209、长度最小的子数组

1、题目描述

题意：找出数组中总和≥target的长度最小的连续子数组的长度。

2、分析

3、实现代码

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <stack>
#include <map>
#include <math.h>
#include <unordered_map>

using namespace std;


class Solution {
public:
    int minSubArrayLen(int target, vector<int>& nums) {
        int min_len = INT32_MAX;
        int beg = 0;//滑动窗口左边界
        int sum = 0;
        for(int i = 0; i < nums.size(); i++){
            sum += nums[i];
            //①累计和sum<target就不断拓宽右边界i
            if(sum < target){
                continue;
            //②一旦累计和sum≥target，就要收缩左边界
            }else{
                //一直收缩到sum不在≥target
                while(beg <= i && sum >= target){
                    min_len = min(min_len, i - beg + 1);
                    sum = sum - nums[beg];
                    beg++;
                }
            }
        }
        //返回最终的结果
        return min_len == INT32_MAX ? 0 : min_len;
    }
};

int main()
{
    Solution s1;
    //int target = 7;
    //vector<int> nums{2,3,1,2,4,3};
    //int target = 4;
    //vector<int> nums{1,4,4};
    int target = 11;
    vector<int> nums{1,1,1,1,1,1,1,1};
    cout << s1.minSubArrayLen(target, nums) << endl;

}