my @box;
for (...) {
  my ($NetName, $MinX, $MinY, $MaxX, $MaxY) = ...;
  push @box, [$NetName,
              $MinX, $MinY, $MaxX, $MaxY,
              ($MaxX - $MinX) * ($MaxY - $MinY)];
}

##</code><code>##

@box = sort { $a->[5] <=> $b->[5] } @box;

##</code><code>##

use Sort::Key qw(nkeysort_inplace);

nkeysort_inplace { $_->[5] } @box;

##</code><code>##


# untested!

my ($area, @best) = n_largest_boxes(\@box, $n);

sub overlap {
  my ($box1, $box2) = @_;
  return !( $box1->[3] < $box2->[1] or
            $box1->[1] > $box2->[3] or
            $box1->[4] < $box2->[2] or
            $box1->[2] > $box2->[4] )
}

sub n_largest_boxes {
  my ($boxes, $n, $start, @acu) = @_;
  my $max = 0; # area for the biggest set of boxes found
  my @max;     # rectangles on the biggest set
  for ($i = $start || 0;
       $i + $n <= @$boxes and $boxes->[$i][5] * $n > $max;
       $i++) {
    my $box = $boxes->[$i];
    next if grep overlap($_, $box), @acu;
    if ($n > 1) {
      my $max1, @max1 = n_largest_boxes($boxes, $i+1, $n-1,
                                        @acu, $box);
      if ($max1 and $max1 + $box->[5] > $max) {
        $max = $max1 + $box->[5];
        @max = ($box, @max1);
      }
    }
    else {
      return ($box->[5], $box);
    }
  }
  return ($max, @max);
}