LeetCode--Maximum Depth of Binary Tree

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.

思路：递归。二叉树最大深度经典结论，左右分别递归下去，每层深度加1，求最大值。

/** * 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 maxDepth(TreeNode* root) {        if(!root) return 0;        return max(maxDepth(root->left),maxDepth(root->right))+1;    }};