def post_order_iterative_one_stack(node):
if node == None:
return
stack1 = Stack()
stack1.push(node)
prev = None
while not stack1.is_empty():
curr = stack1.top()
if (prev == None or prev.right == curr or prev.left ==curr):
# go down the Tree
if curr.left != None:
stack1.push(curr.left)
elif curr.right != None:
stack1.push(curr.right)
else:
print stack1.pop()
elif curr.left == prev:
if curr.right != None:
stack1.push(curr.right)
else:
print stack1.pop()
elif curr.right == prev:
print stack1.pop()
prev = curr
