Likou selected top interview questions---------the maximum depth of the binary tree

Topic link

Idea: This
question is very simple, just dfs.

Code:

在这里插入代码片/**
 * 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==NULL) return 0;
        int left = maxDepth(root->left) ;
        int right = maxDepth(root->right) ;
        return max(left,right)+1;
    }
};