[LeetCode] Minimum Depth of Binary Tree 二叉树最小深度

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.

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    这题是找二叉树的最小深度，这是广度搜索比较好吧，为啥提示给的是 深度优先呢。

1. 判断树是否为空
2. 将root 节点压入队列
3. while 队列不为空
4. 计算当前队列的个数，进行这么多次的第5步
5. 获取queue 头，弹出一个，判断弹出的时候为叶子，是的返回，不是将支点加入队列

 #include <iostream>
 #include <queue>
 using namespace std;
 /**
  * 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 ;
         queue<TreeNode* > qu;
         TreeNode * curNode;
         qu.push(root);
         int ret =;
         while(!qu.empty()){
             ret ++;
             int n = qu.size();
             while(n-->){
                 curNode =qu.front();
                 qu.pop();
                 if(curNode->left==NULL&&curNode->right==NULL)   return ret;
                 if(curNode->left!=NULL) qu.push(curNode->left);
                 if(curNode->right!=NULL)    qu.push(curNode->right);
             }
         }
         return ret;
     }
 };

 int main()
 {

     Solution sol;
     return ;
 }