Balanced Binary Tree

Easy

Given a binary tree, determine if it is height-balanced — for every node, the heights of its two subtrees differ by at most 1.

Example 1

Input:  root = [3,9,20,null,null,15,7]
Output: true

Example 2

Input:  root = [1,2,2,3,3,null,null,4,4]
Output: false

Constraints

• 0 <= number of nodes <= 5000
• -10^4 <= Node.val <= 10^4