Ok, dpuu suggested Graph, which I recommend. This does it:

#!/usr/bin/perl -w
use strict;

use Graph::Undirected;
my $net = Graph::Undirected->new;
while (<DATA>) {
    $net = $net->add_edge( split );
}

use Data::Dumper;
print Dumper($net);

__END__
0 1
1 2
1 3
1 4
2 4
4 5

[download]

Graph.pm takes care of circular references for you.

After Compline,
Zaxo

In reply to Re: Re: H of A optimization by Zaxo
in thread H of A optimization by abitkin

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