leetcode--Balanced Binary Tree

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 depth of the two subtrees of every node never differ by more than 1.

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean isBalanced(TreeNode root){
       boolean isBalanced = true;
        if(root != null){
            if(heightOfTree(root.left) > heightOfTree(root.right) + 1 || 
                 heightOfTree(root.left) < heightOfTree(root.right) - 1)
                 isBalanced = false;
            else
                 isBalanced = isBalanced(root.left) && isBalanced(root.right);
        }
        return isBalanced;
    }
    
    public int heightOfTree(TreeNode root){
        int height = 0;
        if(root != null)
            height = 1 + Math.max(heightOfTree(root.left), heightOfTree(root.right));
        return height;
    }    
}