left and right to 0, which will represent the bounds of the sliding window.windowSum to 0, which will keep track of the sum of elements within the window.valid to 0, which will count the number of valid subarrays.right pointer over the array, adding the current element to windowSum.windowSum * (right - left + 1)) is greater than or equal to k, shrink the window from the left by subtracting the left element from windowSum and incrementing left.right, add the number of valid subarrays ending at right to valid, which is right - left.right has reached the end of the array.valid.