Sort odd even

You are given an array of integers. Write a script to sort odd index elements in decreasing order and even index elements in increasing order in the given array.

Examples

Example 1
Input: @ints = (4, 1, 2, 3)
Output: (2, 3, 4, 1)
Even index elements: 4, 2 => 2, 4 (increasing order)
Odd index elements : 1, 3 => 3, 1 (decreasing order)

Example 2
Input: @ints = (3, 1)
Output: (3, 1)

Example 3
Input: @ints = (5, 3, 2, 1, 4)
Output: (2, 3, 4, 1, 5)
Even index elements: 5, 2, 4 => 2, 4, 5 
   (increasing order)
Odd index elements : 3, 1 => 3, 1 (decreasing order)

Analysis

As the title suggests, plenty of loops. Why not? Go for it and don't forget to use DIY tool.

This review may cover either or both challenges for this week.

I am sorry that the 'Try it' feature is currently working very slowly or not at all owing to some issue with my web hosting provider.

Try it 

Try running the script with any input:

Your @array =

example: 3, 1, 4, 1, 5, 9, 2, 6, 5, 4

⤡

#!/usr/bin/perl

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

use v5.26;    # The Weekly Challenge - 2025-02-24
use utf8;     # Week 310 - task 2 - Sort odd even
use warnings; # Peter Campbell Smith
binmode STDOUT, ':utf8';

sort_odd_even(4, 1, 2, 3);
sort_odd_even(3, 1);
sort_odd_even(5, 3, 2, 1, 4);
sort_odd_even(3, 7, 9, 3, 2, 6, 8, 1, 0, 4, 2, 5);
sort_odd_even(-3, -2, -1, 0, 1, 2, 3);

sub sort_odd_even {
    
    my (@array, $v, @odds, @evens, @output);
    
    # separate odds and evens
    @array = @_;
    for $v (0 .. $#array) {
        unshift @odds, $array[$v] if $v & 1;
        unshift @evens, $array[$v] unless $v & 1;
    }
    
    # sort them as specified
    @odds = sort {$b <=> $a} @odds;
    @evens = sort {$a <=> $b} @evens;

    # recreate @array in sorted order
    for $v (0 .. $#array) {
        push @output, shift @odds if $v & 1;
        push @output, shift @evens unless $v & 1;
    }
    
    say qq[\nInput:  \@array = (] . join(', ', @array) . ')';
    say qq[Output:        = (] . join(', ', @output) . ')';
}

13 lines of code

Output from script

Input:  @array = (4, 1, 2, 3)
Output:        = (2, 3, 4, 1)

Input:  @array = (3, 1)
Output:        = (3, 1)

Input:  @array = (5, 3, 2, 1, 4)
Output:        = (2, 3, 4, 1, 5)

Input:  @array = (3, 7, 9, 3, 2, 6, 8, 1, 0, 4, 2, 5)
Output:        = (0, 7, 2, 6, 2, 5, 3, 4, 8, 3, 9, 1)

Input:  @array = (-3, -2, -1, 0, 1, 2, 3)
Output:        = (-3, 2, -1, 0, 1, -2, 3)