k-radius-subarray-averages_2090.py

# You are given a 0-indexed array nums of n integers, and an integer k.

# The k-radius average for a subarray of nums centered at some index i with
# the radius k is the average of all elements in nums between the indices i - k and i + k (inclusive).
# If there are less than k elements before or after the index i, then the k-radius average is -1.

# Build and return an array avgs of length n where avgs[i] is the k-radius average for the subarray centered at index i.

# The average of x elements is the sum of the x elements divided by x, using integer division.
# The integer division truncates toward zero, which means losing its fractional part.

# For example, the average of four elements 2, 3, 1, and 5 is (2 + 3 + 1 + 5) / 4 = 11 / 4 = 2.75, which truncates to 2.


# Example 1:

# 
# Input: nums = [7,4,3,9,1,8,5,2,6], k = 3
# Output: [-1,-1,-1,5,4,4,-1,-1,-1]
# Explanation:
# - avg[0], avg[1], and avg[2] are -1 because there are less than k elements before each index.
# - The sum of the subarray centered at index 3 with radius 3 is: 7 + 4 + 3 + 9 + 1 + 8 + 5 = 37.
#   Using integer division, avg[3] = 37 / 7 = 5.
# - For the subarray centered at index 4, avg[4] = (4 + 3 + 9 + 1 + 8 + 5 + 2) / 7 = 4.
# - For the subarray centered at index 5, avg[5] = (3 + 9 + 1 + 8 + 5 + 2 + 6) / 7 = 4.
# - avg[6], avg[7], and avg[8] are -1 because there are less than k elements after each index.
# Example 2:

# Input: nums = [100000], k = 0
# Output: [100000]
# Explanation:
# - The sum of the subarray centered at index 0 with radius 0 is: 100000.
#   avg[0] = 100000 / 1 = 100000.
# Example 3:

# Input: nums = [8], k = 100000
# Output: [-1]
# Explanation:
# - avg[0] is -1 because there are less than k elements before and after index 0.

# ---------------------------------------Runtime 1614 ms Beats 82.86% Memory 34.8 MB Beats 58.79%---------------------------------------

# My Solution
# Time Complexity O(n*k)


class Solution:
    def getAverages(self, nums: list[int], k: int) -> list[int]:
        nums_length: int = len(nums)
        ans: list[int] = [-1] * nums_length

        left: int = 0
        cur_window_sum: int = 0
        new_k: int = k * 2 + 1
        for right in range(nums_length):
            cur_window_sum += nums[right]
            if (left + right + 1) >= new_k:
                ans[left + k] = cur_window_sum // new_k
                cur_window_sum -= nums[left]
                left += 1
        return ans