/** * 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) { return getDepth(root) != -1; } public int getDepth(TreeNode root) { if (root == null) { return 0; } int leftDepth = getDepth(root.left); if (leftDepth == -1) { return -1; } int rightDepth = getDepth(root.right); if (rightDepth == -1 || Math.abs(leftDepth - rightDepth) > 1) { return -1; } return 1 + Math.max(leftDepth, rightDepth); } }