Trees: Iterative Post-order traversal using two stacks

Problem Statement:
       Perform post-order traversal using two stacks for the given binary tree.

Output: 
Post-order :  8 , 4 , 5 , 2 , 6 , 9 , 7 , 3 , 1

Solution:
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By post-order traversal I mean , process the Left Node ,then Right Node, and then Node all this processing happens in Depth First Search fashion. I assume that you know the recursive way to iterate a binary tree.

Pre-order Traversal : Node, Left Node, Right Node   -  +AB
In-order Traversal : Left Node, Node , Right Node      -  A+B
Post-order Traversal: Left Node, Right Node, Node   -  AB+

Iterative Traversal can also be done by Morris traversal , which uses the concept of Threaded Binary Trees.
Here we are performing iteration using two Stacks, also refer to my post using single stack.

Below is the implementation:

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/** * Iterative Pre-order traversal using two stacks */ public void iterativePostOrder(Node root) { Stack<Node> processed = new Stack<Node>(); Stack<Node> current = new Stack<Node>(); current.push(root); while(!current.isEmpty()) { Node item = current.pop(); processed.push(item); if(item.left!=null) current.push(item.left); if(item.right!=null) current.push(item.right); } while(!processed.isEmpty()) { System.out.print(processed.pop() + "\t"); } }

Please post your suggestions and comments.
Happy Coding !! :)