一前一後兩根指標，噹噹前陣列的和大於s時，移動前面的指標直到和小於s為止，比較當前陣列長度與ans的大小。

class Solution:
     # @param nums: a list of integers
     # @param s: an integer
     # @return: an integer representing the minimum size of subarray
    def minimumSize(self, nums, s):
        # write your code here
        i, j= 0, 0
        n = len(nums)
        tmp_sum = 0
 

        ans = n + 1
        while j < n:
            tmp_sum += nums[j]
            if tmp_sum >= s:
                while tmp_sum >= s and j >= i:
                    ans = min(ans, j - i + 1)
                    tmp_sum -= nums[i]
                    i += 1
            j += 1

        return
 
 ans if ans <= n else -1