[LeetCode] MaximumDepth 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.

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