Java for LeetCode 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.

解题思路：

用一个指针维护左边界即可，JAVA实现如下：

    public int minSubArrayLen(int s, int[] nums) {
    	if(nums==null||nums.length==0)
    		return 0;
    	int left=0,sum=0,min=Integer.MAX_VALUE;
    	for(int i=0;i<nums.length;i++){
    		sum+=nums[i];
    		while(sum>=s){
    			min=Math.min(min, i-left+1);
    			sum-=nums[left++];
    		}
    	}
    	return min==Integer.MAX_VALUE?0:min;
    }