Balanced Binary Tree

/*
判断一颗二叉树是否是平衡二叉树（左右子节点的高度差不超过1或者是颗空树）
*/
/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxDepth(struct TreeNode *root) {
        if(!root) return 0;
        if(!root->left && !root->right) return 1;
        return max(maxDepth(root->left),maxDepth(root->right))+1;
    }
    bool isBalanced(TreeNode *root) {
        if(!root) return true;
        int left = maxDepth(root->left);
        int right = maxDepth(root->right);
        return (abs(left-right)<=1)&&isBalanced(root->left)&&isBalanced(root->right);
    }
};