Medium
Quiz
#102 Binary Tree Level Order Traversal
APPROACH
Given the root of a binary tree, collect node values level by level from top to bottom, left to right, and return them as a list of lists.
Example 1:
Input: root = [3,9,20,null,null,15,7]
Output: [[3],[9,20],[15,7]]
Example 2:
Input: root = [1]
Output: [[1]]
Example 3:
Input: root = []
Output: []
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1:00
What is the optimal approach for this problem?