#!/usr/bin/perl

# Starting with your data structure from Exercise 2, rewrite the
# coconet.dat file so that it's in the same format, but sorted by source
# machine. Report each destination machine once per source machine along
# with total bytes transferred. The destination machines should be indented
# under the source machine name and be sorted by the machine name:
#
# ginger.hut
# 	maryann.hut 13744
# professor.hut
# 	gilligan.hut 1845
# 	maryann.hut 90
# thurston.howell.hut
# 	lovey.howell.hut 97560
# ...

use v5.24;
use warnings;
use strict;
use utf8;

my %hosts;
while (<>) {
	next if (/\A\s*#/);
	my ($src, $dst, $bytes) = split;
	$hosts{$src}{$dst} = $bytes;
}
sub sum {
	my $hashref = shift;
	my $total;
	foreach (keys %{$hashref}) {
		$total += $hashref->{$_};
	}
	return $total;
}
foreach my $src (sort { sum($hosts{$b}) <=> sum($hosts{$a}) } keys %hosts) {
		print "$src\n";
	foreach my $dst (sort { $hosts{$src}{$b} <=> $hosts{$src}{$a} }
			keys %{$hosts{$src}}) {
		print "    $dst $hosts{$src}{$dst}\n";
	}
}