209. Minimum Size Subarray Sum

题目

Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous 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.

思路分析

这里要寻找数组中连续数字之和大于等于给定数字的最小子串序列。
滑动窗口的思想，快慢指针
对于最长子串、最短子串的问题发现是一个套路，有代码模板，下一篇博客整理一下。

代码

public int minSubArrayLen(int s, int[] nums) {        int minLen = Integer.MAX_VALUE;        int start = 0,end =0,sum=0;        while(start<nums.length)        {            sum+=nums[end++];            while(sum>=s)            {                minLen = Math.min(minLen, end-start);                sum-=nums[start++];            }        }        return minLen == Integer.MAX_VALUE?0:minLen;    }