209. 长度最小的子数组

输入: s = 7, nums = [2,3,1,2,4,3]
输出: 2
解释: 子数组 [4,3] 是该条件下的长度最小的子数组。

   public int minSubArrayLen(int s, int[] nums) {
        if(nums.length==0){
            return 0;
        }
        int rtn = 0;
        int target = nums[0];
        int left = 0;
        int right = 0;
        while (left < nums.length) {
            if (target >= s) {
                if (rtn == 0) {
                    rtn = right - left + 1;
                } else {
                    rtn = Math.min(rtn, right - left + 1);
                }
                left = left + 1;
                target = target - nums[left - 1];
            } else {
                right = right + 1;
                if (right < nums.length) {
                    target = target + nums[right];
                } else {
                    break;
                }
            }
        }
        return rtn;
    }