Sort of a stack with two stacks using insertion sort

gistfile1.py

#!/usr/bin/env python

from collections import deque

# Sort using insertion sort with stacks O(n^2)
def sort_stack(l):
	res_stack = deque()
	
	# We keep res_stack always sorted
	while len(l) > 0:
		current = l.pop()
		
		while True:
			if len(res_stack) == 0:
				res_stack.append(current)
				break
			
			elem = res_stack.pop()
			if elem <= current:
				res_stack.append(elem)
				res_stack.append(current)
				break
			else:
				l.append(elem)
	
	return res_stack

print sort_stack(deque([1, 5, -1, 6, 0]))