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Grokking the Coding Interview Patterns in JavaScript

Binary Tree Level Order Traversal

Explore how to implement a binary tree level order traversal using breadth-first search. Understand the process of traversing tree nodes level by level and returning their values efficiently in JavaScript.

We'll cover the following...

Statement

Given the root of a binary tree, display the values of its nodes while performing a level order traversal. Return the node values for all levels in a string separated by the character :. If the tree is empty, i.e., the number of nodes is 00, then return “None” as the output.

Constraints:

  • The number of nodes in the tree is in the range [0,500][0, 500].

  • −103≤-10^3 \leq Node.data ≤103\leq 10^3

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Technical Quiz
1.

How does BFS ensure that it visits all nodes in a binary tree while traversing level by level?

A.

By using a stack data structure to keep track of visited nodes

B.

By using a queue data structure to maintain the order of node exploration

C.

By recursively traversing the left and right subtrees in a depth-first manner

D.

By randomizing the order of node exploration for better coverage

1 / 3

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3
4
5

Try it yourself

Implement your solution in main.js in the following coding playground. You’ll need the provided supporting code to implement your solution.

Note: The binary tree node’s class has members left and right to store references to other nodes, along with the member data to hold the node’s value.

JavaScript
usercode > main.js
// Definition of a binary tree node

// class TreeNode {

//   constructor(data) {

//     this.data = data;

//     this.left = null;

//     this.right = null;

//   }

// }



import {TreeNode} from './ds_v1/BinaryTree.js';

import Queue from "./queue.js";





export let  levelOrderTraversal = function(root) {



    // Replace this placeholder return statement with your code

    return ""

}
Binary Tree Level Order Traversal