35 lines
1.2 KiB
Forth
35 lines
1.2 KiB
Forth
The Tower of Hanoi (also called the Tower of Brahma or Lucas' Tower
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and sometimes pluralized) is a mathematical game or puzzle. It
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consists of three rods and a number of disks of different sizes,
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which can slide onto any rod. The puzzle starts with the disks in
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a neat stack in ascending order of size on one rod, the smallest
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at the top, thus making a conical shape.
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The objective of the puzzle is to move the entire stack to another
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rod, obeying the following simple rules:
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- Only one disk can be moved at a time.
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- Each move consists of taking the upper disk from one of the
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stacks and placing it on top of another stack.
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- No disk may be placed on top of a smaller disk.
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With 3 disks, the puzzle can be solved in 7 moves. The minimal
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number of moves required to solve a Tower of Hanoi puzzle is
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2^n-1, where n is the number of disks.
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Taken from https://en.m.wikipedia.org/wiki/Tower_of_Hanoi
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~~~
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{ 'Num 'From 'To 'Via } [ var ] a:for-each
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:set !Via !To !From !Num ;
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:display @To @From 'Move_a_ring_from_%n_to_%n\n s:format s:put ;
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:hanoi (num,from,to,via-)
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set @Num n:-zero?
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[ @Num @From @To @Via
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@Num n:dec @From @Via @To hanoi set display
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@Num n:dec @Via @To @From hanoi ] if ;
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#3 #1 #3 #2 hanoi nl
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~~~
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