leetcode 104

104. 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.

求二叉树的最大深度。

采用递归实现：

（1）如果二叉树为空，二叉树的深度为0
（2）如果二叉树不为空，二叉树的深度 = max(左子树深度，右子树深度) + 1

代码如下：

 1 /**
 2  * Definition for a binary tree node.
 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)
14         {
15             return 0;
16         }
17         int left = maxDepth(root->left);
18         int right = maxDepth(root->right);
19         
20         return left > right ? (left + 1) : (right + 1);
21     }
22 };