#!/usr/bin/perl
use warnings 'all';
use strict;
use Graph::Undirected;
use Graph::Writer::Dot;

my @areas = qw(
  America
  Britain
  Chile
);
my @verts = qw(
  Phone_Company
  Cellular_Networks
  Government
  Internet
  Rural_Users
);

my %graph; # Hash of Graph::Undirected objects.
foreach my $area (@areas) {
  $graph{$area} = Graph::Undirected->new();
  $graph{$area}->add_vertex($_) foreach @verts;
}

$graph{America}->add_edge(@verts[0,1]);
$graph{America}->add_edge(@verts[1,2]);
$graph{America}->add_edge(@verts[3,0]);
$graph{America}->add_edge('Government', 'Internet');

$graph{Britain}->add_edge(@verts[0,2]);
$graph{Britain}->add_edge(@verts[1,2]);
$graph{Britain}->add_edge(@verts[3,2]);

for ($graph{Chile}) {
  $_->add_edge(@verts[0,1]);
  $_->add_edge(@verts[0,2]);
  $_->add_edge(@verts[0,3]);
  $_->add_edge(@verts[1,2]);
  $_->add_edge(@verts[1,3]);
  $_->add_edge(@verts[2,3]);
}

my $writer = Graph::Writer::Dot->new();
foreach my $area (@areas) {
  $writer->write_graph($graph{$area}, "$area.dot");
}