力扣209. 长度最小的子数组

class Solution {
public:
    int minSubArrayLen(int target, vector<int>& nums) {
        int result = nums.size();
        int slow = 0;
        int sign = true;

        for(int fast = 0, sum = 0; fast < nums.size(); fast++) {
            sum += nums[fast];
            while(sum >= target) {
                sign = false;
                result = min(result, fast - slow + 1);
                sum -= nums[slow++];
            }
        }
        if(sign){
            return 0;
        }
        return result;
    }
};