Tree Traversal Postorder Left Right Root in DSA Javascript - Build from Scratch

Tree Traversal Postorder Left Right Root

📖 Scenario: You are working with a simple family tree where each person can have up to two children. You want to visit all family members in a special order: first the left child, then the right child, and finally the parent. This order is called postorder traversal.

🎯 Goal: Build a program that creates a small tree, sets up a function to visit nodes in postorder (left, right, root), and prints the names of family members in that order.

📋 What You'll Learn

Create a tree node structure with name, left, and right properties

Build a small tree with exactly three nodes: 'Grandpa' as root, 'Dad' as left child, and 'Uncle' as right child

Write a function called postorderTraversal that visits nodes in left-right-root order

Print the names of the nodes in the order they are visited

💡 Why This Matters

🌍 Real World

Tree traversal is used in many areas like file system navigation, organizing family trees, and evaluating expressions.

💼 Career

Understanding tree traversal is important for software engineers working with hierarchical data, databases, and algorithms.

1

Create the tree nodes

Create three variables called grandpa, dad, and uncle. Each should be an object with a name property set to 'Grandpa', 'Dad', and 'Uncle' respectively, and left and right properties set to null.

DSA Javascript

// Your code here

Hint

Use object literals with name, left, and right keys.

2

Link the nodes to form the tree

Set the left property of grandpa to dad and the right property of grandpa to uncle.

DSA Javascript

const grandpa = { name: 'Grandpa', left: null, right: null };
const dad = { name: 'Dad', left: null, right: null };
const uncle = { name: 'Uncle', left: null, right: null };

// Your code here

Hint

Assign the dad and uncle objects to the left and right properties of grandpa.

3

Write the postorder traversal function

Write a function called postorderTraversal that takes a node as input. It should recursively visit the left child, then the right child, and finally print the name of the current node.

DSA Javascript

const grandpa = { name: 'Grandpa', left: null, right: null };
const dad = { name: 'Dad', left: null, right: null };
const uncle = { name: 'Uncle', left: null, right: null };

grandpa.left = dad;
grandpa.right = uncle;

// Your code here

Hint

Use recursion to visit left, then right, then print the node's name.

4

Run the traversal and print output

Call postorderTraversal with grandpa as the argument to print the names in postorder.

DSA Javascript

const grandpa = { name: 'Grandpa', left: null, right: null };
const dad = { name: 'Dad', left: null, right: null };
const uncle = { name: 'Uncle', left: null, right: null };

grandpa.left = dad;
grandpa.right = uncle;

function postorderTraversal(node) {
    if (node === null) {
        return;
    }
    postorderTraversal(node.left);
    postorderTraversal(node.right);
    console.log(node.name);
}

// Your code here

Hint

Call the function with grandpa to see the postorder output.