Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

大致题意

判断一棵树是不是平衡树

题解

题目类型：dfs

基本的dfs题目，遍历节点的同时计算左右子树的高度，借由此来判断是否时平衡树

代码如下

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int depth (TreeNode *root) {
        if (root == NULL) return 0;
        return max (depth(root -> left), depth (root -> right)) + 1;
    }

    bool isBalanced (TreeNode *root) {
        if (root == NULL) return true;
        
        int left=depth(root->left);
        int right=depth(root->right);
        
        return abs(left - right) <= 1 && isBalanced(root->left) && isBalanced(root->right);
    }
};