#!/usr/bin/perl
use warnings;
use strict;

use Graph;

my @links = (qw( A   C
                 C   E
                 D   C
                 L   G
                 J   K
                 O   P
                 I   M
                 L   K
              ));

my $g = 'Graph::Undirected'->new;
$g->add_edge(splice @links, 0, 2) while @links;
print "@$_\n" for $g->connected_components;