Serialize and Deserialize Binary Tree in DSA Javascript - Build from Scratch

Serialize and Deserialize Binary Tree

📖 Scenario: Imagine you are working on a messaging app that needs to send a family tree structure over the internet. To do this, you need to convert the tree into a string format to send it, and then convert it back to the tree structure on the other side.

🎯 Goal: You will build two functions: one to convert a binary tree into a string (serialize), and another to convert that string back into the original binary tree (deserialize).

📋 What You'll Learn

Create a binary tree node class called TreeNode with val, left, and right properties.

Write a function called serialize that converts a binary tree into a string using preorder traversal.

Write a function called deserialize that converts the string back into the original binary tree.

Use null to represent empty nodes in the serialized string.

Print the serialized string and verify the deserialized tree structure.

💡 Why This Matters

🌍 Real World

Serialization and deserialization are used to save and transfer complex data structures like trees in databases, files, or over networks.

💼 Career

Understanding how to serialize and deserialize data structures is important for backend development, data engineering, and working with APIs or distributed systems.

1

Create the Binary Tree Node Class

Create a class called TreeNode with a constructor that takes a parameter val and sets this.val to val, this.left to null, and this.right to null.

DSA Javascript

// Your code here

Hint

Think of each node as a person in the family tree with a value and links to left and right children.

2

Create a Sample Binary Tree

Create a binary tree by creating a root node called root with value 1. Then set root.left to a new TreeNode with value 2, and root.right to a new TreeNode with value 3. Finally, set root.right.left to a new TreeNode with value 4 and root.right.right to a new TreeNode with value 5.

DSA Javascript

class TreeNode {
    constructor(val) {
        this.val = val;
        this.left = null;
        this.right = null;
    }
}

// Your code here

Hint

Build the tree step by step by linking nodes as left and right children.

3

Write the Serialize and Deserialize Functions

Write a function called serialize that takes a root node and returns a string representing the tree using preorder traversal. Use null for empty nodes. Then write a function called deserialize that takes the string and reconstructs the original tree. Use a helper array to process nodes in order.

DSA Javascript

class TreeNode {
    constructor(val) {
        this.val = val;
        this.left = null;
        this.right = null;
    }
}

const root = new TreeNode(1);
root.left = new TreeNode(2);
root.right = new TreeNode(3);
root.right.left = new TreeNode(4);
root.right.right = new TreeNode(5);

// Write serialize and deserialize functions below
// Your code here

Hint

Use preorder traversal: visit node, then left, then right. Use recursion for both serialize and deserialize.

4

Print the Serialized String and Verify Deserialization

Print the serialized string of the root tree by calling serialize(root). Then deserialize the string back to a tree using deserialize. Finally, print the value of the root node of the deserialized tree.

DSA Javascript

class TreeNode {
    constructor(val) {
        this.val = val;
        this.left = null;
        this.right = null;
    }
}

const root = new TreeNode(1);
root.left = new TreeNode(2);
root.right = new TreeNode(3);
root.right.left = new TreeNode(4);
root.right.right = new TreeNode(5);

function serialize(root) {
    const result = [];
    function helper(node) {
        if (node === null) {
            result.push('null');
            return;
        }
        result.push(String(node.val));
        helper(node.left);
        helper(node.right);
    }
    helper(root);
    return result.join(',');
}

function deserialize(data) {
    const nodes = data.split(',');
    function helper() {
        if (nodes.length === 0) return null;
        const val = nodes.shift();
        if (val === 'null') return null;
        const node = new TreeNode(Number(val));
        node.left = helper();
        node.right = helper();
        return node;
    }
    return helper();
}

// Print serialized string and root value of deserialized tree
// Your code here

Hint

The serialized string should show the preorder traversal with 'null' for empty nodes. The deserialized root value should be 1.