Recursive Postorder Traversal

Given a binary tree, write a method to populate the list Arraylist <Integer> postorderedList with the nodes of the tree in postorder, recursively.

Example:  
     1
    / \
   2   3     ==> 4526731
  / \ / \
 4  5 6  7

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

Quick hint to get things rolling

Post-order traversal
1. Traverse the left subtree by recursively calling the postorder function.
2. Traverse the right subtree by recursively calling the postorder function.
3. Add the data part of root element(or current element) in the arraylist

A more detailed explanation

Use add method to add the node's data in the postorderedList list

Final hint! You should be able to code the problem on viewing this.

1. Starting with the root node, recurse through the left nodes. Data of the elements in the left subtree will get added to the ArrayList.

2. Recurse through the right nodes. Data of the elements in the right subtree will get added next into the ArrayList.

3. Add the data of the root nodes in the Array List then return from the method

//Populate the elements of the tree in the below list in the post order way.
ArrayList<Integer> postOrderedList = new ArrayList<Integer>();
public void postorder(TreeNode root) {
    



}

This Coding Interview Question is available with an answer in the following programming languages :

Java

Python

Recursive Postorder Traversal

Quick hint to get things rolling

A more detailed explanation

Final hint! You should be able to code the problem on viewing this.

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This Coding Interview Question is available with an answer in the following programming languages :