90: Binary tree postorder traversal

Given a binary tree, return postorder traversal of the tree

Note: write the iterative solution, the recursive solution is trivial (see below)

public void PostorderTraversal(TreeNode root)
{
    if (root == null)
    {
        return;
    }
    PostorderTraversal(root.Left);
    PostorderTraversal(root.Right);
    Console.WriteLine(root.Value);
}

 

Example 1

Input:     1   
          / \  
         5   3 

Output: [5, 3, 1]

Example 2

Input:     1   
            \  
             3 

Output: [3, 1]