/**
* struct TreeNode {
* int val;
* struct TreeNode *left;
* struct TreeNode *right;
* };
*/
class Solution {
public:
/**
*
* @param root TreeNode类
* @return int整型
*/
int maxDepth(TreeNode* root) {
// write code here
if(root == nullptr){
return 0;
}
int left = maxDepth(root->left);
int right = maxDepth(root->right);
return max(left, right)+1;
}
};