/**
* 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 false;
int i=getH(root.left);
int j=getH(root.right);
if(i<0||j<0||Math.abs(i-j)>1)
return false;
return true;
}
public int getH(TreeNode root){
if(root==null)
return 0;
int a=getH(root.left);
int b=getH(root.right);
if(Math.abs(a-b)>1||a<0||b<0){
return -1;
}
return a>b?a+1:b+1;
}
}
