Leetcode172: 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.

class Solution {public:    int minSubArrayLen(int s, vector<int>& nums) {        int n = nums.size();        int i = 0;         int j = 0;        int minlen = n+1;        int sum = 0;        while(i <= j && j < n && sum < s)        {            sum += nums[j];            while(i <= j && sum >= s)            {                minlen = min(minlen, j-i+1);                sum -= nums[i];                i++;            }            j++;        }        return minlen == n+1 ? 0:minlen;    }};