Task — Special average

You are given an array of integers. Write a script to return the average excluding the minimum and maximum of the given array.

Examples

Example 1
Input: @ints = (8000, 5000, 6000, 2000, 3000, 7000)
Output: 5250
Min: 2000
Max: 8000
Avg: (3000+5000+6000+7000)/4 = 21000/4 = 5250

Example 2
Input: @ints = (100_000, 80_000, 110_000, 90_000)
Output: 95_000
Min: 80_000
Max: 110_000
Avg: (100_000 + 90_000)/2 = 190_000/2 = 95_000

Example 3
Input: @ints = (2500, 2500, 2500, 2500)
Output: 0
Min: 2500
Max: 2500
Avg: 0

Example 4
Input: @ints = (2000)
Output: 0
Min: 2000
Max: 2000
Avg: 0

Example 5
Input: @ints = (1000, 2000, 3000, 4000, 5000, 6000)
Output: 3500
Min: 1000
Max: 6000
Avg: (2000 + 3000 + 4000 + 5000)/4 = 14000/4 = 3500

Analysis

On the KISS principle (Keep It Simple, Stupid) I sorted the array, summed from the 2nd to the 2nd last elements and divided by the length of the array minus 2.

That's nice readable code, but is it efficient? I tried it with a million random integers in the range 0 - 999,999 and it came up with 499595.1 in under 2 seconds - and about half of that was used to generate the random numbers. So I think that's fast enough.

I take slight issue with example 4 which regards the average of an empty set of numbers as being 0; for the task as stated I treat the input as invalid unless there are at least 3 elements in the array. In real life one would ask the client what they want to happen if there were fewer than 3.

Try it 

#!/usr/bin/perl

# Blog: http://ccgi.campbellsmiths.force9.co.uk/challenge

use v5.26;    # The Weekly Challenge - 2025-12-08
use utf8;     # Week 351 - task 1 - Special average
use warnings; # Peter Campbell Smith
binmode STDOUT, ':utf8';
use Encode;

special_average(8000, 5000, 6000, 2000, 3000, 7000);
special_average(100_000, 80_000, 110_000, 90_000);
special_average(2500, 2500, 2500, 2500);
special_average(1, 3);

sub special_average {
    
    my (@sorted, $sum);
    
    # initialise
    say qq[\nInput:  (] . join(', ', @_) . ')';
    
    # need at lleast 3 elements
    if (@_ > 2) {
        
        # calculate average
        @sorted = sort {$a <=> $b} @_;
        $sum += $sorted[$_] for 1 .. @sorted - 2;
        say qq[Output: ] . ($sum / (@sorted - 2));
    
    # error
    } else {
        say qq[Output: need at least 3 elements];
    }
}

Output

Input:  (8000, 5000, 6000, 2000, 3000, 7000)
Output: 5250

Input:  (100000, 80000, 110000, 90000)
Output: 95000

Input:  (2500, 2500, 2500, 2500)
Output: 2500

Input:  (1, 3)
Output: need at least 3 elements