Eric 的小站

1
输入：root = [3,9,20,null,null,15,7]
2
输出：3

1
输入：root = [1,null,2]
2
输出：2

1
/**
2
 * Definition for a binary tree node.
3
 * struct TreeNode {
4
 *     int val;
5
 *     TreeNode *left;
6
 *     TreeNode *right;
7
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
8
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
9
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
10
 * };
11
 */
12
class Solution {
13
public:
14
    int maxDepth(TreeNode* root) {
15
    if (root == nullptr) return 0;
16
       int l_depth = maxDepth(root->left);
17
       int r_depth = maxDepth(root->right);
18
       return max(l_depth,r_depth)+1;
19
    }
20
};