[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 0;
        queue<TreeNode* > qu;
        TreeNode * curNode;
        qu.push(root);
        int ret =0;
        while(!qu.empty()){
            ret ++;
            int n = qu.size();
            while(n-->0){
                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 0;
}