LeetCode:Minumum Depth of Binary Tree

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

 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 minDepth(TreeNode* root) {
13     //深搜递归
14     
15         if(root==NULL) return 0;
16         if(!root->left&&!root->right)
17             return 1;
18         int leftdepth=minDepth(root->left);
19         int rightdepth=minDepth(root->right);
20         if(leftdepth==0)
21             return rightdepth+1;
22         else if(rightdepth==0)
23             return leftdepth+1;
24         else
25             return min(leftdepth,rightdepth)+1;
26     }
27 };