use warnings;
use strict;

sub calcit {
	my $in = shift;
	my %rules = (A => 1,B => 1,C => 0,D => 1);	
	my ($s,$s1,$s2) = (0)x3;
	while ($in=~/(\d+)([ABCD])/g) {	
		my ($n,$op) = ($1,$2);
		$s += $n * $rules{$op};
		$s1 += $n * $rules{$op}
			unless $op eq 'D' && $-[0]>0;
		$s2 += $n * $rules{$op}
			unless $op eq 'D' && $+[0]<length($in);
	}
	return ($s,$s1,$s2);
}

use Test::More;
is_deeply [calcit("2D40A2C1B4D")], [47,43,45], "2D40A2C1B4D";
is_deeply [calcit("2D40A2C1B")],   [43,43,41], "2D40A2C1B";
done_testing;