LeetCode. 209. 长度最小的子数组

输入：s = 7, nums = [2,3,1,2,4,3]
输出：2
解释：子数组 [4,3] 是该条件下的长度最小的子数组。

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

class Solution {
public:
    int minSubArrayLen(int s, vector<int>& nums) {
        int l = 0, r = -1; // nums[l...r]为我们的滑动窗口
        int sum = 0;
        int res = nums.size() + 1;

        while ( l < nums.size()) {
            if ( r + 1 < nums.size() && sum < s) {
                r ++;
                sum += nums[r];
            } else {
                sum -= nums[l++];
            }

            if (sum >= s){
                res = min(res, r-l+1);
            }  
        }
        if (res == nums.size() + 1) {
            return 0;
        }
        return res;
    }
};