DSA Practice
Description
Binary Tree Level Order Traversal
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). Example: Input: `root = [3,9,20,null,null,15,7]` Output: `[[3],[9,20],[15,7]]`
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Requirements
Use a Queue for Breadth-First Search (BFS).
Time complexity: O(N).
Output should be an array of arrays.
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Test Execution
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