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.

Solution:

/**
 * 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) {
        return isBalancedInt(root)>=0;
    }
    
    private int isBalancedInt(TreeNode root)
    {
        if (root==null)
            return 0;
        if (root.left==null && root.right==null)
            return 1;
        int left = isBalancedInt(root.left);
        int right = isBalancedInt(root.right);
        if (left ==-1 || right==-1 || Math.abs(left-right)>1)
            return -1;
        return Math.max(left, right)+1;
        
    }
}