is Balanced Binary Tree

Problem Statement:

Given a binary tree, determine if it is  height-balanced. A height-balanced binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.

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

Solution:

class Solution {
    public boolean isBalanced(TreeNode root) {
        if (root == null) {
            return true;
        }
        
        int leftHeight = height(root.left);
        int rightHeight = height(root.right);
        
        if (Math.abs(leftHeight - rightHeight) > 1) {
            return false;
        }
        
        return isBalanced(root.left) && isBalanced(root.right);
    }
    
    int height(TreeNode root) {
        if (root == null) {
            return 0;
        }
        
        int leftHeight = height(root.left);
        int rightHeight = height(root.right);
        
        return 1 + Math.max(leftHeight, rightHeight);
    }
}