Find the Sum of all Elements in a Binary Tree Iteratively

Given a binary tree, write a method to find and return the sum of all nodes of the tree iteratively.

Example:  
       1
      / \
     2   3    
    / \ / \        
   4  5 6  7
  /
 8   
  ==> sum of all nodes = 36 
  (1+2+3+4+5+6+7+8)

Need a hand? Try out these hints, one at a time.

Use levelorder traversal to traverse the tree and increment a sum variable.

Use a Queue for levelorder traversal.

1. Declare a Queue to store the nodes of the tree.

2. Queue the root.

3. Loop while the queue is not empty.

4. Within the loop, dequeue a node and add its data to the overall sum. Queue the left and right children.

5. Return the sum outside the loop.

public int sumItr(TreeNode root) { 
    



}

Java

Python