1619. Mean of Array After Removing Some Elements

Problem

Given an integer array arr, return the mean of the remaining integers after removing the smallest 5% and the largest 5% of the elements.

Answers within 10-5 of the actual answer will be considered accepted.

  Example 1:

Input: arr = [1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3]
Output: 2.00000
Explanation: After erasing the minimum and the maximum values of this array, all elements are equal to 2, so the mean is 2.

Example 2:

Input: arr = [6,2,7,5,1,2,0,3,10,2,5,0,5,5,0,8,7,6,8,0]
Output: 4.00000

Example 3:

Input: arr = [6,0,7,0,7,5,7,8,3,4,0,7,8,1,6,8,1,1,2,4,8,1,9,5,4,3,8,5,10,8,6,6,1,0,6,10,8,2,3,4]
Output: 4.77778

  Constraints:

• 20 <= arr.length <= 1000

• arr.length** **is a multiple of 20.

• 0 <= arr[i] <= 10^5

Solution (Java)

class Solution {
    public double trimMean(int[] arr) {
        Arrays.sort(arr);
        int n = arr.length;
        long sum = 0;
        for (int i = (int) Math.round(n * 0.05); i < (n - n * 0.05); i++) {
            sum += arr[i];
        }
        return sum / (n - n * 0.1);
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).