Balanced Binary Tree

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

Output: true

The left subtree has height 1 (just node 9), and the right subtree has height 2 (node 20 with children 15, 7). At every node, the height difference between subtrees is at most 1.

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

Output: false

The left subtree of the root has height 3, while the right subtree has height 1. The difference is 2, which exceeds the allowed difference of 1.

Input: root = []

Output: true

An empty tree is considered balanced by definition.

Balanced Binary Tree

Problem

Constraints

Examples