#!/usr/bin/perl

use strict;
use warnings;

my @array = qw /TATG GTTC GAAC AATA/;
        
# DNA's tend to be loooooooooooooooong, so we create a lookup
# table to calculate the reversed inverse.
my %table;
my @chars = qw /A C G T/;
foreach my $c1 (@chars) {
    foreach my $c2 (@chars) {
        foreach my $c3 (@chars) {
            foreach my $c4 (@chars) {
                my $val = reverse my $key = "$c1$c2$c3$c4";
                   $val =~ y/ACGT/TGCA/;
                $table {$key} = $val;
            }
        }
    }
}

my %tmp; @tmp {@array} = ();
my @matches = grep {exists $tmp {$table {$_}}} @array;

print "@matches\n";

__END__