Re: to find inter-connected items

[Athanasius]

This is an interesting problem. choroba’s excellent solution can be simplified somewhat by using the Set::Scalar module:

#! perl
use strict;
use warnings;
use Set::Scalar;

my @a = (1, 1, 2, 3, 4, 4, 8,  8);
my @b = (3, 4, 3, 5, 6, 7, 9, 10);
my @sets;
@a == @b or die "The arrays are of different lengths.\n";

for (0 .. $#a)
{
    my ($ai, $bi, $found) = ($a[$_], $b[$_], 0);

    for (@sets)
    {
        if ($_->has($ai) || $_->has($bi))
        {
            $found = 1;
            $_->insert($ai, $bi);
            last;
        }
    }

    push @sets, Set::Scalar->new($ai, $bi) unless $found;
}

OUTER: for my $i (reverse 1 .. $#sets)
{
    for my $j (reverse 0 .. $i - 1)
    {
        unless ($sets[$i]->intersection($sets[$j])->is_empty())
        {
            $sets[$j] = $sets[$j]->union($sets[$i]);
            splice(@sets, $i, 1);
            redo OUTER;
        }
    }
}

print "$_\n" for @sets;

Update: Added block labelled OUTER to merge sets having common elements.

Output:

14:35 >perl 366_SoPW.pl
(1 2 3 4 5 6 7)
(10 8 9)

14:36 >

Hope that helps,