Perl uniq array

gistfile1.txt

#!perl

use Benchmark qw/cmpthese/;
use strict;

my @array = ( 'a', 'a', 'a', 'b', 'c', 'd', 'e', 'g', 'e', 'e', 'g', 'c' );

sub uniq_v1 {
    my %tmp;
    my @new_array = grep {
        my $ret = 1;
        if ( exists $tmp{$_} ) {
            $ret = 0;
        }
        $tmp{$_} = 1;
        $ret;
    } @array;
    return @new_array;
}

sub uniq_v1_1 {
    my %tmp = map { $_ => 1; } @array;
    return keys(%tmp);
}

sub good_uniq {
    my %tmp;
    @tmp{@array} = @array;
    return keys(%tmp);
}

sub good_uniq_1 {
    my %tmp;
    @tmp{@array} = 1 x @array;
    return keys(%tmp);
}

use Data::Dumper;

warn Dumper( [ uniq_v1() ], [ uniq_v1_1() ], [ good_uniq() ], [good_uniq_1] );

cmpthese(
    1000000,
    {   'uniq_v1'     => \&uniq_v1,
        'uniq_v1_1'   => \&uniq_v1_1,
        'good_uniq'   => \&good_uniq,
        'good_uniq_1' => \&good_uniq_1
    }
);

__DATA__
                Rate     uniq_v1   uniq_v1_1   good_uniq good_uniq_1
uniq_v1     189036/s          --        -24%        -49%        -73%
uniq_v1_1   250000/s         32%          --        -33%        -64%
good_uniq   373134/s         97%         49%          --        -46%
good_uniq_1 694444/s        267%        178%         86%          --