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.
题意很清楚，找到二叉树中深度最短的一条路径，DFS（貌似是面试宝典上的一道题）
类似的一道题：http://www.cnblogs.com/double-win/p/3737262.html
/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int minDepth(TreeNode *root) {
if(root==NULL) return ;
if(root->left==NULL && root->right==NULL) return ; int Leftdepth = minDepth(root->left);
int Rightdepth = minDepth(root->right); if(Leftdepth==)
return Rightdepth+;
else if(Rightdepth==)
return Leftdepth+; return min(Leftdepth,Rightdepth)+;
}
};