Binary Tree Level Order Traversal

Oracle Interview Question

Problem Overview

Difficulty: Medium
LeetCode Pattern: BFS

Given the root of a binary tree, return the level order traversal of its nodes’ values. (i.e., from left to right, level by level).

Input:
  3
 / \
9   20
   /  \
  15   7

Output:
· [[3],[9,20],[15,7]]