Solves towers of hannoi

hanoi.py

# coding=utf-8
'''
File: hanoi.py
Author: Sigurd Fosseng, Håkon Røkenes
Description: Solves towers of hanoi
http://en.wikipedia.org/wiki/Tower_of_Hanoi#Simpler_statement_of_iterative_solution
'''


def legal_move(m, n):
    if len(m) > 0 and len(n) > 0:
        if m[0] > n[0]:
            m.insert(0, n.pop(0))
        else:
            n.insert(0, m.pop(0))
    elif len(m) > 0:
        n.append(m.pop(0))
    else:
        m.append(n.pop(0))
    return (m, n)


def main():
    a = [1, 2, 3, 4, 5, 6, 7]
    b = []
    c = []

    pairs = len(a) % 2
    orig_num = len(a)
    if pairs == 0:
        while(len(c) != orig_num):
            a, b = legal_move(a, b)
            a, c = legal_move(a, c)
            b, c = legal_move(b, c)
    if pairs == 1:
        while(len(c) != orig_num):
            a, c = legal_move(a, b)
            a, b = legal_move(a, c)
            b, c = legal_move(b, c)
    print c

if __name__ == '__main__':
    main()