use strict;
use Data::Dumper;

my $start;

sub add{
	my $root = shift;
	my $level = shift;
	my @items = @_;
	if(!@items) {return;}
	#print "level = $level\n";
	while(@items) {
		my $first = shift @items;
		$root->{$first}->{count}++;
		#print "\t" x $level . "first = " . $first . ", values = " . join(',',@items)."\n";
		add($root->{$first}->{children}, $level+1, @items);
	}
}

add($start, 1, 1..3);
add($start, 1, 1..2);

print Dumper($start);

##</code><code>##

$VAR1 = {
          '1' => {
                   'children' => {
		                    '2' => {
				              'children' => {
					                      '3' => { 'count'=>1}
							    },
						'count' => 2},
				    '3' => {'count' => 1}
				    },
                   'count' => 2
                 },
          '3' => {
                   'count' => 1
                 },
          '2' => { 'children' => {
	  			'3' => {
					'count' => 1
				}
			},
                   'count' => 2
                 }
        };