July 23, 06 The classic Tower of Hanoi puzzle, updated with user-selectable graphic images like the Eiffel Tower, the Washington Monument, and the Space Shuttle (eleven in all) of varying difficulty. Can you solve the full 8-disk puzzle? In how many moves?

Beautiful photographs make this old puzzle a new experience for a new generation. Created in 1883 by Edouard Lucas, a French mathematician, the Tower of Hanoi has been used for decades to teach computer science students about recursive functions and relations.



Requirements: This application was developed in OS X 10.2 (Jaguar), but should be compatible with both 10.3 (Panther) and 10.4 (Tiger).

The game itself is simple: Move a stack of pieces from one stack to another using only a third stack and never placing a larger numbered piece on a smaller one. With a 2 piece stack you can do it in 3 moves. How many moves does it take to move a full 8 piece stack? Try 2 to the 8th power minus 1! Can you remember the sequence (once you find it) and not make a mistake?

Featured in Univers Mac, the French-language edition of Macworld.

NOTE:I wanted to alert Panther users to a potential problem. I have found that there is a bug in the Panther (OS X 10.3.9) version of AppleScript Studio that will cause a crash if you use AutoPlay with an 8-piece stack. The reasons are technical, but essentially it is caused by an illegal memory access that is outside my control. I've submitted a bug report to Apple.

For now, you can autoplay smaller stacks (7 still works for me), just not 8 pieces. You can, however, still manually play a full stack.

Great lesson in recursive programming for students. Includes commented AppleScript Studio source code, discussion of recursive "auto play" option and instructions for turning your own photos into game pieces.

Tower of Hanoi is a free download from your friends at GeekSuit.