【LeetCode】Minimum Size Subarray Sum

Minimum Size Subarray Sum 
Total Accepted: 5312 Total Submissions: 22940 My Submissions Question Solution 
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.
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Credits:
Special thanks to @Freezen for adding this problem and creating all test cases.

【解题思路】

最小滑动窗口。

设定两个指针，每次sum+nums[right]，如果sum >= s就记录下长度。然后重新计算下一轮。
前提是，left需要右移，一直到sum < s为止，再计算下一个sum。

Java AC

public class Solution {    public int minSubArrayLen(int s, int[] nums) {        if (nums == null || nums.length == 0) {            return 0;        }        int len = nums.length;        int sum = 0;        int minLen = len + 1;        int left = 0;        int right = 0;        while (right < len) {            sum += nums[right];            while (sum >= s) {                int curLen = right - left + 1;                minLen = minLen > curLen ? curLen : minLen;                sum -= nums[left];                left++;            }            right++;        }        return minLen == len + 1 ? 0 : minLen;    }}