Anonymous user
Towers of Hanoi: Difference between revisions
→{{header|COBOL}}
m (→{{header|Retro}}: update for retro12) |
|||
Line 891:
.
END PROGRAM move-disk.
</lang>
=== ANSI-74 solution ===
Early versions of COBOL did not have recursion. There are no locally-scoped variables and the call of a procedure does not have to use a stack to save return state. Recursion would cause undefined results. It is therefore necessary to use an iterative algorithm. This solution is an adaptation of [http://hanoitower.mkolar.org/algo.html Kolar's Hanoi Tower algorithm no. 1].
{{works with|CIS COBOL|4.2}}{{works with|GnuCOBOL|3.0-rc1.0}}
<lang cobol> IDENTIFICATION DIVISION.
PROGRAM-ID. ITERATIVE-TOWERS-OF-HANOI.
AUTHOR. SOREN ROUG.
DATE-WRITTEN. 2019-06-28.
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SOURCE-COMPUTER. LINUX.
OBJECT-COMPUTER. KAYPRO4.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
DATA DIVISION.
WORKING-STORAGE SECTION.
77 NUM-DISKS PIC 9 VALUE 4.
77 N1 PIC 9 COMP.
77 N2 PIC 9 COMP.
77 FROM-POLE PIC 9 COMP.
77 TO-POLE PIC 9 COMP.
77 VIA-POLE PIC 9 COMP.
77 FP-TMP PIC 9 COMP.
77 TO-TMP PIC 9 COMP.
77 P-TMP PIC 9 COMP.
77 TMP-P PIC 9 COMP.
77 I PIC 9 COMP.
77 DIV PIC 9 COMP.
01 STACKNUMS.
05 NUMSET OCCURS 3 TIMES.
10 DNUM PIC 9 COMP.
01 GAMESET.
05 POLES OCCURS 3 TIMES.
10 STACK OCCURS 10 TIMES.
15 POLE PIC 9 USAGE COMP.
PROCEDURE DIVISION.
HANOI.
DISPLAY "TOWERS OF HANOI PUZZLE WITH ", NUM-DISKS, " DISKS.".
ADD NUM-DISKS, 1 GIVING N1.
ADD NUM-DISKS, 2 GIVING N2.
MOVE 1 TO DNUM (1).
MOVE N1 TO DNUM (2), DNUM (3).
MOVE N1 TO POLE (1, N1), POLE (2, N1), POLE (3, N1).
MOVE 1 TO POLE (1, N2).
MOVE 2 TO POLE (2, N2).
MOVE 3 TO POLE (3, N2).
MOVE 1 TO I.
PERFORM INIT-PUZZLE UNTIL I = N1.
MOVE 1 TO FROM-POLE.
DIVIDE 2 INTO NUM-DISKS GIVING DIV.
MULTIPLY 2 BY DIV.
IF DIV NOT = NUM-DISKS PERFORM INITODD ELSE PERFORM INITEVEN.
PERFORM MOVE-DISK UNTIL DNUM (3) NOT > 1.
DISPLAY "TOWERS OF HANOI PUZZLE COMPLETED!".
STOP RUN.
INIT-PUZZLE.
MOVE I TO POLE (1, I).
MOVE 0 TO POLE (2, I), POLE (3, I).
ADD 1 TO I.
INITEVEN.
MOVE 2 TO TO-POLE.
MOVE 3 TO VIA-POLE.
INITODD.
MOVE 3 TO TO-POLE.
MOVE 2 TO VIA-POLE.
MOVE-DISK.
MOVE DNUM (FROM-POLE) TO FP-TMP.
MOVE POLE (FROM-POLE, FP-TMP) TO I.
DISPLAY "MOVE DISK FROM ", POLE (FROM-POLE, N2),
" TO ", POLE (TO-POLE, N2).
ADD 1 TO DNUM (FROM-POLE).
MOVE VIA-POLE TO TMP-P.
SUBTRACT 1 FROM DNUM (TO-POLE).
MOVE DNUM (TO-POLE) TO TO-TMP.
MOVE I TO POLE (TO-POLE, TO-TMP).
DIVIDE 2 INTO I GIVING DIV.
MULTIPLY 2 BY DIV.
IF I NOT = DIV PERFORM MOVE-TO-VIA ELSE
PERFORM MOVE-FROM-VIA.
MOVE-TO-VIA.
MOVE TO-POLE TO VIA-POLE.
MOVE DNUM (FROM-POLE) TO FP-TMP.
MOVE DNUM (TMP-P) TO P-TMP.
IF POLE (FROM-POLE, FP-TMP) > POLE (TMP-P, P-TMP)
PERFORM MOVE-FROM-TO
ELSE MOVE TMP-P TO TO-POLE.
MOVE-FROM-TO.
MOVE FROM-POLE TO TO-POLE.
MOVE TMP-P TO FROM-POLE.
MOVE DNUM (FROM-POLE) TO FP-TMP.
MOVE DNUM (TMP-P) TO P-TMP.
MOVE-FROM-VIA.
MOVE FROM-POLE TO VIA-POLE.
MOVE TMP-P TO FROM-POLE.
</lang>
| |||