LeetCode：111_Minimum Depth of Binary Tree | 二叉树的最小深度 | Easy

 1 struct TreeNode {
 2     int            val;
 3     TreeNode    *left;
 4     TreeNode    *right;
 5     TreeNode(int x): val(x),left(NULL), right(NULL) {}
 6 };
 7 
 8 int minDepth(TreeNode *root) 
 9 {
10     if (NULL == root)
11         return 0;
12     int l = minDepth(root->left);
13     int r = minDepth(root->right);
14     if (!l)
15         return r+1;
16     if (!r)
17         return l+1;
18     return (l<r)?l+1:r+1;
20 }