use strict;
use warnings;

my $usage = "Usage: $0 <infile.txt>\n";
my $infile = shift or die $usage;
use File::Basename;
my $DIR = dirname($infile);
my $outfile = $DIR . "/Results.txt" or die $usage;

open (my $data, "<", $infile) or die "There was a problem opening: $!";
my @primers = <$data>;
close $data;
chomp @primers;

use Algorithm::Combinatorics qw(combinations);
my $strings = \@primers;
my $iter = combinations($strings, 2);
open(my $fh, '>', $outfile);
while (my $c = $iter->next) {
    print $fh @$c, "\n";
}
print ("Finished. The results are located at $outfile\n\n");