Table of Contents

## Question

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as:

a binary tree in which the left and right subtrees of

everynode differ in height by no more than 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

**Example 3:**

Input:root = []Output:true

**Constraints:**

- The number of nodes in the tree is in the range
`[0, 5000]`

. `-10`

^{4}<= Node.val <= 10^{4}

## Python Solution

# Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right def height(root): global isBal if not root: return 0 lh = height(root.left) rh = height(root.right) if abs(lh-rh)>1:isBal= False return 1+max(lh,rh) class Solution: def isBalanced(self, root: TreeNode) -> bool: global isBal isBal = True height(root) return isBal