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 a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public boolean isBalanced(TreeNode root) {
        if(root == null) return true;
        if(deep(0,root) == -99) return false;
        return true;
    }
    public int deep(int deep, TreeNode root){
        if(root == null){
            return deep-1;
        }
        int l = deep(deep+1,root.left);
        int r = deep(deep+1,root.right);
        if(Math.abs(l-r) >1){
            return -99;
        }
        return l>r?l:r;
    }
}