BST Search Operation in DSA Typescript - Build from Scratch

BST Search Operation

📖 Scenario: You are building a simple phone book app that stores contacts in a Binary Search Tree (BST). Each contact has a unique phone number. You want to find if a contact exists by searching the BST.

🎯 Goal: Build a TypeScript program that creates a BST with given phone numbers, then searches for a specific phone number in the BST.

📋 What You'll Learn

Create a BST node class with value, left, and right properties

Insert given phone numbers into the BST in the given order

Create a function to search for a phone number in the BST

Print true if the phone number is found, otherwise false

💡 Why This Matters

🌍 Real World

Binary Search Trees are used in phone books, contact lists, and databases to quickly find information by key.

💼 Career

Understanding BST search is important for software engineers working with data storage, search engines, and performance optimization.

1

Create BST Node Class and Insert Nodes

Create a class called BSTNode with a constructor that takes a value of type number. It should have public properties value, left, and right initialized to null. Then create a variable called root and insert these phone numbers in this order: 50, 30, 70, 20, 40, 60, 80 using a helper function insertNode.

DSA Typescript

// Define BSTNode class
// Create root node with value 50
// Insert other values using insertNode function
// Your code here

Hint

Think of each node as a contact with a phone number. Insert smaller numbers to the left, bigger to the right.

2

Set the Phone Number to Search

Create a variable called searchValue and set it to 40. This is the phone number you want to find in the BST.

DSA Typescript

class BSTNode {
    value: number;
    left: BSTNode | null;
    right: BSTNode | null;

    constructor(value: number) {
        this.value = value;
        this.left = null;
        this.right = null;
    }
}

function insertNode(root: BSTNode | null, value: number): BSTNode {
    if (root === null) {
        return new BSTNode(value);
    }
    if (value < root.value) {
        root.left = insertNode(root.left, value);
    } else {
        root.right = insertNode(root.right, value);
    }
    return root;
}

let root: BSTNode | null = new BSTNode(50);
root = insertNode(root, 30);
root = insertNode(root, 70);
root = insertNode(root, 20);
root = insertNode(root, 40);
root = insertNode(root, 60);
root = insertNode(root, 80);

// Create searchValue variable and set it to 40
// Your code here

Hint

This variable holds the phone number you want to find in the tree.

3

Implement BST Search Function

Create a function called searchBST that takes two parameters: root of type BSTNode | null and value of type number. It should return true if the value is found in the BST, otherwise false. Use the BST property to decide whether to search left or right subtree or return true if found.

DSA Typescript

function searchBST(root: BSTNode | null, value: number): boolean {
        return false;
    if (root.value === value) {
        return true;
        return searchBST(root.left, value);
        return searchBST(root.right, value);
// Print the search result below

Hint

Use recursion to go left if value is smaller, right if bigger, or return true if found.

4

Print Search Result

Use console.log to print the result of calling searchBST with root and searchValue. It should print true if the value is found, otherwise false.

DSA Typescript

Hint

Call searchBST(root, searchValue) and print the result using console.log.