209. Minimum Size Subarray Sum

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.

 思路：经典的滑动窗口。右指针向右移动，如果和大于sum，记录size，比较是否存入min。然后将左指针右移，继续判断。

public class Solution {
    public int minSubArrayLen(int s, int[] nums) {
    if(nums.length==0)
    {
        return 0;
    }
    int i=0,j=0,sum=0;
    int min=Integer.MAX_VALUE;
    while(j<nums.length)
    {
        sum+=nums[j];
        while(sum>=s)
        {
            min=Math.min(min,j-i+1);
            sum-=nums[i];
            i++;
        }
        j++;
    }
    if(min==Integer.MAX_VALUE)
    {
        return 0;
    }
    return min;
    }
}