Towers of Hanoi: Python2 implementation both recursively and iteratively using a Python list as our stack. Note that the well-known iterative solution with O(1) space requirements is not included here.

toh.py

####################################
# Copyright Christopher Abiad, 2013
# All Rights Reserved
####################################

__author__ = 'Christopher Abiad'


def toh(num, src, dest, other):
    if num <= 0:
        return
    elif num == 1:
        print "move {s} to {d}".format(s=src, d=dest)
        return

    toh(num - 1, src, other, dest)
    print "move {s} to {d}".format(s=src, d=dest)
    toh(num - 1, other, dest, src)


def toh_iterative(num, src, dest, other):

    class Move(object):
        def __init__(self, num, src, dest, other):
            self.num = num
            self.src = src
            self.dest = dest
            self.other = other

    if num == 0:
        return

    work = [Move(num, src, dest, other)]

    while len(work) > 0:
        item = work.pop()
        if item.num == 1:
            print "move {s} to {d}".format(s=item.src, d=item.dest)
        else:
            # Append new work to do in reverse order
            # (first thing to do next is appended last)
            work.append(Move(item.num - 1, item.other, item.dest, item.src))
            work.append(Move(1, item.src, item.dest, item.other))
            work.append(Move(item.num - 1, item.src, item.other, item.dest))


if __name__ == '__main__':
    print "recursive solution:"
    toh(3, 's', 'd', 'o')
    print "\niterative solution:"
    toh_iterative(3, 's', 'd', 'o')