**

* Definition for a binary tree node.

* public class TreeNode {

* int val;

* TreeNode left;

* TreeNode right;

* TreeNode() {}

* TreeNode(int val) { this.val = val; }

* TreeNode(int val, TreeNode left, TreeNode right) {

* this.val = val;

* this.left = left;

* this.right = right;

* }

* }

*/

class Solution {

public boolean isBalanced(TreeNode root) {

if(root == null){

return true;

}

int leftHeight = getHeight(root.left);

int rightHeight = getHeight(root.right);

int diff = Math.abs(leftHeight - rightHeight);

if(diff<=1 && isBalanced(root.left) && isBalanced(root.right)){

return true;

}

return false;

}

private int getHeight(TreeNode root){

if(root == null){

return 0;

}

int lh = getHeight(root.left);

int rh = getHeight(root.right);

return Math.max(lh, rh) + 1;

}

}