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# minimum-size-subarray-sum-209

发表于 2016-10-11 更新于 2020-01-12 分类于 leetcode 阅读次数： 阅读次数： Disqus：

### problem

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.

#### 题解

参考，滑动窗口，跟之前Data Structure课上的online算法有点像，链接

#### Code

    class Solution {
    public:
        int minSubArrayLen(int s, vector<int>& nums) {
            int len = nums.size();
            if(len == 0) return 0;
            int minlen = INT_MAX;
            int sum = 0;

            int left = 0;
            int right = -1;
            while(right < len)
            {
                while(sum < s && right < len)
                    sum += nums[++right];
                if(sum >= s)
                {
                    minlen = minlen < right - left + 1 ? minlen : right - left + 1;
                    sum -= nums[left++];
                }
            }
            return minlen > len ? 0 : minlen;
        }
    };