#!/usr/bin/perl

use strict;
use warnings;
no warnings 'recursion';
use Benchmark qw(timethese);

my @w;
my $max = 5000;

# $w[$_] = int rand(20000) foreach (1..$max);
# @w = 1..$max;
@w = reverse 1..$max;

sub merge {
    my @v = merge_sort (@w);
    # print "@v \n";
}

sub merge_sort {
    my @x = @_;
    return @x if @x < 2;
    my $m = int @x / 2;
    my @a = merge_sort(@x[0 .. $m - 1]);
    my @b = merge_sort(@x[$m .. $#x]);
    for (@x) {
        $_ = !@a ? shift @b
           : !@b ? shift @a
           : $a[0] <= $b[0] ? shift @a 
           :       shift @b;    
    }
    @x;
}


sub quick {
    my @d = quick_sort (@w);
    #print "@d \n"
}

sub quick_sort {
    my @a = @_;
    return @a if @a < 2;
    my $p = pop @a;
    quick_sort(grep $_ < $p, @a), $p, quick_sort(grep $_ >= $p, @a);
} 

timethese (80, {
    'quick' => \&quick,
    'merge' => \&merge,

} );
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