class Solution {public:    int minSubArrayLen(int s, vector
     
      & nums) {        int w = 0, _sum = 0, res = INT_MAX;        for (int i = 0; i < nums.size(); i++) {            _sum += nums[i];            while (w <= i && _sum >= s) {                res = min(res, i-w+1);                _sum -= nums[w];                w++;            }        }        return res == INT_MAX ? 0 : res;    }};