note
Athanasius
<p>Hello [ragnarokPP], and welcome to the Monastery!</p>
<p>[tobyink] has shown you how to solve the problem with recursion, as you requested. Here is a non-recursive solution using the [mod://] module [mod://Set::Scalar]:</p>
<code>
#! perl
use Modern::Perl;
use Set::Scalar;
my $class_callback = sub { join(' ', sort { $a <=> $b } $_[0]->elements) };
Set::Scalar->as_string_callback($class_callback);
my @sets;
for (my $i = 0; <DATA>;)
{
chomp;
my $new_set = Set::Scalar->new(split /\s+/);
my $merged = 0;
for my $j (0 .. $i - 1)
{
if ($new_set->intersection($sets[$j]))
{
$sets[$j] = $sets[$j]->union($new_set);
$merged = 1;
last;
}
}
$sets[$i++] = $new_set unless $merged;
}
print '(', $_, ")\n" for @sets;
__DATA__
1 2 4
2 3 4
3 7
4 6
5 10 11 12 13
6
7 1
</code>
<p>Output:</p>
<code>
1:30 >perl 424_SoPW.pl
(1 2 3 4 6 7)
(5 10 11 12 13)
1:34 >
</code>
<p>Remember, the Perl motto is TMTOWTDI (There’s More Than One Way To Do It)!</p>
<p><b>Update:</b> The above code doesn’t merge fully on certain types of input. The following code fixes this:</p>
<code>
#! perl
use Modern::Perl;
use Set::Scalar;
my $class_callback = sub { join(' ', sort { $a <=> $b } $_[0]->elements) };
Set::Scalar->as_string_callback($class_callback);
my @sets;
for (my $i = 0; <DATA>; ++$i)
{
chomp;
$sets[$i] = Set::Scalar->new(split /\s+/);
}
print "Before merging:\n";
print '(', $_, ")\n" for @sets;
print "\n";
for my $i (reverse 1 .. $#sets)
{
for my $j (0 .. $i - 1)
{
if (defined $sets[$i] &&
defined $sets[$j] &&
$sets[$i]->intersection($sets[$j]))
{
$sets[$j] = $sets[$i]->union($sets[$j]);
$sets[$i] = undef;
}
}
}
@sets = grep { defined } @sets;
print "After merging:\n";
print '(', $_, ")\n" for @sets;
__DATA__
1 2 4
7 13
3 5 6
7 8
10 11 12
1 5
</code>
<p>Output:</p>
<code>
11:24 >perl 424_SoPW.pl
Before merging:
(1 2 4)
(7 13)
(3 5 6)
(7 8)
(10 11 12)
(1 5)
After merging:
(1 2 3 4 5 6)
(7 8 13)
(10 11 12)
12:17 >
</code>
<p>Hope that helps,</p>
<div class="pmsig"><div class="pmsig-968231">
<p>
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Athanasius <font color="#008000"><</font>[href://http://www.biblegateway.com/passage/?search=John%203:16&version=NLV|<font color="#008000">°</font>]<font color="#008000">(((><</font> <i>contra mundum</i>
</td>
<td align="right">
[href://http://translate.google.com.au/#la/en/Iustus%20alius%20egestas%20vitae%2C%20eros%20Piratica%2C|<b>Iustus alius egestas vitae, eros Piratica,</b>]
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