/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    boolean result=true;
    int calHeight(TreeNode root)
    {
        if(!result)
        {
            return 0;
        }
        int left=1;
        int right=1;
        if(root.left!=null)
        {
            left+=calHeight(root.left);
        }
        if(root.right!=null)
        {
            right+=calHeight(root.right);
        }
        if(left>right+1||right>left+1)
        {
            result=false;
        }
        return Math.max(left,right);
    }
    public boolean isBalanced(TreeNode root) {
        if(root==null)
        {
            return true;
        }
        calHeight(root);
        return result;
    }
}