【Leetcode长征系列】Minimum Depth of Binary Tree

原题：

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.

思路：
递归实现深度优先，开辟全局变量记录最小depth值！

代码如下：

/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
int min = INT_MAX;
public:
int minDepth(TreeNode *root) {
int depth = 0;
if(root==NULL) return 0;

dfs(root,depth);
return min;
}

int dfs(TreeNode *root, int depth){
if(root==NULL) return 0;

depth++;
if(root->left==NULL && root->right==NULL) return min = depth>min?min:depth;

dfs(root->left, depth);
dfs(root->right,depth);
}
};

这么多天…终于遇到一道简单点的题了……………