number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold_1343.py

# Given an array of integers arr and two integers k and threshold, return the
# number of sub-arrays of size k and average greater than or equal
# to threshold.

# Example 1:

# Input: arr = [2,2,2,2,5,5,5,8], k = 3, threshold = 4
# Output: 3
# Explanation: Sub-arrays [2,5,5],[5,5,5] and [5,5,8] have averages 4, 5 and 6
# respectively. All other sub-arrays of size 3 have averages
# less than 4 (the threshold).
# Example 2:

# Input: arr = [11,13,17,23,29,31,7,5,2,3], k = 3, threshold = 5
# Output: 6
# Explanation: The first 6 sub-arrays of size 3 have averages greater than 5. Note that averages are not integers.

# ---------------------------------------Runtime 586 ms Beats 94.74% Memory 29.4 MB Beats 76.36%---------------------------------------
# My Solution
# Time Complexity O(n)


class Solution:
    def numOfSubarrays(self, arr: list[int], k: int, threshold: int) -> int:
        cur_window: int = sum(arr[:k])
        ans: int = 0
        if cur_window // k >= threshold:
            ans += 1
        for i in range(len(arr) - k):
            cur_window = cur_window - arr[i] + arr[i + k]
            if cur_window // k >= threshold:
                ans += 1
        return ans