#!/usr/local/bin/perl
use 5.012;
use List::Util qw/shuffle/;

sub countingsort {
    my @bucket;
    $bucket[$_]++ for @_;
    map { ($_) x $bucket[$_] } 0..@bucket-1;
}

my @random = shuffle 1..42;
say join(",", @random);
say join(",", countingsort @random);
say join(",", sort { $a <=> $b } @random);