Leetcode | 104. 二叉树的最大深度

 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     {
14         if(!root)
15             return 0;
16         int count = 0;
17         int nums = 0;
18         dfs(root, count, nums);
19         return nums;              
20     }
21     
22     void dfs(TreeNode *root, int count, int &nums)
23     {
24         ++count;
25         if(count > nums)
26             nums = count;
27         if(!root->left && !root->right)
28             return;
29         if(root->left)
30             dfs(root->left, count, nums);
31         if(root->right)
32             dfs(root->right, count, nums);          
33     }
34 };

 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) return 0;
14         return 1 + max(maxDepth(root->left), maxDepth(root->right));
15     }
16 };