#!/usr/bin/perl -T
use strict;
use diagnostics;

# --

sub get_cpu {
	my $servername	= shift;
	my %cpu	= (
		server1 => 10,
		server2 => 20,
		server3 => 5,
		server4 => 15,
	);
	return $cpu{$servername};
};

# --

my %servers	= (
	server1 => 'cluster1',
	server2 => 'cluster1',
	server3 => 'cluster2',
	server4 => 'cluster2',
);

my %clusters;
foreach my $servername (keys %servers) {
	$clusters{$servers{$servername}}	+= get_cpu($servername);
};

print "$_:\t".($clusters{$_}/2)."\n" foreach sort keys %clusters;