#245 Level Order Traversal of Binary Tree

medium

javascript

blind75

binary-tree

bfs

Given a binary tree root, return its level order traversal as a nested array, where each subarray contains the values of nodes at a particular level in the tree, from left to right.

Constraints:

0 ≤ Number of nodes in the tree ≤ 1000
-1000 ≤ Node values ≤ 1000

Examples:

// Example 1:

//        1

//      /   \

//     2     3

//    / \   / \

//   4   5 6   7

const root1 = createTree([1, 2, 3, 4, 5, 6, 7]);
console.log(levelOrder(root1));
// Output: [[1], [2, 3], [4, 5, 6, 7]]


// Example 2:

//   1

const root2 = createTree([1]);
console.log(levelOrder(root2));
// Output: [[1]]


// Example 3:

const root3 = createTree([]);
console.log(levelOrder(root3));
// Output: []


// Example 4:

//        1

//      /   \

//     2     3

//      \     \

//       4     5

const root4 = createTree([1, 2, 3, null, 4, null, 5]);
console.log(levelOrder(root4));
// Output: [[1], [2, 3], [4, 5]]