Binary Tree Level Order Traversal Visualizer & Step-by-Step Algorithm Solution

Traverse binary tree nodes level-by-level from left to right using a FIFO queue (BFS).

Category: trees | Difficulty: Medium

Tags: BFS, Binary Tree, Queue, Level Order

Binary Tree Level Order Traversal

3
9
20
15
7
BFS QUEUE
FRONT
Node(3)
100%
state
result[]
Initialization
1/22
Explanation

Initialize BFS Queue with root Node(3).

Source Code
1function levelOrder(root) {
2 if (!root) return [];
3 const queue = [root];
4 const result = [];
5 while (queue.length > 0) {
6 const levelSize = queue.length;
7 const currentLevel = [];
8 for (let i = 0; i < levelSize; i++) {
9 const node = queue.shift();
10 currentLevel.push(node.val);
11 if (node.left) queue.push(node.left);
12 if (node.right) queue.push(node.right);
13 }
14 result.push(currentLevel);
15 }
16 return result;
17}