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