Minimum Depth of Binary Tree

题目：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.

实例代码如下：

class Solution {public:int minDepth(TreeNode *root) {if(root==NULL)return 0;else{int mindepth=INT_MAX;vector<TreeNode*> treeNodeVec;minDepthFunc(root,mindepth,treeNodeVec);return mindepth;}}void minDepthFunc(TreeNode* root,int &mindepth,vector<TreeNode*> &treeNodeVec){if(root!=NULL){//首先访问根节点，加入vectreeNodeVec.push_back(root);//判断是否到达根节点if(root->left==NULL && root->right==NULL){if(treeNodeVec.size()<mindepth)mindepth=treeNodeVec.size();treeNodeVec.pop_back();//叶节点回溯return; //返回到上一层}if(root->left!=NULL)minDepthFunc(root->left,mindepth,treeNodeVec);if(root->right!=NULL)minDepthFunc(root->right,mindepth,treeNodeVec);treeNodeVec.pop_back();//非叶节点回溯}}};