class Solution {
public:
    int minSubArrayLen(int s, vector<int>& nums) {
        int length = nums.size();
        if (length == 0) {
            return 0;
        }
        
        int left = 0;
        int right = 1;
        int ret = std::numeric_limits<int>::max();
        int sum = nums[0];

        while (right <= length and left < length) {
            if (sum < s) {
                if (right == length) {
                    break;
                }
                else {
                    sum += nums[right];
                    right += 1;
                }
            }
            else {
                ret = min(ret, right-left);
                sum -= nums[left];
                left += 1;
            }
        }
        
        if (ret == std::numeric_limits<int>::max()) {
            return 0;
        }
        else {
            return ret;
        }
    }
};

standard solution

int minSubArrayLen(int s, vector<int>& nums)
{
    int n = nums.size();
    int ans = INT_MAX;
    int left = 0;
    int sum = 0;
    for (int i = 0; i < n; i++) {
        sum += nums[i];
        while (sum >= s) {
            ans = min(ans, i + 1 - left);
            sum -= nums[left++];
        }
    }
    return (ans != INT_MAX) ? ans : 0;

Cautious

• Use ternary operator