#!/usr/bin/perl
use Graph::Undirected;
use strict; use warnings;
my $g = Graph::Undirected->new;
my @key_array = 'a' .. 'z';
my @set_array = ( ['a', 'b'],  ['e','f'], ['f','g'] );

$g->add_vertex( $_ ) for @key_array;
$g->add_edge( $_->[0], $_->[1] ) for @set_array;

print "$_\n" for  
    sort { length($b) <=> length($a) || $a cmp $b }
    map {join( ',',  @$_) } 
    $g->connected_components;