10 REM***THE FIFTEEN PUZZLE
20 REM***W. L. COLSHER
30 CLS:IN."DO YOU NEED INSTRUCTIONS (Y=1, N=2)";A:IF A=1 T.GOS.10000
40 CLS:M=0:P."GENERATING THE PUZZLE TAKES A WHILE. PLEASE WAIT."
50 F.I=1TO16:A(I)=0:N.I
60 F.I=1TO16
70 R=RND(16)
80 IFA(R)<>0T.70
90 A(R)=I
100 N.I
110 GOS.5000
120 IF F=1 T.50
130 GOS.6000
140 P." ":IN."YOUR MOVE";X
145 GOS.4000
150 GOS.7000
160 IF F<>0 T.180
170 P."ILLEGAL MOVE, RE-ENTER":F.I=1TO500:N.I:G.130
180 A(X+F)=A(X):A(X)=16
190 G.8000
200 M=M+1:G.130
999 END
4000 REM***C0NVERT NUMBER TO LOCATION IN ARRAY
4010 F.I=1TO16
4020 IFA(I)=X T.4040
4030 N.I
4040 X=I
4050 RET.
5000 REM***VERIFY SOLUTION POSSIBLE
5005 F=1
5010 S-0
5020 F.I=1to15
5030 F.J=I+1TO16
5040 IFA(I)>A(J)T.S=S+1
5050 N.J:N.I
5060 F.I=1TO8
5070 READ X
5080 IF A(X)=0 T. S-S+1
5090 N.I
5095 REST.
5100 A=INT(S/2)
5110 IFA*2=S T. F=0
5120 RET.
5130 DATA 2,4,5,7,10,12,13,15
6000 REM***FISPLAY GAME BOARD
6005 C.:L=339:P.A.217,"MOVE ";M
6010 F.I=1TO4
6015 P.A.L," ";
6020 F.J=1TO4
6025 N=A((I-1)*4+J)
6028 IF N=16 T. N=0
6030 IF N<10 T.P." ";N;
6038 IF (N=10) * (N>16) T.P.N;
6040 N.J
6050 L=L+64
6060 N.I
6070 RET.
7000 REM***CHECK FOR LEGAL MOVE
7010 F=0
7015 IFX+1>16T.7025
7020 IFA(X+1)*16T.F=1
7025 IFX-1>=0T.7035
7030 IFA(X-1)=16T.F=-1
7035 IFX+4>16T.7045
7040 IFA(X+4)=16T.F=4
7045 IFX-4<=0T.7060
7050 IFA(X-4)=16T.F=-4
7060 RET.
8000 REM***CHECK FOR A WIN 
8010 F.I=1TO16
8020 IFA(I)<>I T.200
8030 N.I
8040 GOS.6000
8050 P." ":P." "
8060 P."CONGRATULATIONS!!! YOU DID IT IN ONLY ";M;" MOVES!!"
8070 P." ":IN."TO PLAY AGAIN, HIT ENTER. ";A$
8090 G.10
10000 REM***INSTRUCTIONS
10010 C.:P.A.18,"F I F T E E N   P U Z Z L E"
10020 P.A.128,"THE OBJECT OF THE 'FIFTEEN PUZZLE IS TO MOVE THE"
10030 P."NUMBERS AROUND SO THAT THEY ARE IN ORDER FROM 1 TO 15. A MOVE"
10040 P."IS MADE BY TYPING IN THE NUMBER (WHICH MUST BE ADJACENT TO"
10050 P."THE ZERO) YOU WISH TO MOVE. THAT NUMBER IS THEN EXCHANGED"
10060 P."WITH THE ZERO.  YOU WIN WHEN THE BOARD LOOKS LIKE THIS:"
10070 P." ":P." ":P." 1  2  3  4":P." 5  6  7  8":P." 9 10 11 12"
10080 P."13 14 15 0"
10090 P." ":IN."HIT ENTER TO PLAY";A$
10100 RET.