This is a programming exercise to solve the towers of hanoi puzzle. The physical puzzle has three pegs in a row. On the first peg is a stack of disks of descending diameter. You are only allowed to put a smaller disk on top of a larger disk, never the reverse. The task is to move the entire pile from the far left peg, to the far right peg. This …

hanoi.py

"""
This is a programming exercise to solve the towers of hanoi puzzle.
The physical puzzle has three pegs in a row. On the first peg is a
stack of disks of descending diameter. You are only allowed to put
a smaller disk on top of a larger disk, never the reverse. The task
is to move the entire pile from the far left peg, to the far right
peg.

This script accepts one input argument, n, for the number of disks.
"""

import sys

stack1 = range(int(sys.argv[1]),0,-1)
stack2 = []
stack3 = []

def move_stack(source_stack, source_position, dest_stack, transit_stack):
    if len(source_stack) > source_position + 1:
        move_stack(source_stack, source_position + 1, transit_stack, dest_stack)

    element = source_stack.pop()
    dest_stack.append(element)
    print_status()

    if element == 1:
        return

    move_stack(transit_stack, transit_stack.index(element - 1), dest_stack, source_stack)

def print_status():
    print str(stack1)
    print str(stack2)
    print str(stack3) + "\n"

print_status()
move_stack(stack1, 0, stack3, stack2)
print "Done!"