Basic Pascal Tutorial/Chapter 4/Solution: what changed
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Title: Basic Pascal Tutorial/Chapter 4/Solution
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|---|---|---|---|
| 1 | + | 4Ga - Solution to Towers of Hanoi (author: Tao Yue, state: unchanged) | |
| 2 | + | ||
| 3 | + | ``` pascal | |
| 4 | + | (* Author: Tao Yue | |
| 5 | + | Date: 13 July 2000 | |
| 6 | + | Description: | |
| 7 | + | Solves the Towers of Hanoi | |
| 8 | + | Version: | |
| 9 | + | 1.0 - original version | |
| 10 | + | *) | |
| 11 | + | ||
| 12 | + | program TowersofHanoi; | |
| 13 | + | ||
| 14 | + | var | |
| 15 | + | numdiscs : integer; | |
| 16 | + | ||
| 17 | + | (********************************************************) | |
| 18 | + | ||
| 19 | + | procedure DoTowers (NumDiscs, OrigPeg, NewPeg, TempPeg : integer); | |
| 20 | + | (* Explanation of variables: | |
| 21 | + | Number of discs -- number of discs on OrigPeg | |
| 22 | + | OrigPeg -- peg number of the tower | |
| 23 | + | NewPeg -- peg number to move the tower to | |
| 24 | + | TempPeg -- peg to use for temporary storage | |
| 25 | + | *) | |
| 26 | + | ||
| 27 | + | begin | |
| 28 | + | (* Take care of the base case -- one disc *) | |
| 29 | + | if NumDiscs = 1 then | |
| 30 | + | writeln (OrigPeg, ' ---> ', NewPeg) | |
| 31 | + | (* Take care of all other cases *) | |
| 32 | + | else | |
| 33 | + | begin | |
| 34 | + | (* First, move all discs except the bottom disc | |
| 35 | + | to TempPeg, using NewPeg as the temporary peg | |
| 36 | + | for this transfer *) | |
| 37 | + | DoTowers (NumDiscs-1, OrigPeg, TempPeg, NewPeg); | |
| 38 | + | (* Now, move the bottommost disc from OrigPeg | |
| 39 | + | to NewPeg *) | |
| 40 | + | writeln (OrigPeg, ' ---> ', NewPeg); | |
| 41 | + | (* Finally, move the discs which are currently on | |
| 42 | + | TempPeg to NewPeg, using OrigPeg as the temporary | |
| 43 | + | peg for this transfer *) | |
| 44 | + | DoTowers (NumDiscs-1, TempPeg, NewPeg, OrigPeg) | |
| 45 | + | end | |
| 46 | + | end; | |
| 47 | + | ||
| 48 | + | (********************************************************) | |
| 49 | + | ||
| 50 | + | begin (* Main *) | |
| 51 | + | write ('Please enter the number of discs in the tower ===> '); | |
| 52 | + | readln (numdiscs); | |
| 53 | + | writeln; | |
| 54 | + | DoTowers (numdiscs, 1, 3, 2) | |
| 55 | + | end. (* Main *) | |
| 56 | + | ``` | |
| 57 | + | ||
| 58 | + | --- | |
| 59 | + | *From the Free Pascal wiki, page "Basic Pascal Tutorial/Chapter 4/Solution", as it stood on 2022-08-20 after a change by Kai Burghardt, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).* |