use Algorithm::SetCovering;
 
my $alg = Algorithm::SetCovering->new(
    columns => 4,
    mode    => "greedy");
 
$alg->add_row(1, 0, 1, 0);
$alg->add_row(1, 1, 0, 0);
$alg->add_row(1, 1, 1, 0);
$alg->add_row(0, 1, 0, 1);
$alg->add_row(0, 0, 1, 1);
 
my @to_be_opened = (@ARGV || (1, 1, 1, 1));
 
my @set = $alg->min_row_set(@to_be_opened);
 
print "To open (@to_be_opened), we need ",
      scalar @set, " keys:\n";
 
for(@set) {
    print "$_: ", join('-', $alg->row($_)), "\n";
}