(enum Move move){
const int dx[] = {  0,  0, -1, +1 };
const int dy[] = { -1, +1,  0,  0 };
int i = holeRow     + dy[move];
int j = holeCollumn + dx[move];
if ( i >= 0 && i < NROWS && j >= 0 && j < NCOLLUMNS ){
cells[holeRow][holeCollumn] = cells[i][j];
cells[i][j] = 0; holeRow = i; holeCollumn = j;
return 1;
}
return 0;
}

void Game_setup(void){
int i,j,k;
for ( i = 0; i < NROWS; i++ )
for ( j = 0; j < NCOLLUMNS; j++ )
cells[i][j] = i * NCOLLUMNS + j + 1;
cells[NROWS-1][NCOLLUMNS-1] = 0;
holeRow = NROWS - 1;
holeCollumn = NCOLLUMNS - 1;
k = 0;
while ( k < nShuffles )
k += Game_update((enum Move)(rand() % 4));
}

int Game_isFinished(void){
int i,j; int k = 1;
for ( i = 0; i < NROWS; i++ )
for ( j = 0; j < NCOLLUMNS; j++ )
if ( (k < NROWS*NCOLLUMNS) && (cells[i][j] != k++ ) )
return 0;
return 1;
}

/* *****************************************************************************
* View
*/

int fieldWidth;
#ifdef WIN32API_CONSOLE
HANDLE hConsole;
CONSOLE_SCREEN_BUFFER_INFO csbi;
#endif

void View_setup_base(void)
{
int i;
fieldWidth = 0;
for ( i = NROWS * NCOLLUMNS - 1; i > 0; i /= 10 )
fieldWidth++;
}

#if defined(TTY_CONSOLE)

void View_setup(void) {
View_setup_base();
}

void View_showBoard()
{
int i,j;
putchar('\n');
for ( i = 0; i < NROWS; i++ )
for ( j = 0; j < NCOLLUMNS; j++ ){
if ( cells[i][j] )
printf(j != NCOLLUMNS-1 ? " %*d " : " %*d \n", fieldWidth, cells[i][j]);
else
printf(j != NCOLLUMNS-1 ? " %*s " : " %*s \n", fieldWidth, "");
}
putchar('\n');
}

void View_displayMessage(char* text)
{
printf("\n%s\n", text);
}

#elif defined(NCURSES_CONSOLE)

void View_setup(void) {
View_setup_base();
initscr();
clear();
}

void View_showBoard()
{
int i,j;
for ( i = 0; i < NROWS; i++ )
for ( j = 0; j < NCOLLUMNS; j++ ){
int x = (fieldWidth+1)*j;
int y = 2*i;
if ( cells[i][j] ){
attron(A_REVERSE);
mvprintw(y,x,"%*d", fieldWidth, cells[i][j]);
}else{
attroff(A_REVERSE);
mvprintw(y,x,"%*s", fieldWidth, " ");
}
}
attrset(A_NORMAL);
}

void View_displayMessage(char* text)
{
mvprintw(2*NROWS,0, "%s", text);
}

#elif defined(WIN32API_CONSOLE)

void View_setup(void) {
const COORD coordHome = { 0, 0 };
CONSOLE_CURSOR_INFO cci;
DWORD size, nWritten;
View_setup_base();
hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
cci.bVisible = FALSE;
cci.dwSize = 1;
SetConsoleCursorInfo(hConsole,&cci);
GetConsoleScreenBufferInfo(hConsole,&(csbi));
size = csbi.dwSize.X*csbi.dwSize.Y;
FillConsoleOutputCharacter(hConsole,' ',size,coordHome,&nWritten);
FillConsoleOutputAttribute(hConsole,csbi.wAttributes,size,coordHome,&nWritten);

}

void View_showBoard()
{
int i,j;
char labelString[32];
WORD attributes;
DWORD nWritten;
for ( i = 0; i < NROWS; i++ )
for ( j = 0; j < NCOLLUMNS; j++ ){
COORD coord = { ((SHORT)fieldWidth+1)*j, coord.Y = 2*i };
if ( cells[i][j] ){
sprintf(labelString,"%*d", fieldWidth, cells[i][j]);
attributes = BACKGROUND_BLUE | BACKGROUND_GREEN | BACKGROUND_RED;
}else{
sprintf(labelString,"%*s", fieldWidth, " ");
attributes = csbi.wAttributes;
}
WriteConsoleOutputCharacter(hConsole,labelString,fieldWidth,coord,&nWritten);
FillConsoleOutputAttribute (hConsole,attributes,fieldWidth,coord,&nWritten);
}
}

void View_displayMessage(char* text)
{
DWORD nWritten;
COORD coord = { 0, 2 * NROWS };
WriteConsoleOutputCharacter(hConsole,text,strlen(text),coord,&nWritten);
}

#endif

/* *****************************************************************************
* Controller
*/

#if defined(TTY_CONSOLE)

void Controller_setup(void){
}

enum Move Controller_getMove(void){
int c;
for(;;){
printf("%s", "enter u/d/l/r : ");
c = getchar();
while( getchar() != '\n' )
;
switch ( c ){
case 27: exit(EXIT_SUCCESS);
case 'd' : return MOVE_UP;
case 'u' : return MOVE_DOWN;
case 'r' : return MOVE_LEFT;
case 'l' : return MOVE_RIGHT;
}
}
}

void Controller_pause(void)
{
getchar();
}

#elif defined(NCURSES_CONSOLE)

void Controller_setup(void){
noecho();
cbreak();
curs_set(0);
}

enum Move Controller_getMove(void){
for(;;){
switch ( wgetch(stdscr) ){
case  27: exit(EXIT_SUCCESS);
case KEY_DOWN  : return MOVE_UP;
case KEY_UP    : return MOVE_DOWN;
case KEY_RIGHT : return MOVE_LEFT;
case KEY_LEFT  : return MOVE_RIGHT;
case ERR: /* NOP */;
}
}
}

void Controller_pause(void){
while ( wgetch(stdscr) == ERR )
;
}

#elif defined(WIN32API_CONSOLE)

void Controller_setup(void){
}

enum Move Controller_getMove(void){
for(;;){
switch ( getch() ){
case  27: exit(EXIT_SUCCESS);
case   0:
case 224: switch ( getch() ){
case 80 : return MOVE_UP;
case 72 : return MOVE_DOWN;
case 77 : return MOVE_LEFT;
case 75 : return MOVE_RIGHT;
}
}
}
}

void Controller_pause(void){
while(  kbhit() ) getch();
while( !kbhit() )   ;
while(  kbhit() ) getch();
}

#endif

/* *****************************************************************************
* Main function: create model, view and controller. Run main loop.
*/
int main(void) {

srand((unsigned)time(NULL));

do Game_setup(); while ( Game_isFinished() );
View_setup();
Controller_setup();

View_showBoard();
while( !Game_isFinished() ){
Game_update( Controller_getMove() );
View_showBoard();
}

View_displayMessage("You win");
Controller_pause();

return EXIT_SUCCESS;
}
```

## C#

Works with: C sharp version 3+
```using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;

public class FifteenPuzzle
{
const int GridSize = 4; //Standard 15 puzzle is 4x4
const int BlockCount = 16;

static readonly Random R = new Random();

private List<Button> Puzzles = new List<Button>();
private int Moves = 0;
private DateTime Start;

public class Puzzle
{
private int mOrderedNumer;

public int CurrentNumber;

public int X;
public int Y;

public int InvX
{
get { return (GridSize - 1) - X; }
}
public int InvY
{
get { return (GridSize - 1) - Y; }
}

public Puzzle(int OrderedNumer)
{
mOrderedNumer = OrderedNumer;

CurrentNumber = OrderedNumer;

X = OrderedNumer % GridSize;
Y = OrderedNumer / GridSize;
}
public Puzzle(int OrderedNumer, int CurrentNumber)
: this(OrderedNumer)
{
this.CurrentNumber = CurrentNumber;
}

public bool IsEmptyPuzzle
{
get { return CurrentNumber >= (BlockCount - 1); }
}
public bool IsTruePlace
{
get { return (CurrentNumber == mOrderedNumer); }
}
public bool NearestWith(Puzzle OtherPz)
{
int dx = (X - OtherPz.X);
int dy = (Y - OtherPz.Y);

if ((dx == 0) && (dy <= 1) && (dy >= -1)) return true;
if ((dy == 0) && (dx <= 1) && (dx >= -1)) return true;

return false;
}

public override string ToString()
{
return (CurrentNumber + 1).ToString();
}
}

public static void Main(string[] args)
{
FifteenPuzzle Game = new FifteenPuzzle();
Application.Run(Game.CreateForm());
}

private Form CreateForm()
{
int ButtonSize = 50;
int ButtonMargin = 3;
int FormEdge = 9;

Font ButtonFont = new Font("Arial", 15.75F, FontStyle.Regular);

Button StartButton = new Button();
StartButton.Location = new Point(FormEdge, (GridSize * (ButtonMargin + ButtonSize)) + FormEdge);
StartButton.Size = new Size(86, 23);
StartButton.Font = new Font("Arial", 9.75F, FontStyle.Regular);
StartButton.Text = "New Game";
StartButton.UseVisualStyleBackColor = true;
StartButton.TabStop = false;

StartButton.Click += new EventHandler(NewGame);

int FormWidth = (GridSize * ButtonSize) + ((GridSize - 1) * ButtonMargin) + (FormEdge * 2);
int FormHeigth = FormWidth + StartButton.Height;

Form Form = new Form();
Form.Text = "Fifteen";
Form.ClientSize = new Size(FormWidth, FormHeigth);
Form.FormBorderStyle = FormBorderStyle.FixedSingle;
Form.MaximizeBox = false;
Form.SuspendLayout();

for (int i = 0; i < BlockCount; i++)
{
Button Bt = new Button();
Puzzle Pz = new Puzzle(i);

int PosX = FormEdge + (Pz.X) * (ButtonSize + ButtonMargin);
int PosY = FormEdge + (Pz.Y) * (ButtonSize + ButtonMargin);
Bt.Location = new Point(PosX, PosY);

Bt.Size = new Size(ButtonSize, ButtonSize);
Bt.Font = ButtonFont;

Bt.Text = Pz.ToString();
Bt.Tag = Pz;
Bt.UseVisualStyleBackColor = true;
Bt.TabStop = false;

Bt.Enabled = false;
if (Pz.IsEmptyPuzzle) Bt.Visible = false;

Bt.Click += new EventHandler(MovePuzzle);

}

Form.ResumeLayout();

return Form;
}

private void NewGame(object Sender, EventArgs E)
{
do
{
for (int i = 0; i < Puzzles.Count; i++)
{
Button Bt1 = Puzzles[R.Next(i, Puzzles.Count)];
Button Bt2 = Puzzles[i];
Swap(Bt1, Bt2);
}
}
while (!IsSolvable());

for (int i = 0; i < Puzzles.Count; i++)
{
Puzzles[i].Enabled = true;
}

Moves = 0;
Start = DateTime.Now;
}

private void MovePuzzle(object Sender, EventArgs E)
{
Button Bt1 = (Button)Sender;
Puzzle Pz1 = (Puzzle)Bt1.Tag;

Button Bt2 = Puzzles.Find(Bt => ((Puzzle)Bt.Tag).IsEmptyPuzzle);
Puzzle Pz2 = (Puzzle)Bt2.Tag;

if (Pz1.NearestWith(Pz2))
{
Swap(Bt1, Bt2);
Moves++;
}

CheckWin();
}

private void CheckWin()
{
Button WrongPuzzle = Puzzles.Find(Bt => !((Puzzle)Bt.Tag).IsTruePlace);
bool UWin = (WrongPuzzle == null);

if (UWin)
{
for (int i = 0; i < Puzzles.Count; i++)
{
Puzzles[i].Enabled = false;
}

TimeSpan Elapsed = DateTime.Now - Start;
Elapsed = TimeSpan.FromSeconds(Math.Round(Elapsed.TotalSeconds, 0));
MessageBox.Show(String.Format("Solved in {0} moves. Time: {1}", Moves, Elapsed));
}
}

private void Swap(Button Bt1, Button Bt2)
{
if (Bt1 == Bt2) return;

Puzzle Pz1 = (Puzzle)Bt1.Tag;
Puzzle Pz2 = (Puzzle)Bt2.Tag;

int g = Pz1.CurrentNumber;
Pz1.CurrentNumber = Pz2.CurrentNumber;
Pz2.CurrentNumber = g;

Bt1.Visible = true;
Bt1.Text = Pz1.ToString();
if (Pz1.IsEmptyPuzzle) Bt1.Visible = false;

Bt2.Visible = true;
Bt2.Text = Pz2.ToString();
if (Pz2.IsEmptyPuzzle) Bt2.Visible = false;
}

private bool IsSolvable()
{
// WARNING: size of puzzle board MUST be even(like 4)!
// For explain see: https://www.geeksforgeeks.org/check-instance-15-puzzle-solvable/

int InvCount = 0;
for (int i = 0; i < Puzzles.Count - 1; i++)
{
for (int j = i + 1; j < Puzzles.Count; j++)
{
Puzzle Pz1 = (Puzzle)Puzzles[i].Tag;
if (Pz1.IsEmptyPuzzle) continue;

Puzzle Pz2 = (Puzzle)Puzzles[j].Tag;
if (Pz2.IsEmptyPuzzle) continue;

if (Pz1.CurrentNumber > Pz2.CurrentNumber) InvCount++;
}
}

Button EmptyBt = Puzzles.Find(Bt => ((Puzzle)Bt.Tag).IsEmptyPuzzle);
Puzzle EmptyPz = (Puzzle)EmptyBt.Tag;

bool Result = false;
if ((EmptyPz.InvY + 1) % 2 == 0) // is even
{
// is odd
if (InvCount % 2 != 0) Result = true;
}
else // is odd
{
// is even
if (InvCount % 2 == 0) Result = true;
}
return Result;
}
}
```

## C++

```#include <time.h>
#include <stdlib.h>
#include <vector>
#include <string>
#include <iostream>
class p15 {
public :
void play() {
bool p = true;
std::string a;
while( p ) {
createBrd();
while( !isDone() ) { drawBrd();getMove(); }
drawBrd();
std::cout << "\n\nCongratulations!\nPlay again (Y/N)?";
std::cin >> a; if( a != "Y" && a != "y" ) break;
}
}
private:
void createBrd() {
int i = 1; std::vector<int> v;
for( ; i < 16; i++ ) { brd[i - 1] = i; }
brd[15] = 0; x = y = 3;
for( i = 0; i < 1000; i++ ) {
getCandidates( v );
move( v[rand() % v.size()] );
v.clear();
}
}
void move( int d ) {
int t = x + y * 4;
switch( d ) {
case 1: y--; break;
case 2: x++; break;
case 4: y++; break;
case 8: x--;
}
brd[t] = brd[x + y * 4];
brd[x + y * 4] = 0;
}
void getCandidates( std::vector<int>& v ) {
if( x < 3 ) v.push_back( 2 ); if( x > 0 ) v.push_back( 8 );
if( y < 3 ) v.push_back( 4 ); if( y > 0 ) v.push_back( 1 );
}
void drawBrd() {
int r; std::cout << "\n\n";
for( int y = 0; y < 4; y++ ) {
std::cout << "+----+----+----+----+\n";
for( int x = 0; x < 4; x++ ) {
r = brd[x + y * 4];
std::cout << "| ";
if( r < 10 ) std::cout << " ";
if( !r ) std::cout << "  ";
else std::cout << r << " ";
}
std::cout << "|\n";
}
std::cout << "+----+----+----+----+\n";
}
void getMove() {
std::vector<int> v; getCandidates( v );
std::vector<int> p; getTiles( p, v ); unsigned int i;
while( true ) {
std::cout << "\nPossible moves: ";
for( i = 0; i < p.size(); i++ ) std::cout << p[i] << " ";
int z; std::cin >> z;
for( i = 0; i < p.size(); i++ )
if( z == p[i] ) { move( v[i] ); return; }
}
}
void getTiles( std::vector<int>& p, std::vector<int>& v ) {
for( unsigned int t = 0; t < v.size(); t++ ) {
int xx = x, yy = y;
switch( v[t] ) {
case 1: yy--; break;
case 2: xx++; break;
case 4: yy++; break;
case 8: xx--;
}
p.push_back( brd[xx + yy * 4] );
}
}
bool isDone() {
for( int i = 0; i < 15; i++ ) {
if( brd[i] != i + 1 ) return false;
}
return true;
}
int brd[16], x, y;
};
int main( int argc, char* argv[] ) {
srand( ( unsigned )time( 0 ) );
p15 p; p.play(); return 0;
}
```
```+----+----+----+----+
| 11 |  5 | 12 |  3 |
+----+----+----+----+
| 10 |  7 |  6 |  4 |
+----+----+----+----+
| 13 |    |  2 |  1 |
+----+----+----+----+
| 15 | 14 |  8 |  9 |
+----+----+----+----+

Possible moves: 2 13 14 7
```

## COBOL

Tested with GnuCOBOL

```         >>SOURCE FORMAT FREE
*> This code is dedicated to the public domain
*> This is GNUCOBOL 2.0
identification division.
program-id. fifteen.
environment division.
configuration section.
repository. function all intrinsic.
data division.
working-storage section.

01  r pic 9.
01  r-empty pic 9.
01  r-to pic 9.
01  r-from pic 9.

01  c pic 9.
01  c-empty pic 9.
01  c-to pic 9.
01  c-from pic 9.

01  display-table.
03  display-row occurs 4.
05  display-cell occurs 4 pic 99.

01  tile-number pic 99.
01  tile-flags pic x(16).

01  display-move value spaces.
03  tile-id pic 99.

01  row-separator pic x(21) value all '.'.
01  column-separator pic x(3) value ' . '.

01  inversions pic 99.
01  current-tile pic 99.

01  winning-display pic x(32) value
'01020304'
&   '05060708'
&   '09101112'
&   '13141500'.

procedure division.
start-fifteen.
display 'start fifteen puzzle'
display '    enter a two-digit tile number and press <enter> to move'
display '    press <enter> only to exit'

*> tables with an odd number of inversions are not solvable
perform initialize-table with test after until inversions = 0
perform show-table
accept display-move
perform until display-move = spaces
perform move-tile
perform show-table
move spaces to display-move
accept display-move
end-perform
stop run
.
initialize-table.
compute tile-number = random(seconds-past-midnight) *> seed only
move spaces to tile-flags
move 0 to current-tile inversions
perform varying r from 1 by 1 until r > 4
after c from 1 by 1 until c > 4
perform with test after
until tile-flags(tile-number + 1:1) = space
compute tile-number = random() * 100
compute tile-number = mod(tile-number, 16)
end-perform
move 'x' to tile-flags(tile-number + 1:1)
if tile-number > 0 and < current-tile
end-if
move tile-number to display-cell(r,c) current-tile
end-perform
compute inversions = mod(inversions,2)
.
show-table.
if display-table = winning-display
display 'winning'
end-if
display space row-separator
perform varying r from 1 by 1 until r > 4
perform varying c from 1 by 1 until c > 4
if display-cell(r,c) = 00
display '  ' with no advancing
move r to r-empty
move c to c-empty
else
end-if
end-perform
display column-separator
end-perform
display space row-separator
.
move-tile.
if not (tile-id numeric and tile-id >= 01 and <= 15)
display 'invalid tile number'
exit paragraph
end-if

*> find the entered tile-id row and column (r,c)
perform varying r from 1 by 1 until r > 4
after c from 1 by 1 until c > 4
if display-cell(r,c) = tile-id
exit perform
end-if
end-perform

*> show-table filled (r-empty,c-empty)
evaluate true
when r = r-empty
if c-empty < c
*> shift left
perform varying c-to from c-empty by 1 until c-to > c
compute c-from = c-to + 1
move display-cell(r-empty,c-from) to display-cell(r-empty,c-to)
end-perform
else
*> shift right
perform varying c-to from c-empty by -1 until c-to < c
compute c-from = c-to - 1
move display-cell(r-empty,c-from) to display-cell(r-empty,c-to)
end-perform
end-if
move 00 to display-cell(r,c)
when c = c-empty
if r-empty < r
*>shift up
perform varying r-to from r-empty by 1 until r-to > r
compute r-from = r-to + 1
move display-cell(r-from,c-empty) to display-cell(r-to,c-empty)
end-perform
else
*> shift down
perform varying r-to from r-empty by -1 until r-to < r
compute r-from = r-to - 1
move display-cell(r-from,c-empty) to display-cell(r-to,c-empty)
end-perform
end-if
move 00 to display-cell(r,c)
when other
display 'invalid move'
end-evaluate
.
end program fifteen.
```
Output:
```prompt\$ cobc -xj fifteen.cbl
start fifteen puzzle
enter a two-digit tile number and press <enter> to move
press <enter> only to exit
.....................
. 05 . 14 . 08 . 12 .
. 01 . 10 . 03 . 09 .
. 02 . 15 . 13 . 11 .
. 06 .    . 07 . 04 .
.....................
```

## Common Lisp

Credit to this post for help with the inversions-counting function: [1]

```|15|::main
```
.
```(defpackage :15
(:use :common-lisp))
(in-package :15)

(defvar +side+ 4)
(defvar +max+ (1- (* +side+ +side+))) ; 15

(defun make-board ()
(make-array (list +side+ +side+)
:initial-contents
(loop :for i :below +side+ :collecting
(loop :for j :below +side+ :collecting
(mod (1+ (+ j (* i +side+))) (1+ +max+))))))
(defvar *board* (make-board))

(defun shuffle-board (board)
(loop for i from (array-total-size board) downto 2
do (rotatef (row-major-aref board (random i))
(row-major-aref board (1- i))))
board)

(defun pb (stream object &rest args)
(declare (ignorable args))
(loop for i below (car (array-dimensions object)) do
(loop for j below (cadr (array-dimensions object)) do
(let ((cell (aref object i j)))
(format stream "(~[  ~:;~:*~2d~])" cell)))
(format stream "~%")))

(defun sortedp (board)
(declare (ignorable board))
(loop for i upto +max+
when (eq (row-major-aref board i) (mod (1+ i) 16)) do
(return-from sortedp nil))
t)

(defun inversions (lst)
(if (or (null lst) (null (cdr lst)))
0
(let* ((half (ceiling (/ (length lst) 2)))
(left-list (subseq lst 0 half))
(right-list (subseq lst half)))
(+ (loop for a in left-list
summing (loop for b in right-list
counting (not (< a b))))
(inversions left-list)
(inversions right-list)))))

(defun solvablep (board)
(let ((inv (inversions (loop for i upto +max+ collecting
(row-major-aref board i))))
(row (- +side+ (first (board-position board 0)))))
(or (and (oddp +side+)
(evenp inv))
(and (evenp +side+)
(evenp row)
(oddp inv))
(and (evenp +side+)
(oddp row)
(evenp inv)))))

(defun board-position (board dig)
(loop for i below (car (array-dimensions board)) do
(loop for j below (cadr (array-dimensions board))
when (eq dig (aref board i j)) do
(return-from board-position (list i j)))))

(defun in-bounds (y x)
(and (< -1 y +side+)
(< -1 x +side+)))

(let ((adjacents ()) (y (first pos)) (x (second pos)))
(if (in-bounds y (1+ x))
(push (aref board y (1+ x)) adjacents))
(if (in-bounds (1+ y) x)
(push (aref board (1+ y) x) adjacents))
(if (in-bounds y (1- x))
(push (aref board y (1- x)) adjacents))
(if (in-bounds (1- y) x)
(push (aref board (1- y) x) adjacents))

(defun main (&rest argv)
(declare (ignorable argv))
(setf *random-state* (make-random-state t))
(loop until (solvablep *board*) do
(shuffle-board *board*))
(loop until (sortedp *board*) do
(format t "~/15:pb/~%" *board*)
(format t "Which number do you want to swap the blank with?~%> ")
(zpos (board-position *board* 0))
(pos (board-position *board* in))
(rotatef (aref *board* (first pos) (second pos))
(aref *board* (first zpos) (second zpos))))))
(format t "You win!~%"))
```

## Craft Basic

```rem 15 Puzzle example game
rem written in Craft Basic
rem by Gemino Smothers 2023
rem www.lucidapogee.com

define size = 16, correct = 0, moves = 0
define click = 0, start = 0

dim list[size]

gosub setup
gosub game

end

sub setup

title "15 Puzzle"

resize 0, 0, 170, 270
center

bgcolor 0,128,0
cls

let x = 0
let y = 30

for i = 0 to size - 1

if x = 112 then

let x = 0
let y = y + 25

endif

let x = x + 28

formid i + 1
formtext ""
buttonform x, y, 25, 20

next i

formid 17
formtext "
staticform 40, 130, 100, 20
bgcolor 0, 128, 0
fgcolor 255, 255, 0
colorform

formid 18
formtext ""
staticform 40, 150, 100, 20
bgcolor 0, 128, 0
fgcolor 255, 255, 0
colorform

formid 19
formtext "New"
buttonform 1, 1, 50, 20

formid 20
formtext "Help"
buttonform 55, 1, 50, 20

formid 21
buttonform 110, 1, 50, 20

formid 22
formtext "Welcome."
staticform 40, 170, 120, 20
bgcolor 0, 128, 0
fgcolor 255, 255, 0
colorform

return

sub shuffle

let start = 1

formid 22
formtext "shuffling..."
updateform

for i = 0 to size - 1

formid i + 1
formtext ""
updateform

let list[i] = 0

next i

let t = 0
let i = 0

do

if i = 14 then

let n = 120 - t

formid i + 1
formtext n
updateform

let list[i] = n

break

endif

for f = 0 to size - 1

let n = int(rnd * 15) + 1
let s = 0

for c = 0 to i - 1

if n = list[c] then

let s = 1
break c

endif

next c

if s = 0 and list[i] = 0 then

formid i + 1
formtext n
updateform

let list[i] = n
let t = t + n
let i = i + 1

endif

wait

next f

loop i < size - 1

formid 22
formtext ""
updateform

return

sub game

do

let click = forms

if click > 0 and click < 17 and start = 1 then

let moves = moves + 1

formid 17
formtext "Moves: ", moves
updateform

gosub checkspaces
gosub checkorder

endif

if click = 19 then

gosub shuffle

let moves = 0
let correct = 0

formid 17
formtext "Moves:"
updateform

formid 18
formtext "Correct:"
updateform

endif

if click = 20 then

alert "Click the numbers to move them in the correct order."

endif

if click =  21 then

alert "15 Puzzle", newline, "by Gemino Smothers 2023 ", newline, " www.basicgames.xyz"

endif

button k, 27

wait

loop k = 0

return

sub checkspaces

let click = click - 1
let top = click - 4
let right = click + 1
let bottom = click + 4
let left = click - 1

if top >= 0 then

if list[top] = 0 then

let n = top
gosub swap

endif

endif

if right <= size - 1 then

if list[right] = 0 then

let n = right
gosub swap

endif

endif

if bottom <= size - 1 then

if list[bottom] = 0 then

let n = bottom
gosub swap

endif

endif

if left >= 0 then

if list[left] = 0 then

let n = left
gosub swap

endif

endif

return

sub swap

let t = list[click]
let list[n] = list[click]
let list[click] = 0

let click = click + 1
formid click
formtext ""
updateform

let n = n + 1
formid n
formtext t
updateform

return

sub checkorder

let correct = 0

for i = 0 to size - 2

if list[i] = i + 1 then

let correct = correct + 1

endif

next i

formid 18
formtext "Correct: ", correct
updateform

if correct = size - 1 then

wait
alert "You win! Moves: ", moves

endif

return
```

## EasyLang

```sys topleft
background 432
textsize 13
len f[] 16
func draw . .
clear
for i = 1 to 16
h = f[i]
if h < 16
x = (i - 1) mod 4 * 24 + 3
y = (i - 1) div 4 * 24 + 3
color 210
move x y
rect 22 22
move x + 4 y + 6
if h < 10
move x + 6 y + 6
.
color 885
text h
.
.
.
global done .
func init . .
done = 0
for i = 1 to 16
f[i] = i
.
# shuffle
for i = 15 downto 2
r = random i
swap f[r] f[i]
.
# make it solvable
inv = 0
for i = 1 to 15
for j = 1 to i - 1
if f[j] > f[i]
inv += 1
.
.
.
if inv mod 2 <> 0
swap f[1] f[2]
.
textsize 12
call draw
.
func move_tile . .
c = mouse_x div 25
r = mouse_y div 25
i = r * 4 + c + 1
if c > 0 and f[i - 1] = 16
swap f[i] f[i - 1]
elif r > 0 and f[i - 4] = 16
swap f[i] f[i - 4]
elif r < 3 and f[i + 4] = 16
swap f[i] f[i + 4]
elif c < 3 and f[i + 1] = 16
swap f[i] f[i + 1]
.
call draw
done = 1
for i = 1 to 15
if f[i] > f[i + 1]
done = 0
.
.
if done = 1
clear
move 10 30
text "Well done!"
.
.
on mouse_down
if done = 1
call init
else
call move_tile
.
.
call init
```

## F#

```// 15 Puzzle Game. Nigel Galloway: August 9th., 2020
let Nr,Nc,RA,rnd=[|3;0;0;0;0;1;1;1;1;2;2;2;2;3;3;3|],[|3;0;1;2;3;0;1;2;3;0;1;2;3;0;1;2|],[|for n in [1..16]->n%16|],System.Random()
let rec fN g Σ=function h::t->fN g (Σ+List.sumBy(fun n->if h>n then 1 else 0)t) t|_->(Σ-g/4)%2=1
n when Seq.contains n g->printf "%c" n; (match n with 'l'-> -1|'r'->1|'d'->4|_-> -4)|_->System.Console.Beep(); fI g
let rec fG n Σ=function 0->(List.findIndex((=)0)Σ,Σ)|g->let i=List.item(rnd.Next(g)) n in fG(List.except [i] n)(i::Σ)(g-1)
let rec fE()=let n,g=fG [0..15] [] 16 in if fN n 0 (List.except [0] g) then (n,Array.ofList g) else fE()
let rec fL(n,g) Σ=let fa=printfn "";Array.chunkBySize 4 g|>Array.iter(fun n->Array.iter(printf "%3d")n;printfn "")
match g=RA with true->printfn "Solved in %d moves" Σ; fa; 0
|_->let vM=match n/4,n%4 with (0,0)->"rd"|(0,3)->"ld"|(0,_)->"lrd"|(3,0)->"ru"|(3,3)->"lu"|(3,_)->"lru"|(_,0)->"rud"|(_,3)->"lud"|_->"lrud"
fa; printf "Move Number: %2d; Manhatten Distance: %2d; Choose move from %4s: " Σ
([0..15]|>List.sumBy(fun n->match g.[n] with 0->0 |i->(abs(n/4-Nr.[i]))+(abs(n%4-Nc.[i])))) vM
let v=fI vM in g.[n]<-g.[n+v];g.[n+v]<-0;fL(n+v,g)(Σ+1)
[<EntryPoint>]
let main n = fL(match n with [|n|]->let g=[|let g=uint64 n in for n in 60..-4..0->int((g>>>n)&&&15UL)|] in (Array.findIndex((=)0)g,g) |_->fE()) 0
```

3 uses:

```15 game with no parameters will generate a random game which may be solved.
A solution in the form suggested in 15_puzzle_solver may be piped into 15game. "dddrurdruuulllddrulddrrruuullddruulldddrrurulldrruulldlddrurullddrrruullulddrdrr" | .\15game 0x0c9dfbae37254861 produces the output here: 15_puzzle_solver/extra_credit/solution.
Optionally a start position may be supplied. 15game 0x123450689a7bdefc may be solved:
```
Output:
```  1  2  3  4
5  0  6  8
9 10  7 11
13 14 15 12
Move Number:  0; Manhatten Distance:  4; Choose move from lrud: r
1  2  3  4
5  6  0  8
9 10  7 11
13 14 15 12
Move Number:  1; Manhatten Distance:  3; Choose move from lrud: d
1  2  3  4
5  6  7  8
9 10  0 11
13 14 15 12
Move Number:  2; Manhatten Distance:  2; Choose move from lrud: r
1  2  3  4
5  6  7  8
9 10 11  0
13 14 15 12
Move Number:  3; Manhatten Distance:  1; Choose move from  lud: d
1  2  3  4
5  6  7  8
9 10 11 12
13 14 15  0
Solved in 4 moves
```

## Factor

```USING: accessors combinators combinators.extras
combinators.short-circuit grouping io kernel literals math
math.matrices math.order math.parser math.vectors prettyprint qw
random sequences sequences.extras ;
IN: rosetta-code.15-puzzle-game

<<

TUPLE: board matrix zero ;

: <board> ( -- board )
16 <iota> 1 rotate 4 group { 3 3 } board boa ;

>>

CONSTANT: winning \$[ <board> matrix>> ]

: input>dir ( str -- pair )
{
{ "u" [ { 1 0 } ] }
{ "d" [ { -1 0 } ] }
{ "l" [ { 0 1 } ] }
{ "r" [ { 0 -1 } ] }
} case ;

: get-index ( loc matrix -- elt ) [ first2 swap ] dip nth nth ;

: mexchange ( loc1 loc2 matrix -- )
tuck [ [ [ get-index ] keepd ] 2bi@ ] keep [ spin ] 2dip
[ set-index ] keep set-index ;

: vclamp+ ( seq1 seq2 -- seq ) v+ { 0 0 } { 3 3 } vclamp ;

: slide-piece ( board str -- )
over zero>> [ vclamp+ ] keep rot matrix>> mexchange ;

: move-zero ( board str -- )
[ vclamp+ ] curry change-zero drop ;

: move ( board str -- )
input>dir [ slide-piece ] [ move-zero ] 2bi ;

: rand-move ( board -- ) qw{ u d l r } random move ;

: shuffle-board ( board n -- board' ) [ dup rand-move ] times ;

: .board ( board -- ) matrix>> simple-table. ;

: get-input ( -- str )
qw{ u d l r q } member? [ drop get-input ] unless ;

: won? ( board -- ? ) matrix>> winning = ;

DEFER: game
: process-input ( board -- board' )
get-input dup "q" = [ drop ] [ game ] if ;

: check-win ( board -- board' )
dup won? [ "You won!" print ] [ process-input ] if ;

: game ( board str -- board' )
[ move ] keepd dup .board check-win ;

: valid-difficulty? ( obj -- ? )
{ [ fixnum? ] [ 3 100 between? ] } 1&& ;

: choose-difficulty ( -- n )
"How many shuffles? (3-100) " write flush readln
string>number dup valid-difficulty?
[ drop choose-difficulty ] unless ;

: main ( -- )
<board> choose-difficulty shuffle-board dup .board check-win
drop ;

MAIN: main
```
Output:
```How many shuffles? (3-100) 5
1  2  3  4
5  6  7  8
9  0  10 12
13 14 11 15
1  2  3  4
5  6  7  8
9  10 0  12
13 14 11 15
1  2  3  4
5  6  7  8
9  10 11 12
13 14 0  15
1  2  3  4
5  6  7  8
9  10 11 12
13 14 15 0
You won!
```

## Forth

Works with: gforth version 0.7.2

The code tested with gforth 0.7.2. It required a 64-bit system.

See 15_puzzle_solver#Forth for a solver based on the same code.

```#! /usr/bin/gforth

cell 8 <> [if] s" 64-bit system required" exception throw [then]

\ In the stack comments below,
\ "h" stands for the hole position (0..15),
\ "s" for a 64-bit integer representing a board state,
\ "t" a tile value (0..15, 0 is the hole),
\ "b" for a bit offset of a position within a state,
\ "m" for a masked value (4 bits selected out of a 64-bit state),
\ "w" for a weight of a current path,
\ "d" for a direction constant (0..3)

\ Utility
: 3dup   2 pick 2 pick 2 pick ;
: 4dup   2over 2over ;
: shift   dup 0 > if lshift else negate rshift then ;

hex 123456789abcdef0 decimal constant solution
: row   2 rshift ;   : col   3 and ;

: up-valid?    ( h -- f ) row 0 > ;
: down-valid?  ( h -- f ) row 3 < ;
: left-valid?  ( h -- f ) col 0 > ;
: right-valid? ( h -- f ) col 3 < ;

\ To iterate over all possible directions, put direction-related functions into arrays:
: ith ( u addr -- w ) swap cells + @ ;
create valid? ' up-valid? , ' left-valid? , ' right-valid? , ' down-valid? , does> ith execute ;
create step -4 , -1 , 1 , 4 , does> ith ;

\ Advance from a single state to another:
: bits ( h -- b ) 15 swap - 4 * ;
: tile ( s b -- t ) rshift 15 and ;
: new-state ( s h d -- s' ) step dup >r + bits 2dup tile ( s b t ) swap lshift tuck - swap r> 4 * shift + ;

: hole? ( s u -- f ) bits tile 0= ;
: hole ( s -- h ) 16 0 do dup i hole? if drop i unloop exit then loop drop ;

0 constant up 1 constant left 2 constant right 3 constant down

\ Print a board:
: .hole   space space space ;
: .tile ( u -- ) ?dup-0=-if .hole else dup 10 < if space then . then ;
: .board ( s -- ) 4 0 do cr 4 0 do dup j 4 * i + bits tile .tile loop loop drop ;
: .help   cr ." ijkl move, q quit" ;

\ Pseudorandom number generator:
create (rnd)   utime drop ,
: rnd   (rnd) @ dup 13 lshift xor dup 17 rshift xor dup dup 5 lshift xor (rnd) ! ;

: move ( s u -- s' ) >r dup hole r> new-state ;
: ?move ( s u -- s' ) >r dup hole r@ valid? if r> move else rdrop then ;
: shuffle ( s u -- s' ) 0 do rnd 3 and ?move loop ;

: win   cr ." you won!" bye ;
: turn ( s -- )
page dup .board .help
key case
[char] q of bye endof
[char] i of down ?move endof
[char] j of right ?move endof
[char] k of up ?move endof
[char] l of left ?move endof
endcase ;

: play  begin dup solution <> while turn repeat win ;

solution 1000 shuffle play
```

## Fortran

The initial version had me so enamoured by the notion of consecutive cells for the solution having the number of their index as their value (as in CELL(0) = 0 (the blank square), CELL(1) = 1, ... CELL(15) = 15) and the prospect of the check for this being simple, that I failed to perceive that the nice big diagram of the board shown at the head of the article in fact clearly shows the solution state having the blank cell at the end, not the start. Once again it is demonstrated that what you see is ... influenced ... by what you would like to see. After that diversion, the cells shall now be numbered one to sixteen, not zero to fifteen, and so there is no need for the ability introduced by F90 whereby arrays can have a lower bound other than one.

The plan is to use parameters for the board size, which need not be square. As often with Fortran, messing with arrays is the key, though not without opportunities for confusion. Because Fortran stores arrays in column-major order, the arrays are accessed as BOARD(column,row) even though the arrangement is treated as rows down the page and columns across as is usual. By this means, consecutive elements in storage of array BOARD(c,r) are such that the same storage accessed via array BORED(i) thanks to `EQUIVALENCE(BOARD,BORED)` indexes them as consecutive elements, and so the test that the values are in consecutive order becomes delightfully simple, though alas there is no equivalent of the iota function of APL whereby the test could be `ALL(BORED(1:N - 1) .EQ. IOTA(N - 1))`

Column-major ordering also applies to array WAY, which lists the offsets needed to locate squares deemed adjacent to a given location, such as that of the blank square, located by LOCI = LOCZ + WAY(i). Adjacent LOCI are checked for being in range, and if so, added to the list in array LOCM with the moveable piece identified in array MOVE.

It transpires that the F90 compiler will not allow a PARAMETER statement to define values for items appearing in an EQUIVALENCE statement; so much for an attempt to do so in a systematic manner employing related names.

The game plan is to start with an ordered array so that each cell definitely has a unique code, then jumble them via "random" swaps. Possible arrangements turn out to have either odd or even parity based on the number of out-of-sequence squares, and as the allowed transformations do not change the parity and the solution state has even parity, odd parity starting states should not be presented except by those following Franz Kafka. The calculation is simplified by always having the blank square in the last position, thus in the last row. Once an even-parity starting state is floundered upon, the blank square is re-positioned using allowable moves so that the parity is not altered thereby. Then the game begins: single-square moves only are considered, though in practice groups of squares could be moved horizontally or vertically rather than one-step-at-a-time - a possible extension.

The source style uses F90 for its array arithmetic abilities, especially the functions ALL, ANY and COUNT. A statement
```LOCZ = MINLOC(BOARD)	!Find the zero. 0 = BOARD(LOCZ(1),LOCZ(2)) == BOARD(ZC,ZR)
```
could be used but is unnecessary thanks to tricks with EQUIVALENCE. For earlier Fortran, various explicit DO-loops would have to be used. This would at least make clear whether or not the equivalents of ANY and ALL terminated on the first failure or doggedly scanned the entire array no matter what.
```      SUBROUTINE SWAP(I,J)	!Alas, furrytran does not provide this.
INTEGER I,J,T		!So, we're stuck with supplying the obvious.
T = I			!And, only for one type at a go.
I = J			!One could define a MODULE containing a collection
J = T			!And thence a "generic" routine,
END SUBROUTINE SWAP	!But this will do for now.

SUBROUTINE SHOW(NR,NC,BOARD)	!The layout won't work for NC > 99...
INTEGER NR,NC		!Number of rows and columns.
INTEGER BOARD(NC,NR)	!The board is stored transposed!
INTEGER I		!A stepper.
COMMON/IODEV/ MSG	!I talk to the trees...
WRITE (MSG,1) (I,I = 1,NC)	!Prepare a heading.
1   FORMAT ("Row|",9("__",I1,:),90("_",I2,:))	!This should suffice.
DO I = 1,NR		!Chug down the rows.
WRITE (MSG,2) I,BOARD(1:NC,I)	!The columns of the row. Usage is BOARD(column,row).
2     FORMAT (I3,"|",99I3)	!Could use parameters, but enough.
END DO			!On to the next row.
END SUBROUTINE SHOW	!That was nice.

PROGRAM PUZZLE
INTEGER LOCN(2),NR,NC,N	!Describes the shape of the board.
INTEGER LOCZ(2),ZC,ZR	!Fingers the location of the "blank" square.
INTEGER LOCI(2),IC,IR	!Fingers a location.
Can't EQUIVALENCE (LOCN(1),NC),(LOCN(2),NR)	!This usage and a PARAMETER statement is too scary.
EQUIVALENCE (LOCZ(1),ZC),(LOCZ(2),ZR)	!Annotate my (column,row) usage.
EQUIVALENCE (LOCI(1),IC),(LOCI(2),IR)	!Rather than the displayed (row,column) style.
PARAMETER (NR = 4, NC = 4, N = NR*NC)	!Determine the shape of the board.
INTEGER BOARD(NC,NR)		!Thus transpose furrytran's column-major usage. Beware!!!
INTEGER BORED(N)			!This allows for consecutive comparisons.
EQUIVALENCE (BOARD,BORED)		!Because the arrays are in the same place.
PARAMETER (WAYS = 4)		!Just orthogonal neghbours.
INTEGER WAY(2,WAYS)		!Now list the allowed adjacencies.
PARAMETER (WAY = (/1,0, 0,1, -1,0, 0,-1/))	!W(1,1), W(2,1), W(1,2), W(2,2), W(1,3), ...
INTEGER M,MOVE(WAYS),LOCM(2,WAYS)	!Move possibilities.
INTEGER SPACE			!Document the empty square's code number.
PARAMETER (SPACE = 0)		!Zero will do.
INTEGER I,IT,PARITY,TRY		!Odds and ends.
REAL VALUE			!Humph. Yet another interface to a "random" number generator.
COMMON/IODEV/ MSG,KBD	!Pass the word.

KBD = 5	!Standard input. (Keyboard -> Display screen)
MSG = 6	!Standard output. (Display screen)
WRITE (MSG,1) NR,NC	!Announce.
1 FORMAT ("To play 'slide-square' with ",I0," rows and ",
1 I0," columns.",/,"The game is to slide a square into the space",/
2 "(thus leaving a space behind) until you attain"/
3 "the nice orderly layout as follows:",/)
Concoct a board layout.
10 FOR ALL (I = 1:N - 1) BORED(I) = I	!Prepare the board. Definitely unique values.
BORED(N) = SPACE	        !The empty square is not at the start! Oh well.
CALL SHOW(NR,NC,BOARD)	!Reveal the nice layout.
11 DO I = 1,N - 1		!Now shuffle the squares a bit.
CALL RANDOM(VALUE)		!0 <= VALUE < 1.
IT = VALUE*(N - 1) + 1		!1 <= IT < N. Don't round up!
IF (I.NE.IT) CALL SWAP(BORED(I),BORED(IT))	!Whee!
END DO			!On to the next victim, leaving the last cell alone.
Calculate the parity, knowing the space is at the end. The target state has even parity, with zero inversions.
PARITY = 0	!There are two classes of arrangements, that can't mix.
DO I = 1,N - 2	!Skipping the blank cell still at BORED(N).
PARITY = PARITY + COUNT(BORED(I) > BORED(I + 1:N - 1))	!For each square,
END DO		!Count the inversions following.
IF (MOD(PARITY,2).NE.0) GO TO 11	!No transition can change the parity, so, try for another arrangement.
Choose a new position for the space. Using approved moves will not change the parity.
CALL RANDOM(VALUE)		!0 <= VALUE < 1.
ZC = VALUE*(NC - 2) + 1		!1 <= ZC < NC: Choose a random column other than the last.
BOARD(ZC + 1:NC,NR) = BOARD(ZC:NC - 1,NR)	!Shift the end of the last row back one place.
BOARD(ZC,NR) = SPACE			!Put the space in the hole.
CALL RANDOM(VALUE)			!So the parity doesn't change.
ZR = VALUE*(NR - 2) + 1		!1 <= ZR < NR: Choose a random row, other than the last.
BOARD(ZC,ZR + 1:NR) = BOARD(ZC,ZR:NR - 1)	!Shift the end of column ZC up one.
BOARD(ZC,ZR) = SPACE			!Revive the space again.
Cast forth the starting position.
WRITE (MSG,12)		!Announce the result.
12 FORMAT (/,"But, your board looks like this...")	!Alas. Almost certainly not in order.
CALL SHOW(NR,NC,BOARD)	!Just so.
TRY = 0		!No moves made yet.

Consider possible moves.
20 TRY = TRY + 1	!Here we go again.
M = 0		!No moveable pieces are known.
DO I = 1,WAYS	!So scan the possible ways away from LOCZ.
LOCI = LOCZ + WAY(1:2,I)	!Finger an adjacent location, via the adjacency offsets in array WAY.
IF (ALL(LOCI > 0) .AND. ALL(LOCI <= (/NC,NR/))) THEN	!Within bounds?
M = M + 1			!Yes. We have a candidate.
MOVE(M) = BOARD(IC,IR)	!Record the piece's name.
LOCM(:,M) = LOCI		!And, remember where it is...
END IF			!So much for that location.
END DO		!Try another offset.
21 WRITE (MSG,22,ADVANCE="no") MOVE(1:M)	!Two-stage output.
22 FORMAT ("Moveable pieces: ",<WAYS>(I0:","))	!Since M is not necessarily WAYS, a trailing \$ may not be reached..
WRITE (MSG,23)		!Now for the question. Always at least two moveable squares.
23 FORMAT(". Choose one: ",\$)	!Continue the line, presuming screen and keyboard->screen.
READ (KBD,*) IT		!Now request the answer. Rather doggedly: blank lines won't do.
DO I = M,1,-1		!There are at least two possible moves.
IF (MOVE(I) .EQ. IT) EXIT	!Perhaps this piece was selected.
END DO			!The INDEX function is alas, only for CHARACTER variables. Grr.
IF (I .LE. 0) THEN	!I'm suspicious.
WRITE (MSG,*) "Huh? That is not a moveable piece!"	!Justified!
IF (IT.GT.0) GO TO 21		!Try again.
STOP "Oh well."			!Or quit, on negative vibrations.
END IF			!So much for selecting a piece.
Complete the selected move.
30 BOARD(ZC,ZR) = IT		!Place the named piece where the space was.
LOCZ = LOCM(:,I)		!The space is now where that piece came from.
BOARD(ZC,ZR) = SPACE		!And now holds a space.
c      write (6,*)
c     1 "disorder=",COUNT(BORED(1:N - 2) + 1 .NE. BORED(2:N - 1))
IF (TRY.LE.6) WRITE (MSG,31)	!Set off with a nice heading.
31 FORMAT (/"The new layout...")	!Just for clarity.
CALL SHOW(NR,NC,BOARD)		!Perhaps it will be good.
Check for success.
IF (BORED(N).NE.SPACE) GO TO 20	!Is the space at the end?
IF (ANY(BORED(1:N - 2) + 1 .NE. BORED(2:N - 1))) GO TO 20	!Are we there yet?
WRITE (MSG,*) TRY,"Steps to success!"	!Yes!
END	!That was fun.
```

Output: Not so good. As ever, the character cell sizes are not square so a square game board comes out as a rectangle. Similarly, underlining is unavailable (no overprints!) so the layout is not pleasing. There are special "box-drawing" glyphs available, but they are not standardised and there is still no overprinting so that a flabby waste of space results. Further, there is no ability to re-write the display, even though one could easily regard the output to the screen as a random-access file: `WRITE (MSG,REC = 6) STUFF` would rewrite the sixth line of the display. Instead, output relentlessly rolls forwards, starting as follows:

```To play 'slide-square' with 4 rows and 4 columns.
The game is to slide a square into the space
(thus leaving a space behind) until you attain
the nice orderly layout as follows:

Row|__1__2__3__4
1|  1  2  3  4
2|  5  6  7  8
3|  9 10 11 12
4| 13 14 15  0

But, your board looks like this...
Row|__1__2__3__4
1| 15  0 14 11
2|  8 13  5  3
3|  4  1  7  9
4| 10  6  2 12
Moveable pieces: 14,13,15. Choose one: 15

The new layout...
Row|__1__2__3__4
1|  0 15 14 11
2|  8 13  5  3
3|  4  1  7  9
4| 10  6  2 12
Moveable pieces: 15,8. Choose one:
```

The display here turns out to be less rectangular than that of the "console" screen's usual setting, which changes with the typeface and sizing anyway. Endless variation. As for playing the game, it is much easier to get a "feel" for the possibilities when manipulating the actual physical object. The digital world is less real.

## FreeBASIC

```sub drawboard( B() as ubyte )
dim as string outstr = ""
for i as ubyte = 0 to 15
if B(i) = 0 then
outstr = outstr + " XX "
elseif B(i) < 10 then
outstr = outstr + "  "+str(B(i))+" "
else
outstr = outstr + " " +str(B(i))+" "
end if
if i mod 4 = 3 then
print outstr
print
outstr = ""
end if
next i
print
end sub

function move( B() as ubyte, byref gap as ubyte, direction as ubyte ) as ubyte
dim as integer targ = gap
select case direction
case 1  'UP
targ = gap - 4
case 2  'RIGHT
if gap mod 4 = 3 then return gap
targ = gap + 1
case 3  'DOWN
targ = gap + 4
case 4
if gap mod 4 = 0 then return gap
targ = gap - 1
case else
return gap
end select
if targ > 15 or targ < 0 then return gap
swap B(targ), B(gap)
return targ
end function

sub shuffle( B() as ubyte, byref gap as ubyte )
for i as ubyte = 0 to 100
gap = move(B(), gap, int(rnd*4) + 1)
next i
end sub

function solved( B() as ubyte ) as boolean
dim as integer i
for i = 0 to 14
if B(i)>B(i+1) then return false
next i
return true
end function

dim as ubyte i, B(15), direction, gap
for i = 0 to 15
B(i) = i
next i
shuffle B(), gap

while not solved( B() )
cls
drawboard B()
print gap
print "1 = up, 2=right, 3=down, 4=left"
input direction
gap = move( B(), gap, direction )
wend

cls
print "Congratulations! You win!"
print
drawboard B()
```

## Gambas

```'Charlie Ogier (C) 15PuzzleGame 24/04/2017 V0.1.0 Licenced under MIT
'Inspiration came from: -
''http://rosettacode.org/wiki/15_Puzzle_Game
'Written in Gambas 3.9.2 - Updated on the Gambas Farm 01/05/2017
'Updated so that the message and the Title show the same amount of moves 01/06/2017
'Form now expandable. Font height automated. Form size and position saved 06/06/2107

'Simulate playing the 15 - game(puzzle)         Yes in GUI
'Generate a random start position               Yes
'Prompt the user for which piece To move        No
'Validate if the move is legal(possible)        Yes
'Display the game(puzzle) as pieces are moved   Yes in GUI
'Announce when the puzzle is solved             Yes
'Possibly keep track of the number of moves     Yes

byPos As New Byte[]                                             'Stores the position of the 'Tiles'
siMoves As Short                                                'Stores the amount of moves
hTimer As Timer                                                 'Timer
dTimerStart As Date                                             'Stores the start time
dTimerDiff As Date                                              'Stores the time from the start to now
bTimerOn As Boolean                                             'To know if the Timer is running

Public Sub Form_Open()                                          'Form opens

Settings.read(Me, "Window")                                     'Get details of the last window position and size
With Me                                                         'With the Form..
.Arrangement = Arrange.Row                                    'Arrange the Form
.Title = "15PuzzleGame v0.3.0"                                'Set the Form Title
End With

BuildForm                                                       'Go to the BuildForm routine

End

Public Sub BuildForm()                                          'To add items to the Form
Dim hButton As Button                                           'We need some Buttons
Dim byRand, byTest As Byte                                      'Various variables
Dim bOK As Boolean                                              'Used to stop duplicate numbers being added
Dim bSolvable As Boolean

Repeat                                                          'Repeat until the puzzle is solvable
Do                                                            'Start of a Do loop to create 0 to 15 in random order
byRand = Rand(0, 15)                                        'Get a random number between 0 and 15
If byRand = 0 Then byRand = 99                              'Change 0 to 99 for the Blank space
bOK = True                                                  'Set bOK to True
For Each byTest In byPos                                    'For each number stored in the array byPos
If byRand = byTest Then bOK = False                       'Check to see if it already exists, if it does set bOK to False
Next
If bOK Then byPos.Add(byRand)                               'If not a duplicate then add it to the array
If byPos.max = 15 Then Break                                'Once the array has 16 numbers get out of here. 99 is used for the blank space
Loop
bSolvable = IsItSolvable()                                    'Go to the 'check if puzzle is solvable' routine
If Not bSolvable Then byPos.clear                             'If it's not solvable then clear byPos
Until bSolvable = True                                          'Repeat until the puzzle is solvable

For byRand = 0 To 15                                            'Loop
If byPos[byRand] = 99 Then                                    'Check if value is 99 as this is where the blank space will go
Endif
hButton = New Button(Me) As "AllButtons"                      'Add a new button to the Form, all buttons grouped as 'AllButtons'
With hButton                                                  'With the following properties
.Text = Str(byPos[byRand])                                  'Add Button text
.Tag = Str(byPos[byRand])                                   'Add a Tag
.Height = (Me.Height - 10) / 4                              'Set the Button height
.Width = (Me.Width - 10) / 4                                'Set the Button width
.Font.Bold = True                                           'Set the font to Bold
.Font.Size = 16                                             'Set Font size
End With
Next

End

Public Sub AddPanel()                                           'Routine to add an invisible panel that is the blank area
Dim hPanel As Panel                                             'We need a Panel

HPanel = New Panel(Me)                                          'Add the Panel to the Form
With HPanel                                                     'With the following Properties
.Tag = 99                                                     'Set a Tag to 99
.Height = (Me.Height - 10) / 4                                'Set the height
.Width = (Me.Width - 10) / 4                                  'Set the width
End With

End

hTimer = New Timer As "MyTimer"                                 'Add a Timer
hTimer.Delay = 1000                                             'Set the timer delay

End

Public Sub MyTimer_Timer()                                      'Timer

Me.Title = siMoves & " Moves "                                  'Set the Form Title to show the amount of moves taken

If dTimerStart Then                                             'If a start time has been set then
dTimerDiff = Time(Now) - dTimerStart                          'Calculate the time difference between StartTime and Now
Me.Title &= " - " & Str(dTimerDiff)                           'Add the time taken to the Form Title
End If

End

Public Sub AllButtons_Click()                                   'What to do when a Button is clicked
Dim byLast As Byte = Last.Tag                                   'Get the Tag of the Button clicked
Dim byTemp, byCount As Byte                                     'Various variables
Dim byCheck As Byte[] = [88, 88, 88, 88]                        'Used for checking for the blank space
Dim byWChgeck As New Byte[16, 4]
Dim oObj As Object                                              'We need to enumerate Objects

For Each oObj In Me.Children                                    'For each Object (Buttons in this case) that are Children of the Form..
If oObj.Tag = byLast Then Break                               'If the Tag of the Button matches then we know the position of the Button on the form so get out of here
Inc byCount                                                   'Increase the value of byCount
Next

Select Case byCount                                             'Depending on the position of the Button
Case 0                                                        'e.g 0 then we need to check positions 1 & 4 for the blank
byCheck[0] = 1
byCheck[1] = 4
Case 1
byCheck[0] = 0
byCheck[1] = 2
byCheck[2] = 5
Case 2
byCheck[0] = 1
byCheck[1] = 3
byCheck[2] = 6
Case 3
byCheck[0] = 2
byCheck[1] = 7
Case 4
byCheck[0] = 0
byCheck[1] = 5
byCheck[2] = 8
Case 5                                                        'e.g 5 then we need to check positions 1, 4, 6 & 9 for the blank
byCheck[0] = 1
byCheck[1] = 4
byCheck[2] = 6
byCheck[3] = 9
Case 6
byCheck[0] = 2
byCheck[1] = 5
byCheck[2] = 7
byCheck[3] = 10
Case 7
byCheck[0] = 3
byCheck[1] = 6
byCheck[2] = 11
Case 8
byCheck[0] = 4
byCheck[1] = 9
byCheck[2] = 12
Case 9
byCheck[0] = 5
byCheck[1] = 8
byCheck[2] = 10
byCheck[3] = 13
Case 10
byCheck[0] = 6
byCheck[1] = 9
byCheck[2] = 11
byCheck[3] = 14
Case 11
byCheck[0] = 7
byCheck[1] = 10
byCheck[2] = 15
Case 12
byCheck[0] = 8
byCheck[1] = 13
Case 13
byCheck[0] = 9
byCheck[1] = 12
byCheck[2] = 14
Case 14
byCheck[0] = 10
byCheck[1] = 13
byCheck[2] = 15
Case 15
byCheck[0] = 11
byCheck[1] = 14
End Select

For Each byTemp In byCheck                                      'For each value in byCheck
If byTemp = 88 Then Break                                     'If byTemp = 88 then get out of here
If byPos[byTemp] = 99 Then                                    'If the position checked is 99 (the blank) then..
byPos[byTemp] = Last.Text                                   'Set the new position of the Tile in byPos
byPos[byCount] = 99                                         'Set the existing Tile position to = 99 (blank)
Inc siMoves                                                 'Inc the amount of moves made
If Not bTimerOn Then                                        'If the Timer is now needed then
dTimerStart = Time(Now)                                   'Set the Start time to NOW
hTimer.start                                              'Start the Timer
bTimerOn = True                                           'Set bTimerOn to True
Endif
Break                                                       'Get out of here
End If
Next

RebuildForm                                                     'Go to the RebuilForm routine
CheckIfPuzzleCompleted                                          'Check to see if the puzzle has been solved

End

Public Sub CheckIfPuzzleCompleted()                             'Is the puzzle is complete
Dim byTest As Byte[] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 99] 'byPos will equal this if it is completed
Dim siCount As Short                                            'Counter
Dim bCompleted As Boolean = True                                'Completed?
Dim sMessage As String                                          'String to store the display message

For siCount = 0 To 15                                           'Loop through the byPos
If byPos[siCount] <> byTest[siCount] Then                     'If the position does not match the completed position then..
bCompleted = False                                          'Set bCompleted to False
Break                                                       'Get out of here
Endif
Next

If bCompleted Then                                              'If the puzzle is completed then
hTimer.Stop                                                   'Stop the timer
Me.Title = siMoves & " Moves "                                'Set the Form Title to show the amount of moves taken
sMessage = "Congratulations!!\n"                              'Build sMessage
sMessage &= Str(siMoves) & " Moves\n"                         'Build sMessage
sMessage &= "Time = " & Str(dTimerDiff)                       'Build sMessage
Message(sMessage, "OK")                                       'Put up a congratulatory message
Me.Close                                                      'Close the form
Endif

End

Public Sub RebuildForm()                                        'To clear the Form and rebuild with the Tiles in the new postion
Dim hButton As Button                                           'We need Buttons
Dim byCount, byTemp As Byte                                     'Various variables
Dim siFontH As Short

Me.Children.clear                                               'Clear the Form of all Objects

For Each byTemp In byPos                                        'For each 'Position'
If byTemp = 99 Then                                           'If the Position's value is 99 then it's the space
Else                                                          'If the Position's value is NOT 99 then
hButton = New Button(Me) As "AllButtons"                    'Create a new Button
With hButton                                                  'With the following properties
.Text = Str(byPos[byCount])                                 'Text as stored in byPos
.Tag = Str(byPos[byCount])                                  'Tag as stored in byPos
.Height = (Me.Height - 10) / 4                              'Set the Button height
.Width = (Me.Width - 10) / 4                                'Set the Button width
.Font.Bold = True                                           'Set the Font to Bold
End With
If Me.Width > Me.Height Then                                'If Form Width is greater than Form Width then..
siFontH = Me.Height                                       'siFontH = Form Height
Else                                                        'Else..
siFontH = Me.Width                                        'siFontH = Form Width
End If
hButton.Font.size = siFontH / 16                              'Set Font height
Endif

Inc byCount                                                   'Increase counter
Next

End

Public Sub Form_Resize()                                        'If the form is resized

RebuildForm                                                     'Rebuild the Form

End

Public Sub IsItSolvable() As Boolean                            'To check if the puzzle is solvable
Dim bSolvable, bBlankOnEven As Boolean                          'Triggers
Dim siCount0, siCount1, siInversion As Short                    'Counters

For siCount0 = 0 To byPos.Max                                   'Loop through the positions
If byPos[siCount0] = 99 Then                                  'The blank
If InStr("0,1,2,3,8,9,10,11,", Str(siCount0 & ",")) Then    'Is the blank on an even row (counting from the bottom) if so..
bBlankOnEven = True                                       'bBlankOnEven = True
End If
Continue                                                    'Go to the end of the loop
End If
For siCount1 = siCount0 + 1 To byPos.Max                      'Loop through the positions
If byPos[siCount0] > byPos[siCount1] Then Inc siInversion   'Counts the inversions
Next                                                          'See https://www.cs.bham.ac.uk/~mdr/teaching/modules04/java2/TilesSolvability.html
Next

If bBlankOnEven And Odd(siInversion) Then bSolvable = True      'Blank is on an even row (counting from the bottom) then the number of inversions in a solvable situation is odd
If Not bBlankOnEven And Even(siInversion) Then bSolvable = True 'Blank is on an odd row (counting from the bottom) then the number of inversions in a solvable situation is even

Return bSolvable                                                'Return the value

End

Public Sub Form_Close()

Settings.Write(Me, "Window")                                    'Store the window position and size

End
```

## Go

```package main

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

func main() {
rand.Seed(time.Now().UnixNano())
p := newPuzzle()
p.play()
}

type board [16]cell
type cell uint8
type move uint8

const (
up move = iota
down
right
left
)

func randMove() move { return move(rand.Intn(4)) }

var solvedBoard = board{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0}

func (b *board) String() string {
var buf strings.Builder
for i, c := range b {
if c == 0 {
buf.WriteString("  .")
} else {
_, _ = fmt.Fprintf(&buf, "%3d", c)
}
if i%4 == 3 {
buf.WriteString("\n")
}
}
return buf.String()
}

type puzzle struct {
board board
empty int // board[empty] == 0
moves int
quit  bool
}

func newPuzzle() *puzzle {
p := &puzzle{
board: solvedBoard,
empty: 15,
}
// Could make this configurable, 10==easy, 50==normal, 100==hard
p.shuffle(50)
return p
}

func (p *puzzle) shuffle(moves int) {
// As with other Rosetta solutions, we use some number
// of random moves to "shuffle" the board.
for i := 0; i < moves || p.board == solvedBoard; {
if p.doMove(randMove()) {
i++
}
}
}

func (p *puzzle) isValidMove(m move) (newIndex int, ok bool) {
switch m {
case up:
return p.empty - 4, p.empty/4 > 0
case down:
return p.empty + 4, p.empty/4 < 3
case right:
return p.empty + 1, p.empty%4 < 3
case left:
return p.empty - 1, p.empty%4 > 0
default:
panic("not reached")
}
}

func (p *puzzle) doMove(m move) bool {
i := p.empty
j, ok := p.isValidMove(m)
if ok {
p.board[i], p.board[j] = p.board[j], p.board[i]
p.empty = j
p.moves++
}
return ok
}

func (p *puzzle) play() {
fmt.Printf("Starting board:")
for p.board != solvedBoard && !p.quit {
fmt.Printf("\n%v\n", &p.board)
p.playOneMove()
}
if p.board == solvedBoard {
fmt.Printf("You solved the puzzle in %d moves.\n", p.moves)
}
}

func (p *puzzle) playOneMove() {
for {
fmt.Printf("Enter move #%d (U, D, L, R, or Q): ", p.moves+1)
var s string
if n, err := fmt.Scanln(&s); err != nil || n != 1 {
continue
}

s = strings.TrimSpace(s)
if s == "" {
continue
}

var m move
switch s[0] {
case 'U', 'u':
m = up
case 'D', 'd':
m = down
case 'L', 'l':
m = left
case 'R', 'r':
m = right
case 'Q', 'q':
fmt.Printf("Quiting after %d moves.\n", p.moves)
p.quit = true
return
default:
fmt.Println(`
Please enter "U", "D", "L", or "R" to move the empty cell
up, down, left, or right. You can also enter "Q" to quit.
Upper or lowercase is accepted and only the first non-blank
character is important (i.e. you may enter "up" if you like).
`)
continue
}

if !p.doMove(m) {
fmt.Println("That is not a valid move at the moment.")
continue
}

return
}
}
```

## Harbour

```#include "inkey.ch"
#include "Box.ch"

procedure Main()
// console init
SET SCOREBOARD OFF
SetMode(30,80)
ret := 0

// main loop
yn := .F.
DO WHILE yn == .F.
// draw console
cls
@ 0, 0 TO MaxRow(), MaxCol() DOUBLE
SetColor("BG+/B,W/N")
@ 0, 4 SAY "  Slidng puzzle game  "
SetColor()

// input size of grid
tam := 0
@ MaxRow() - 2, 4 SAY "Size of grid: " GET tam PICTURE "9"

// Initialize numbers
lista := ARRAY (tam * tam)
FOR z := 1 TO tam * tam
lista[z] := z
NEXT
lista1 := lista
grid := ARRAY (tam,tam)

// populate grid with numbers
FOR i := 1 TO tam
FOR j := 1 TO tam
grid[i,j] := lista1[ (i-1) * tam + j]
NEXT
NEXT
Mostra(@grid)
InKey(0)

// initialize the game
n := 0
t := 0
lista := lista1     // lista for scrambling, lista1 preserve numbers in order
DO WHILE .T.
// scrambling numbers
FOR i := 1 TO tam*tam
n := Int ( ft_Rand1(tam * tam - 1) + 1 )
t := lista[n]
lista[n] := lista[i]
lista[i] := t
NEXT
// have solution?
possp := 0
invct := 0  // change counter
FOR i := 1 TO tam * tam -1
IF lista[i] != tam*tam
FOR j := i + 1 TO tam * tam
IF lista[j] != tam*tam
IF lista[i] > lista[j]
invct++
ENDIF
ENDIF
NEXT
ELSE
possp := i
ENDIF
NEXT
linv := If( ( (invct % 2) == 0 ), .T., .F.)
lkin := If( ( (tam - Int( (possp -1) / tam )) % 2) == 0, .T., .F. )

IF ( (tam % 2) != 0)    // if grid size is odd
IF linv                 // if number of positions changes is even, solvable
EXIT
ELSE
LOOP                // if is odd, not solvable, scramble more
ENDIF               // if grid size is even
ELSE
// If changes is even and space position is in odd line
// or changes is odd and space position is in even line
// (XOR condition) is solvable
IF (linv .AND. !lkin) .OR. (!linv .AND. lkin) // XOR !!!
EXIT
ElSE                    // else scramble more
LOOP
ENDIF
ENDIF

ENDDO

// populate the grid with scrambled numbers
FOR i := 1 TO tam
FOR j := 1 TO tam
grid[i,j] := lista[ (i-1) * tam + j]
NEXT
NEXT
ret := Mostra(@grid)

// play
key := 0
DO WHILE LastKey() != K_ESC
key := 0
// find the space coords
xe := 0
ye := 0
lv := tam*tam
FOR i := 1 TO tam
FOR j := 1 TO tam
IF grid[i,j] == lv
xe :=i
ye :=j
ENDIF
NEXT
NEXT
// the direction keys
key := inkey(0)
DO CASE
CASE key == K_UP
IF xe > 1
grid[xe,ye] := grid[xe-1,ye]
grid[xe-1,ye] := lv
ENDIF
ret := Mostra(@grid)
CASE key == K_DOWN
IF xe < tam
grid[xe,ye] := grid[xe+1,ye]
grid[xe+1,ye] := lv
ENDIF
ret := Mostra(@grid)
CASE key == K_LEFT
IF ye > 1
grid[xe,ye] := grid[xe,ye-1]
grid[xe,ye-1] := lv
ENDIF
ret := Mostra(@grid)
CASE key == K_RIGHT
IF ye < tam
grid[xe,ye] := grid[xe,ye+1]
grid[xe,ye+1] := lv
ENDIF
ret := Mostra(@grid)
ENDCASE
IF ret == tam*tam-1                             // ret is qtty numbers in position
@ MaxRow() - 3, 4 SAY "Fim de jogo!"        // if ret == (size*size) -1
key := K_ESC                                // all numbers in position
EXIT                                        // game solved
ENDIF
ENDDO
@ MaxRow() - 2, 4 SAY "Deseja sair? (yn): " GET yn PICTURE "Y"
@ MaxRow() - 3, 4 SAY "              "
ENDDO
return NIL

FUNCTION Mostra(grid)
// Show the gris
fim := 0                                                    // how many numbers in position?
SetColor("BG+/B,W/N")
@ 5,10 , 5 + tam * 2, 9 + tam * 4 BOX B_SINGLE + Space(1)
i := 0
FOR y := 1 TO tam
FOR x := 1 TO tam
IF grid[x,y] == tam * tam                           // show space
SetColor(" B/GR+, W/N")
@ x*2 + 4, i + 11 SAY "  "
SetColor("BG+/B,W/N")
ELSE
IF ( (x-1) * tam + y ) == grid[x,y]             // show number in position
SetColor("W/G,W/N")
@ x*2 + 4, i + 11 SAY grid[x,y] PICTURE "99"
fim++
ELSE                                            // show number out position
SetColor("BG+/B,W/N")
@ x*2 + 4, i + 11 SAY grid[x,y] PICTURE "99"
ENDIF
ENDIF
NEXT
i = i + 4
NEXT
SetColor(" W/N, BG+/B")
RETURN fim```

```import Data.Array
import System.Random

type Puzzle = Array (Int, Int) Int

main :: IO ()
main = do
putStrLn "Please enter the difficulty level: 0, 1 or 2"
userInput <- getLine
if userInput == "" || any (\c -> c < '0' || c > '9') userInput || diffLevel > 2 || diffLevel < 0
then putStrLn "That is not a valid difficulty level." >> main
else shufflePuzzle ([10, 50, 100] !! diffLevel) solvedPuzzle >>= gameLoop

gameLoop :: Puzzle -> IO ()
gameLoop puzzle
| puzzle == solvedPuzzle = putStrLn "You solved the puzzle!" >> printPuzzle puzzle
| otherwise = do
printPuzzle puzzle
putStrLn "Please enter number to move"
userInput <- getLine
if any (\c -> c < '0' || c > '9') userInput
then putStrLn "That is not a valid number." >> gameLoop puzzle
else let move = read userInput in
if move `notElem` validMoves puzzle
then putStrLn "This move is not available." >> gameLoop puzzle
else gameLoop (applyMove move puzzle)

validMoves :: Puzzle -> [Int]
validMoves puzzle = [puzzle ! (row', column') |
row' <- [rowEmpty-1..rowEmpty+1], column' <- [columnEmpty-1..columnEmpty+1],
row' < 4, row' >= 0, column' < 4, column' >= 0,
(row' == rowEmpty) /= (column' == columnEmpty)]
where (rowEmpty, columnEmpty) = findIndexOfNumber 16 puzzle

applyMove :: Int -> Puzzle -> Puzzle
applyMove numberToMove puzzle = puzzle // [(indexToMove, 16), (emptyIndex, numberToMove)]
where indexToMove = findIndexOfNumber numberToMove puzzle
emptyIndex = findIndexOfNumber 16 puzzle

findIndexOfNumber :: Int -> Puzzle -> (Int, Int)
findIndexOfNumber number puzzle = case filter (\idx -> number == puzzle ! idx)
(indices puzzle) of
[idx] -> idx
_ -> error "BUG: number not in puzzle"

printPuzzle :: Puzzle -> IO ()
printPuzzle puzzle = do
putStrLn "+--+--+--+--+"
putStrLn \$ "|" ++ formatCell (0, 0) ++ "|" ++ formatCell (0, 1) ++ "|" ++ formatCell (0, 2) ++ "|" ++ formatCell (0, 3) ++ "|"
putStrLn "+--+--+--+--+"
putStrLn \$ "|" ++ formatCell (1, 0) ++ "|" ++ formatCell (1, 1) ++ "|" ++ formatCell (1, 2) ++ "|" ++ formatCell (1, 3) ++ "|"
putStrLn "+--+--+--+--+"
putStrLn \$ "|" ++ formatCell (2, 0) ++ "|" ++ formatCell (2, 1) ++ "|" ++ formatCell (2, 2) ++ "|" ++ formatCell (2, 3) ++ "|"
putStrLn "+--+--+--+--+"
putStrLn \$ "|" ++ formatCell (3, 0) ++ "|" ++ formatCell (3, 1) ++ "|" ++ formatCell (3, 2) ++ "|" ++ formatCell (3, 3) ++ "|"
putStrLn "+--+--+--+--+"
where formatCell idx
| i == 16 = "  "
| i > 9 = show i
| otherwise = " " ++ show i
where i = puzzle ! idx

solvedPuzzle :: Puzzle
solvedPuzzle = listArray ((0, 0), (3, 3)) [1..16]

shufflePuzzle :: Int -> Puzzle -> IO Puzzle
shufflePuzzle 0 puzzle = return puzzle
shufflePuzzle numOfShuffels puzzle = do
let moves = validMoves puzzle
randomIndex <- randomRIO (0, length moves - 1)
let move = moves !! randomIndex
shufflePuzzle (numOfShuffels - 1) (applyMove move puzzle)
```

Output:

```Please enter the difficulty level: 0, 1 or 2
0
+--+--+--+--+
| 1| 6| 2| 4|
+--+--+--+--+
| 5|10| 3| 8|
+--+--+--+--+
| 9|14| 7|11|
+--+--+--+--+
|13|  |15|12|
+--+--+--+--+
14
+--+--+--+--+
| 1| 6| 2| 4|
+--+--+--+--+
| 5|10| 3| 8|
+--+--+--+--+
| 9|  | 7|11|
+--+--+--+--+
|13|14|15|12|
+--+--+--+--+

## J

Implementation:

```require'general/misc/prompt'

genboard=:3 :0
b=. ?~16
if. 0<C.!.2 b do.
b=. (<0 _1)C. b
end.
a: (b i.0)} <"0 b
)

done=: (<"0]1+i.15),a:

shift=: |.!._"0 2
taxi=: |:,/"2(_1 1 shift i.4 4),_1 1 shift"0 1/ i.4 4

showboard=:3 :0
echo 'current board:'
echo 4 4\$y
)

help=:0 :0

Slide a number block into the empty space
until you get:
┌──┬──┬──┬──┐
│1 │2 │3 │4 │
├──┼──┼──┼──┤
│5 │6 │7 │8 │
├──┼──┼──┼──┤
│9 │10│11│12│
├──┼──┼──┼──┤
│13│14│15│  │
└──┴──┴──┴──┘
Or type 'q' to quit.
)

getmove=:3 :0
showboard y
blank=. y i. a:
options=. /:~ ;y {~ _ -.~ blank { taxi
whilst. -. n e. options do.
echo 'Valid moves: ',":options
t=. prompt 'move which number? '
if. 'q' e. t do.
echo 'giving up'
throw.
elseif. 'h' e. t do.
echo help
showboard y
end.
n=. {._".t
end.
(<blank,y i.<n) C. y
)

game=: 3 :0
echo '15 puzzle'
echo 'h for help, q to quit'
board=. genboard''
whilst. -. done-:board do.
board=. getmove board
end.
showboard board
echo 'You win.'
)
```

Most of this is user interface code. We initially shuffle the numbers randomly, then check their parity and swap the first and last squares if needed. Then, for each move, we allow the user to pick one of the taxicab neighbors of the empty square.

A full game would be too big to be worth showing here, so for the purpose of giving a glimpse of what this looks like in action we replace the random number generator with a constant:

```   game''
15 puzzle
h for help, q to quit
current board:
┌──┬──┬──┬──┐
│1 │2 │3 │4 │
├──┼──┼──┼──┤
│5 │6 │7 │8 │
├──┼──┼──┼──┤
│9 │10│  │11│
├──┼──┼──┼──┤
│13│14│15│12│
└──┴──┴──┴──┘
Valid moves: 7 10 11 15
move which number? 11
current board:
┌──┬──┬──┬──┐
│1 │2 │3 │4 │
├──┼──┼──┼──┤
│5 │6 │7 │8 │
├──┼──┼──┼──┤
│9 │10│11│  │
├──┼──┼──┼──┤
│13│14│15│12│
└──┴──┴──┴──┘
Valid moves: 8 11 12
move which number? 12
current board:
┌──┬──┬──┬──┐
│1 │2 │3 │4 │
├──┼──┼──┼──┤
│5 │6 │7 │8 │
├──┼──┼──┼──┤
│9 │10│11│12│
├──┼──┼──┼──┤
│13│14│15│  │
└──┴──┴──┴──┘
You win.
```

## Java

Works with: Java version 8
```package fifteenpuzzle;

import java.awt.*;
import java.awt.event.*;
import java.util.Random;
import javax.swing.*;

class FifteenPuzzle extends JPanel {

private final int side = 4;
private final int numTiles = side * side - 1;

private final Random rand = new Random();
private final int[] tiles = new int[numTiles + 1];
private final int tileSize;
private int blankPos;
private final int margin;
private final int gridSize;
private boolean gameOver;

private FifteenPuzzle() {
final int dim = 640;

margin = 80;
tileSize = (dim - 2 * margin) / side;
gridSize = tileSize * side;

setPreferredSize(new Dimension(dim, dim + margin));
setBackground(Color.WHITE);
setForeground(new Color(0x6495ED)); // cornflowerblue
setFont(new Font("SansSerif", Font.BOLD, 60));

gameOver = true;

@Override
public void mousePressed(MouseEvent e) {
if (gameOver) {
newGame();

} else {

int ex = e.getX() - margin;
int ey = e.getY() - margin;

if (ex < 0 || ex > gridSize || ey < 0 || ey > gridSize) {
return;
}

int c1 = ex / tileSize;
int r1 = ey / tileSize;
int c2 = blankPos % side;
int r2 = blankPos / side;

int clickPos = r1 * side + c1;

int dir = 0;
if (c1 == c2 && Math.abs(r1 - r2) > 0) {
dir = (r1 - r2) > 0 ? 4 : -4;

} else if (r1 == r2 && Math.abs(c1 - c2) > 0) {
dir = (c1 - c2) > 0 ? 1 : -1;
}

if (dir != 0) {
do {
int newBlankPos = blankPos + dir;
tiles[blankPos] = tiles[newBlankPos];
blankPos = newBlankPos;
} while (blankPos != clickPos);
tiles[blankPos] = 0;
}

gameOver = isSolved();
}
repaint();
}
});

newGame();
}

private void newGame() {
do {
reset();
shuffle();
} while (!isSolvable());
gameOver = false;
}

private void reset() {
for (int i = 0; i < tiles.length; i++) {
tiles[i] = (i + 1) % tiles.length;
}
blankPos = tiles.length - 1;
}

private void shuffle() {
// don't include the blank space in the shuffle, leave it
// in the home position
int n = numTiles;
while (n > 1) {
int r = rand.nextInt(n--);
int tmp = tiles[r];
tiles[r] = tiles[n];
tiles[n] = tmp;
}
}

/*  Only half the permutations of the puzzle are solvable.

Whenever a tile is preceded by a tile with higher value it counts
as an inversion. In our case, with the blank space in the home
position, the number of inversions must be even for the puzzle
to be solvable.

www.cs.bham.ac.uk/~mdr/teaching/modules04/java2/TilesSolvability.html
*/
private boolean isSolvable() {
int countInversions = 0;
for (int i = 0; i < numTiles; i++) {
for (int j = 0; j < i; j++) {
if (tiles[j] > tiles[i]) {
countInversions++;
}
}
}
return countInversions % 2 == 0;
}

private boolean isSolved() {
if (tiles[tiles.length - 1] != 0) {
return false;
}
for (int i = numTiles - 1; i >= 0; i--) {
if (tiles[i] != i + 1) {
return false;
}
}
return true;
}

private void drawGrid(Graphics2D g) {
for (int i = 0; i < tiles.length; i++) {
int r = i / side;
int c = i % side;
int x = margin + c * tileSize;
int y = margin + r * tileSize;

if (tiles[i] == 0) {
if (gameOver) {
g.setColor(Color.GREEN);
drawCenteredString(g, "\u2713", x, y);
}
continue;
}

g.setColor(getForeground());
g.fillRoundRect(x, y, tileSize, tileSize, 25, 25);
g.setColor(Color.blue.darker());
g.drawRoundRect(x, y, tileSize, tileSize, 25, 25);
g.setColor(Color.WHITE);

drawCenteredString(g, String.valueOf(tiles[i]), x, y);
}
}

private void drawStartMessage(Graphics2D g) {
if (gameOver) {
g.setFont(getFont().deriveFont(Font.BOLD, 18));
g.setColor(getForeground());
String s = "click to start a new game";
int x = (getWidth() - g.getFontMetrics().stringWidth(s)) / 2;
int y = getHeight() - margin;
g.drawString(s, x, y);
}
}

private void drawCenteredString(Graphics2D g, String s, int x, int y) {
FontMetrics fm = g.getFontMetrics();
int asc = fm.getAscent();
int des = fm.getDescent();

x = x + (tileSize - fm.stringWidth(s)) / 2;
y = y + (asc + (tileSize - (asc + des)) / 2);

g.drawString(s, x, y);
}

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

drawGrid(g);
drawStartMessage(g);
}

public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setTitle("Fifteen Puzzle");
f.setResizable(false);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
});
}
}
```

## JavaScript

Play it here

```var board, zx, zy, clicks, possibles, clickCounter, oldzx = -1, oldzy = -1;
function getPossibles() {
var ii, jj, cx = [-1, 0, 1, 0], cy = [0, -1, 0, 1];
possibles = [];
for( var i = 0; i < 4; i++ ) {
ii = zx + cx[i]; jj = zy + cy[i];
if( ii < 0 || ii > 3 || jj < 0 || jj > 3 ) continue;
possibles.push( { x: ii, y: jj } );
}
}
function updateBtns() {
var b, v, id;
for( var j = 0; j < 4; j++ ) {
for( var i = 0; i < 4; i++ ) {
id = "btn" + ( i + j * 4 );
b = document.getElementById( id );
v = board[i][j];
if( v < 16 ) {
b.innerHTML = ( "" + v );
b.className = "button"
}
else {
b.innerHTML = ( "" );
b.className = "empty";
}
}
}
clickCounter.innerHTML = "Clicks: " + clicks;
}
function shuffle() {
var v = 0, t;
do {
getPossibles();
while( true ) {
t = possibles[Math.floor( Math.random() * possibles.length )];
console.log( t.x, oldzx, t.y, oldzy )
if( t.x != oldzx || t.y != oldzy ) break;
}
oldzx = zx; oldzy = zy;
board[zx][zy] = board[t.x][t.y];
zx = t.x; zy = t.y;
board[zx][zy] = 16;
} while( ++v < 200 );
}
function restart() {
shuffle();
clicks = 0;
updateBtns();
}
function checkFinished() {
var a = 0;
for( var j = 0; j < 4; j++ ) {
for( var i = 0; i < 4; i++ ) {
if( board[i][j] < a ) return false;
a = board[i][j];
}
}
return true;
}
function btnHandle( e ) {
getPossibles();
var c = e.target.i, r = e.target.j, p = -1;
for( var i = 0; i < possibles.length; i++ ) {
if( possibles[i].x == c && possibles[i].y == r ) {
p = i;
break;
}
}
if( p > -1 ) {
clicks++;
var t = possibles[p];
board[zx][zy] = board[t.x][t.y];
zx = t.x; zy = t.y;
board[zx][zy] = 16;
updateBtns();
if( checkFinished() ) {
setTimeout(function(){
restart();
}, 1);
}
}
}
function createBoard() {
board = new Array( 4 );
for( var i = 0; i < 4; i++ ) {
board[i] = new Array( 4 );
}
for( var j = 0; j < 4; j++ ) {
for( var i = 0; i < 4; i++ ) {
board[i][j] = ( i + j * 4 ) + 1;
}
}
zx = zy = 3; board[zx][zy] = 16;
}
function createBtns() {
var b, d = document.createElement( "div" );
d.className += "board";
document.body.appendChild( d );
for( var j = 0; j < 4; j++ ) {
for( var i = 0; i < 4; i++ ) {
b = document.createElement( "button" );
b.id = "btn" + ( i + j * 4 );
b.i = i; b.j = j;
b.appendChild( document.createTextNode( "" ) );
d.appendChild( b );
}
}
clickCounter = document.createElement( "p" );
clickCounter.className += "txt";
document.body.appendChild( clickCounter );
}
function start() {
createBtns();
createBoard();
restart();
}
```

Html to test

```<!DOCTYPE html>
<title>15 Puzzle</title>
<script src="p15.js"></script>
<style>
.txt{color:#fff;text-align:center;font-size:5vh}
.empty{background:#333;border:1px solid #111}
</style>
```

## Julia

```using Random

const size = 4
const puzzle = string.(reshape(1:16, size, size))
puzzle[16] = " "
rng = MersenneTwister(Int64(round(time())))
shufflepuzzle() = (puzzle .= shuffle(rng, puzzle))
findtile(t) = findfirst(x->x == t, puzzle)
findhole() = findtile(" ")

function issolvable()
inversioncount = 1
asint(x) = (puzzle[x] == " ") ? 0 : parse(Int64, puzzle[x])
for i in 1:size^2-1, j in i:size^2
if puzzle[i] == " " || puzzle[j] == " "
continue
end
if parse(Int, puzzle[i]) < parse(Int, puzzle[j])
inversioncount += 1
end
end
if size % 2 == 1
return inversioncount % 2 == 0
end
pos = findhole()
inversioncount += pos[2]
return inversioncount & 1 == 0
end

function nexttohole()
holepos = findhole()
row = holepos[1]
col = holepos[2]
if row == 1
if col == 1
return [[row, col + 1], [row + 1, col]]
elseif col == size
return [[row, col - 1], [row + 1, col]]
else
return [[row, col - 1], [row, col + 1], [row + 1, col]]
end
elseif row == size
if col == 1
return [[row - 1, col], [row, col + 1]]
elseif col == size
return [[row - 1, col], [row, col - 1]]
else
return [[row - 1, col], [row, col - 1], [row, col + 1]]
end
else
if col == 1
return [[row - 1, col], [row, col + 1], [row + 1, col]]
elseif col == size
return [[row - 1, col], [row, col - 1], [row + 1, col]]
else
return [[row - 1, col], [row, col - 1], [row, col + 1], [row + 1, col]]
end
end
end

possiblemoves() = map(pos->puzzle[pos[1], pos[2]], nexttohole())

function movehole(tiletofill)
if tiletofill in possiblemoves()
curpos = findtile(tiletofill)
holepos = findhole()
puzzle[holepos] = tiletofill
puzzle[curpos] = " "
else
println("Bad tile move \$tiletofill.\nPossible moves are \$(possiblemoves()).")
end
end

function printboard()
print("+----+----+----+----+\n|")
for j in 1:size, i in 1:size
ppuz(i,j)
if i == size
print("\n")
if j < size
print("|")
end
end
end
println("+----+----+----+----+")

end

function puzzle15play()
solved() = (puzzle[1:15] == string.(1:15))
shufflepuzzle()
println("This puzzle is", issolvable() ? " " : " not ", "solvable.")
while !solved()
printboard()
print("Possible moves are: \$(possiblemoves()), 0 to exit. Your move? =>  ")
if s == "0"
exit(0)
end
movehole(s)
end
printboard()
println("Puzzle solved.")
end

puzzle15play()
```
Output:
```
This puzzle is solvable.
+----+----+----+----+
| 5  | 7  | 14 |    |
| 4  | 3  | 13 | 12 |
| 10 | 1  | 6  | 9  |
| 8  | 15 | 11 | 2  |
+----+----+----+----+
Possible moves are: ["14", "12"], 0 to exit. Your move? =>  12
+----+----+----+----+
| 5  | 7  | 14 | 12 |
| 4  | 3  | 13 |    |
| 10 | 1  | 6  | 9  |
| 8  | 15 | 11 | 2  |
+----+----+----+----+
Possible moves are: ["13", "12", "9"], 0 to exit. Your move? =>

```

## Kotlin

Translation of: Java
```// version 1.1.3

import java.awt.BorderLayout
import java.awt.Color
import java.awt.Dimension
import java.awt.Font
import java.awt.Graphics
import java.awt.Graphics2D
import java.awt.RenderingHints
import java.awt.event.MouseEvent
import java.util.Random
import javax.swing.JFrame
import javax.swing.JPanel
import javax.swing.SwingUtilities

class FifteenPuzzle(dim: Int, val margin: Int) : JPanel() {

private val rand = Random()
private val tiles = IntArray(16)
private val tileSize = (dim - 2 * margin) / 4
private val gridSize = tileSize * 4
private var blankPos = 0

init {
preferredSize = Dimension(dim, dim)
background = Color.white
val cornflowerBlue = 0x6495ED
foreground = Color(cornflowerBlue)
font = Font("SansSerif", Font.BOLD, 60)

override fun mousePressed(e: MouseEvent) {
val ex = e.x - margin
val ey = e.y - margin
if (ex !in 0..gridSize || ey !in 0..gridSize) return

val c1 = ex / tileSize
val r1 = ey / tileSize
val c2 = blankPos % 4
val r2 = blankPos / 4
if ((c1 == c2 && Math.abs(r1 - r2) == 1) ||
(r1 == r2 && Math.abs(c1 - c2) == 1)) {
val clickPos = r1 * 4 + c1
tiles[blankPos] = tiles[clickPos]
tiles[clickPos] = 0
blankPos = clickPos
}
repaint()
}
})

shuffle()
}

private fun shuffle() {
do {
reset()
// don't include the blank space in the shuffle,
// leave it in the home position
var n = 15
while (n > 1) {
val r = rand.nextInt(n--)
val tmp = tiles[r]
tiles[r] = tiles[n]
tiles[n] = tmp
}
} while (!isSolvable())
}

private fun reset() {
for (i in 0 until tiles.size) {
tiles[i] = (i + 1) % tiles.size
}
blankPos = 15
}

/*  Only half the permutations of the puzzle are solvable.

Whenever a tile is preceded by a tile with higher value it counts
as an inversion. In our case, with the blank space in the home
position, the number of inversions must be even for the puzzle
to be solvable.
*/

private fun isSolvable(): Boolean {
var countInversions = 0
for (i in 0 until 15) {
(0 until i)
.filter { tiles[it] > tiles[i] }
.forEach { countInversions++ }
}
return countInversions % 2 == 0
}

private fun drawGrid(g: Graphics2D) {
for (i in 0 until tiles.size) {
if (tiles[i] == 0) continue

val r = i / 4
val c = i % 4
val x = margin + c * tileSize
val y = margin + r * tileSize

with(g) {
color = foreground
fillRoundRect(x, y, tileSize, tileSize, 25, 25)
color = Color.black
drawRoundRect(x, y, tileSize, tileSize, 25, 25)
color = Color.white
}
drawCenteredString(g, tiles[i].toString(), x, y)
}
}

private fun drawCenteredString(g: Graphics2D, s: String, x: Int, y: Int) {
val fm = g.fontMetrics
val asc = fm.ascent
val des = fm.descent

val xx = x + (tileSize - fm.stringWidth(s)) / 2
val yy = y + (asc + (tileSize - (asc + des)) / 2)

g.drawString(s, xx, yy)
}

override fun paintComponent(gg: Graphics) {
super.paintComponent(gg)
val g = gg as Graphics2D
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON)
drawGrid(g)
}
}

fun main(args: Array<String>) {
SwingUtilities.invokeLater {
val f = JFrame()
with(f) {
defaultCloseOperation = JFrame.EXIT_ON_CLOSE
title = "Fifteen Puzzle"
isResizable = false
pack()
setLocationRelativeTo(null)
isVisible = true
}
}
}
```

## Liberty BASIC

Translation of: Commodore BASIC
Works with: Just BASIC
```' 15-PUZZLE GAME
' ********************************
dim d(16)
dim ds\$(16) ' Board pieces
dim sh(3)

call buildBoard introAndLevel()
call printPuzzle
do
print "To move a piece, enter its number: "
input x
while isMoveValid(x, y, z) = 0
print "Wrong move."
call printPuzzle
print "To move a piece, enter its number: "
input x
wend
d(z) = x
d(y) = 0
call printPuzzle
loop until isPuzzleComplete()
print "YOU WON!"
end

sub printPuzzle
for p = 1 to 16
if d(p) = 0 then
ds\$(p) = "     "
else
ds\$(p) = using("###", d(p)) + "  "
end if
next p
print "+-----+-----+-----+-----+"
print "|"; ds\$(1); "|"; ds\$(2); "|"; ds\$(3); "|"; ds\$(4); "|"
print "+-----+-----+-----+-----+"
print "|"; ds\$(5); "|"; ds\$(6); "|"; ds\$(7); "|"; ds\$(8); "|"
print "+-----+-----+-----+-----+"
print "|"; ds\$(9); "|"; ds\$(10); "|";ds\$(11); "|"; ds\$(12); "|"
print "+-----+-----+-----+-----+"
print "|"; ds\$(13); "|"; ds\$(14); "|"; ds\$(15); "|"; ds\$(16); "|"
print "+-----+-----+-----+-----+"
end sub

function introAndLevel()
cls
sh(1) = 10
sh(2) = 50
sh(3) = 100
print "15 PUZZLE GAME"
print
print
print "Please enter level of difficulty,"
do
print "1 (easy), 2 (medium) or 3 (hard): ";
input level
loop while (level < 1) or (level > 3)
introAndLevel = level
end function

sub buildBoard level
' Set pieces in correct order first
for p = 1 to 15
d(p) = p
next p
d(16) = 0 ' 0 = empty piece/slot
z = 16 ' z = empty position
print
print "Shuffling pieces";
for n = 1 to sh(level)
print ".";
do
x = int(rnd(0) * 4) + 1
select case x
case 1
r = z - 4
case 2
r = z + 4
case 3
if (z - 1) mod 4 <> 0 then
r = z - 1
end if
case 4
if z mod 4 <> 0 then
r = z + 1
end if
end select
loop while (r < 1) or (r > 16)
d(z) = d(r)
z = r
d(z) = 0
next n
cls
end sub

function isMoveValid(piece, byref piecePos, byref emptyPos)
mv = 0
if (piece >= 1) and (piece <= 15) then
piecePos = piecePosition(piece)
emptyPos = piecePosition(0)
' Check if empty piece is above, below, left or right to piece
if (piecePos - 4 = emptyPos) or _
(piecePos + 4 = emptyPos) or _
((piecePos - 1 = emptyPos) and (emptyPos mod 4 <> 0)) or _
((piecePos + 1 = emptyPos) and (piecePos mod 4 <> 0)) then
mv = 1
end if
end if
isMoveValid = mv
end function

function piecePosition(piece)
p = 1
while d(p) <> piece
p = p + 1
if p > 16 then
print "UH OH!"
stop
end if
wend
piecePosition = p
end function

function isPuzzleComplete()
pc = 0
p = 1
while (p < 16) and (d(p) = p)
p = p + 1
wend
if p = 16 then
pc = 1
end if
isPuzzleComplete = pc
end function```

## LiveCode

```#Please note that all this code can be performed in livecode with just few mouse clicks
#This is just a pure script exampe
on OpenStack
show me  #Usually not necessary
#tile creation
set the width of the templateButton to 50
set the height of the templateButton to 50
repeat with i=1 to 16
create button
set the label of  button i to i
if i =1 then
set the top of button 1 to 0
set the left of button 1 to 0
end if
if i > 1 and 1 <=4  then
set the left of button i to the right of button (i-1)
set the top of button i to the top of button 1
end if
if i >= 5 and i <= 8 then
set the top of button i to the bottom of button 1
if i = 5 then
set the left of button i to the left of button 1
else
set the left of button i to the right of button (i - 1)
end if
end if
if i >= 9 and i <= 12 then
set the top of button i to the bottom of button 5
if i = 9 then
set the left of button i to the left of button 1
else
set the left of button i to the right of button (i - 1)
end if
end if
if i >= 13 and i <= 16 then
set the top of button i to the bottom of button 9
if i = 13 then
set the left of button i to the left of button 1
else
set the left of button i to the right of button (i - 1)
end if
end if
#this is usally the script directly wirtten in the objects, it's really weird this way
put "on MouseUp" &CR& "if checkDistance(the label of me) then" & CR &"put the loc of me into temp" into ts
put CR& "set the loc of me to the loc of button 16" after ts
put CR& "set the loc of button 16 to temp" & Cr & "end if " &CR &"End MouseUp" after ts
set the script of button i to ts
end repeat
set the visible of button 16 to false
set the width of this stack to the right of button 16
set the height of this stack to the bottom of button 16
end openStack

function checkDistance i
if (((the top of button i - the bottom of button 16) = 0 OR (the top of button 16 - the bottom of button i) = 0) AND the left of button i = the left of button 16) OR (((the left of button i - the right of button 16) = 0 OR (the right of button i - the left of button 16) = 0) AND the top of button i = the top of button 16) then
return true
else
return false
end if
end checkDistance```

Screenshot: [2]

## Lua

```math.randomseed( os.time() )
local puz = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0 }
local dir = { { 1, 0 }, { -1, 0 }, { 0, 1 }, { 0, -1 } }
local sx, sy = 4, 4

function isValid( tx, ty )
return tx > 0 and tx < 5 and ty > 0 and ty < 5
end
function display()
io.write( "\n\n" )
for j = 1, 4 do
io.write( "+----+----+----+----+\n" )
for i = 1, 4 do
local d = puz[i + j * 4 - 4]
io.write( ": " )
if d < 10 then io.write( " " ) end
if d < 1  then
io.write( "  " )
else
io.write( string.format( "%d ", d ) )
end
end
io.write( ":\n" )
end
io.write( "+----+----+----+----+\n\n" )
end
function getUserNove()
local moves, r, tx, ty = {}
for d = 1, 4 do
tx = sx; ty = sy
tx = tx + dir[d][1]; ty = ty + dir[d][2]

if isValid( tx, ty ) then
table.insert( moves, puz[tx + ty * 4 - 4] )
end
end

io.write( "Your possible moves are: " )
for i = 1, #moves do
io.write( string.format( "%d ", moves[i] ) )
end

if r ~= nil then
for i = 1, #moves do
if moves[i] == r then return r end
end
end
print( "Invalid move!" )
return -1
end
function checked( r )
for i = 1, #puz do
if puz[i] == r then
puz[i] = 0
sx = 1 + ( i - 1 ) % 4; sy = math.floor( ( i + 3 ) / 4 )
elseif puz[i] == 0 then
puz[i] = r
end
end
for i = 2, #puz - 1 do
if puz[i - 1] + 1 ~= puz[i] then return false end
end
return true
end
function beginGame()
local r, d, tx, ty
while( true ) do
for i = 1, 100 do
while( true ) do
tx = sx; ty = sy; d = math.random( 4 )
tx = tx + dir[d][1]; ty = ty + dir[d][2]
if isValid( tx, ty ) then break end
end
puz[sx + sy * 4 - 4] = puz[tx + ty * 4 - 4]
puz[tx + ty * 4 - 4] = 0; sx = tx; sy = ty
end
while( true ) do
display(); r = getUserNove()
if r > 0 then
if checked( r ) then
display()
io.write( "\nDone!\n\nPlay again (Y/N)?" )
if r ~= "Y" and r ~= "y" then
return
else
break
end
end
end
end
end
end
-- [ entry point ] --
beginGame()
```
Output:
```+----+----+----+----+
:  1 : 15 :  7 :  3 :
+----+----+----+----+
: 14 :  9 :  2 :  4 :
+----+----+----+----+
:  5 : 13 :    : 10 :
+----+----+----+----+
:  6 : 12 :  8 : 11 :
+----+----+----+----+

Your possible moves are: 10 13 8 2
```
Translation of: COMMODORE BASIC

## M2000 Interpreter

Translation of: COMMODORE BASIC

I make a function RND() and I set Base for arrays to 1 Also I put some semi colons to Print statement Also I have to put variables after NEXT statements To be actual BASIC compatible we have to set FOR NEXT like BASIC, because for M2000 the direction defined by the starting-ending values, so always we get at least one time the block between FOR NEXT. So we can use:

SET SWITCHES "+FOR"

But here we don't have to skip FOR NEXT and no STEP clause used.

Also the code is not the best, because we can move from 4 position to 5 (we can't do that with real puzzle)

```Module Puzzle15 {

00 BASE 1 : DEF RND(X)=RND
10 REM 15-PUZZLE GAME
20 REM COMMODORE BASIC 2.0
30 REM ********************************
40 GOSUB 400 : REM INTRO AND LEVEL
50 GOSUB 510 : REM SETUP BOARD
60 GOSUB 210 : REM PRINT PUZZLE
70 PRINT "TO MOVE A PIECE, ENTER ITS NUMBER:"
80 INPUT X
90 GOSUB 730 : REM CHECK IF MOVE IS VALID
100 IF MV=0 THEN PRINT "WRONG MOVE" : GOSUB 1050 : GOTO 60
110 D(Z)=X : D(Y)=0
120 GOSUB 210 : REM PRINT PUZZLE
130 GOSUB 950 : REM CHECK IF PUZZLE COMPLETE
140 IF PC THEN 160
150 GOTO 70
160 PRINT"YOU WON!"
170 END
180 REM
190 REM *******************************
200 REM PRINT/DRAW THE PUZZLE
210 FOR P=1 TO 16
220   IF D(P)=0 THEN D\$(P)="     " : GOTO 260
230   S\$=STR\$(D(P))
240   N=LEN(S\$)
250   D\$(P) = LEFT\$("   ",3-N)+S\$+"  "
260 NEXT P
270 PRINT "+-----+-----+-----+-----+"
280 PRINT "!";D\$(1);"!";D\$(2);"!";D\$(3);"!";D\$(4);"!"
290 PRINT "+-----+-----+-----+-----+"
300 PRINT "!";D\$(5);"!";D\$(6);"!";D\$(7);"!";D\$(8);"!"
310 PRINT "+-----+-----+-----+-----+"
320 PRINT "!";D\$(9);"!";D\$(10);"!";D\$(11);"!";D\$(12);"!"
330 PRINT "+-----+-----+-----+-----+"
340 PRINT "!";D\$(13);"!";D\$(14);"!";D\$(15);"!";D\$(16);"!"
350 PRINT "+-----+-----+-----+-----+"
360 RETURN
370 REM
380 REM *******************************
390 REM INTRO AND LEVEL OF DIFFICULTY
400 PRINT CHR\$(147)
410 DIM SH(3) : SH(1)=10 : SH(2)=50 : SH(3)=100
420 PRINT "15 PUZZLE GAME FOR COMMODORE BASIC 2.0" : PRINT : PRINT
430 PRINT "PLEASE ENTER LEVEL OF DIFFICULTY,"
440 PRINT "1(EASY), 2(MEDIUM) OR 3(HARD):";
450 INPUT V
460 IF V<1 OR V>3 THEN 440
470 RETURN
480 REM
490 REM *******************************
500 REM BUILD THE BOARD
510 DIM D(16) : DIM D\$(16) : REM BOARD PIECES
520 REM SET PIECES IN CORRECT ORDER FIRST
530 FOR P=1 TO 15
540   D(P) = P
550 NEXT P
560 D(16) = 0 : REM 0 = EMPTY PIECE/SLOT
570 Z=16      : REM Z = EMPTY POSITION
580 PRINT: PRINT "SHUFFLING PIECES";
590 FOR N=1 TO SH(V)
600   PRINT".";
610   X = INT(RND(0)*4)+1
620   R = Z+(X=1)*4-(X=2)*4+(X=3)-(X=4)
630   IF R<1 OR R>16 THEN 610
640   D(Z)=D(R)
650   Z=R
660   D(Z)=0
670 NEXT N
680 PRINT CHR\$(147)
690 RETURN
700 REM
710 REM *******************************
720 REM CHECK IF MOVE IS VALID
730 MV = 0
740 IF X<1 OR X>15 THEN RETURN
750 REM FIND POSITION OF PIECE X
760 P=1
770 IF D(P)=X THEN Y=P : GOTO 810
780 P=P+1 : IF P>16 THEN PRINT "UH OH!" : STOP
790 GOTO 770
800 REM FIND POSITION OF EMPTY PIECE
810 P=1
820 IF D(P)=0 THEN Z=P : GOTO 860
830 P=P+1 : IF P>16 THEN PRINT "UH OH!" : STOP
840 GOTO 820
850 PRINT Y;Z
860 REM CHECK IF EMPTY PIECE IS ABOVE, BELOW, LEFT OR RIGHT TO PIECE X
870 IF Y-4=Z THEN MV=1 : RETURN
880 IF Y+4=Z THEN MV=1 : RETURN
890 IF Y-1=Z THEN MV=1 : RETURN
900 IF Y+1=Z THEN MV=1 : RETURN
910 RETURN
920 REM
930 REM *******************************
940 REM CHECK IF PUZZLE IS COMPLETE / GAME OVER
950 PC = 0
960 P=1
970 IF D(P)<>P THEN RETURN
980 P=P+1
990 IF P<16 THEN 970
1000 PC = 1
1010 RETURN
1020 REM
1030 REM ******************************
1040 REM A SMALL DELAY
1050 FOR T=0 TO 400
1060 NEXT T
1070 RETURN
}
Puzzle15```

## Mathematica / Wolfram Language

```grid = MapThread[{#1,#2} &, {Range @ 16, Range @ 16}]

Move[x_] := (empty = Select[grid, #[[1]]==16 &][[1,2]];
If[(empty == x+4) || (empty == x-4) ||
(Mod[empty,4] != 0 && empty == x-1) ||
(Mod[empty,4] != 1 &&<```