Count subarrays with score less than K

class Solution:
    def countSubarrays(self, nums: List[int], k: int) -> int:

        prefix_sum = [0]*len(nums)
        prefix_sum[0] = nums[0]
        for i in range(1, len(nums)):
            prefix_sum[i] = prefix_sum[i-1] + nums[i]

        # we will have a left and right pointer
        left = 0
        current_sum = 0
        ans = 0

        def get_window_sum(left, right):
            if left > right: return 0
            return prefix_sum[right] - prefix_sum[left] + nums[left]

        for right in range(len(nums)):

            # first calculate the window sum
            window_sum = get_window_sum(left, right)

            # keep reducing the window untill the window_sum*
            while (right >= left and window_sum*(right-left+1)>=k):
                left += 1
                window_sum = get_window_sum(left, right)

            ans += right - left + 1

class Solution:
    def countSubarrays(self, nums: List[int], k: int) -> int:

        # we will have a left and right pointer
        left = 0
        current_sum = 0
        ans = 0

        for right in range(len(nums)):
            current_sum += nums[right]

            # keep reducing the window untill the window_sum*
            while (current_sum*(right - left + 1) >=k):
                current_sum -= nums[left]
                left += 1

            ans += right - left + 1

        return ans