209. ! Minimum Size Subarray Sum

class Solution(object):
    def minSubArrayLen(self, s, nums):
        """
        :type s: int
        :type nums: List[int]
        :rtype: int
        """
        # nums.sort(reverse=True)
        # print(nums)
        # sum = 0
        # for i in range(len(nums)):
        #     sum += nums[i]
        #     if sum >= s:
        #         return i+1
        # return 0
        
        # the subarray should be contiguous!!
        
        # res = 999999
        # for i in range(len(nums)):
        #     j = i
        #     currS = 0
        #     while j < len(nums):
        #         currS += nums[j]
        #         j += 1
        #         if currS >= s:
        #             if j-i < res:
        #                 res = j-i
        #             break
        # if res == 999999:
        #     return 0
        # else:
        #     return res
        
        # overtime
        
        # use 2 points
        
        a, b, currS, res = 0, 0, 0, len(nums)+1
        while b < len(nums):
            while currS < s and b < len(nums):
                currS += nums[b]
                b += 1
            while currS >= s and a < b:
                res = min(res, b-a)
                currS -= nums[a]
                a += 1
        if res == len(nums)+1:
            return 0
        else:
            return res