Q06_towers_of_hanoi.py

import unittest


def towers_of_hanoi(origin, destination, buffer, n=None):
    if n is None:
        n = len(origin.discs)
    if n == 0:
        return
    towers_of_hanoi(origin, buffer, destination, n - 1)
    disc = origin.discs.pop()
    buffer.discs.append(disc)
    towers_of_hanoi(destination, origin, buffer, n - 1)


class Tower(object):
    def __init__(self, name, discs=None):
        self.name = name
        if discs:
            self.discs = discs
        else:
            self.discs = []

    def __str__(self):
        return self.name


class Test(unittest.TestCase):
    def test_towers_of_hanoi(self):
        tower1 = Tower("Tower1", ["6", "5", "4", "3", "2", "1"])
        tower2 = Tower("Tower2")
        tower3 = Tower("Tower3")
        towers_of_hanoi(tower1, tower2, tower3)
        self.assertEqual(tower1.discs, [])
        self.assertEqual(tower2.discs, [])
        self.assertEqual(tower3.discs, ["6", "5", "4", "3", "2", "1"])