LeetCode Minimum Size Subarray Sum

Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead.

For example, given the array [2,3,1,2,4,3] and s = 7,
the subarray [4,3] has the minimal length under the problem constraint.

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More practice:

If you have figured out the O(n) solution, try coding another solution of which the time complexity is O(n log n).

Credits:
Special thanks to @Freezen for adding this problem and creating all test cases.

典型two-pointer题：

class Solution {

public:

    int minSubArrayLen(int s, vector<int>& nums) {

        int minlen = INT_MAX;

        int len = nums.size();

        

        int p = 0;

        int q = 0;

        int csum = 0;

        while (q < len) {

            csum += nums[q];

            while (csum >= s) {

                minlen = min(minlen, q - p + 1);

                csum -=nums[p++];

            }

            q++;

        }

        return minlen == INT_MAX ? 0 : minlen;

    }

};