leetcode209 Minimum Size Subarray Sum

 """
 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.
 Example:
 Input: s = 7, nums = [2,3,1,2,4,3]
 Output: 2
 Explanation: the subarray [4,3] has the minimal length under the problem constraint.
 """
 """
 滑动窗口，与leetcode713类似
 """
 class Solution:
     def minSubArrayLen(self, s: int, nums):
         _sum = 0
         res = len(nums) + 1
         i = 0
         for j in range(len(nums)):
             _sum += nums[j]
             while _sum >= s: #！！！
                 res = min(res, j-i+1)
                 _sum -= nums[i]
                 i += 1
         return res if res <= len(nums) else 0