2090 - K Radius Subarray Averages.

Medium

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:

• avg0, avg1, and avg2 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 , avg3 = 37 / 7 = 5.

• For the subarray centered at index 4, avg4 = (4 + 3 + 9 + 1 + 8 + 5 + 2) / 7 = 4.

• For the subarray centered at index 5, avg5 = (3 + 9 + 1 + 8 + 5 + 2 + 6) / 7 = 4.

• avg6, avg7, and avg8 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.

avg0 = 100000 / 1 = 100000.

Example 3:

Input: nums = 8, k = 100000

Output: -1

Explanation:

• avg0 is -1 because there are less than k elements before and after index 0.

Constraints:

• n == nums.length

• <code>1 <= n <= 10⁵</code>

• <code>0 <= numsi, k <= 10⁵</code>