10 DEFINT A-Z
20 DIM P(2,7),S(3,16)
30 GOSUB 1000
40 GOSUB 1100:GOSUB 1200:GOSUB 1300
50 GOTO 40
1000 SCREEN 0,0:CLS:PRINT "Towers of Hanoi":RETURN
1100 PRINT @240,"How many disks (ENTER TO EXIT)? ";
1110 C$=INPUT$(1)
1120 IF C$=CHR$(13) THEN PRINT:PRINT:MENU
1130 IF C$<"1" OR C$>"7" THEN 1100
1140 PRINT C$;:N=ASC(C$)-48
1150 RETURN
1200 CLS:GOSUB 1000:T=40-3*N
1215 LINE (40,T+1)-(40,40),1
1220 LINE (120,T+1)-(120,40),1
1225 LINE (200,T+1)-(200,40),1
1230 LINE(0,41)-(239,44),1,BF
1235 P(0,0)=40:P(1,0)=120:P(2,0)=200
1240 D=1:C=40:FOR I=1 TO N:R=41-3*I:S=N+1-I:GOSUB 2000:P(0,I)=S:P(1,I)=0:P(2,I)=0:NEXT I
1250 MV=0
1260 RETURN
1300 S(0,0)=N:S(1,0)=0:S(2,0)=1:S(3,0)=2:IS=0
1305 IF IS<0 THEN RETURN
1310 IF S(0,IS)=1 THEN GOSUB 2100:IS=IS-1:GOTO 1305
1320 S(0,IS+2)=S(0,IS)-1:S(1,IS+2)=S(1,IS):S(2,IS+2)=S(3,IS):S(3,IS+2)=S(2,IS)
1325 S(0,IS+1)=1:S(1,IS+1)=S(1,IS):S(2,IS+1)=S(2,IS)
1330 S(0,IS)=S(0,IS)-1:S(1,IS)=S(3,IS):S(3,IS)=S(1,IS+1)
1335 IS=IS+2:GOTO 1310
2000 L=5*S
2010 LINE(C-L-1,R)-(C-2,R+1),D,BF
2020 LINE(C+2,R)-(C+L+1,R+1),D,BF
2030 RETURN
2100 P1=S(1,IS):P2=S(2,IS)
2110 FOR I=N TO 1 STEP -1
2120 IF P(P1,I)<>0 THEN 2140
2130 NEXT I
2140 S=P(P1,I):C1=P(P1,0):C2=P(P2,0):C=C1:P(P1,I)=0
2150 FOR J=38-3*I TO T-2 STEP -3
2160 R=J:D=1:GOSUB 2000:R=J+3:D=0:GOSUB 2000
2170 NEXT J
2180 R=T-2:L=5*S:D=1
2190 IF C1<C2 THEN K=1 ELSE K=-1
2200 FOR C=C1+2*K TO C2 STEP 2*K
2210 LINE(C-2,R)-(C+2,R+1),0,BF
2212 IC=C-K*(11+L):IF IC<0 THEN IC=0
2213 IF IC>239 THEN IC=239
2215 LINE(IC,R)-(C-K*(1+L),R+1),0,BF
2220 GOSUB 2000
2230 NEXT C
2240 FOR I=1 TO N
2250 IF P(P2,I)=0 THEN 2270
2260 NEXT I
2270 P(P2,I)=S:C=C2
2280 FOR J=T+1 TO 41-3*I STEP 3
2290 R=J:D=1:GOSUB 2000:R=J-3:D=0:GOSUB 2000:NEXT J
2300 MV=MV+1:PRINT @280,"Move: ";:PRINT USING "####";MV;
2310 RETURN