クイックソートその2

quicqsort2.pl

#!/usr/bin/env perl

use strict;
use warnings;
use feature 'say';

use DDP { deparse => 1 };

my @seeds;
for (1..10){
    push(@seeds, int(rand(100)));
}
p @seeds;
quick_sort(\@seeds, 0, ((scalar @seeds) - 1));
p @seeds;

sub quick_sort{
    my $array = shift;
    my $head = shift;
    my $tail = shift;
    my $l = $head;
    my $r = $tail;
    my $center_val = $array->[$l];
    my $now_val = $array->[$r];

    if ($l >= $r){
        return;
    } else {

        while ($l != $r){
            if ($now_val > $center_val){
                $array->[$r] = $now_val;
                $r--;
                $now_val = $array->[$r];
            } else {
                $array->[$l] = $now_val;
                $l++;
                $now_val = $array->[$l];
            }
        }
        $array->[$l] = $center_val;
        quick_sort($array, $head, $l -1);
        quick_sort($array, $l + 1, $tail);
    }
}