A hash is not the right structure for this problem. You should use an array:

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

and you can sort it as:

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

or if that sort results too slow:

use Sort::Key qw(nkeysort_inplace);

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

Then, you have to look for the N largest areas. It can be done recursively: get the biggest rectangle and look for the N-1 largest, non-overlapping areas.

BTW, "the N largest boxes" is not very precise. Which is larger, a set of rectangles with areas (9, 1) or another with (7, 6)?

I suppose you want to maximize the total area:

# 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);
}
[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.