http://codeeval.com/open_challenges/7/

gistfile1.pl

my $file = $ARGV[0];

open FILE, "<", $file or die;
while (<FILE>){
	chomp;
	prefix_expression($_);
}
close FILE;

sub prefix_expression{
	my $str = $_[0];

	my ($symbols,$numbers) = $str =~ /^(.*?\D+)(.*)$/;

	my @symbols = split /\s+/, $symbols;
	my @numbers = split /\s+/, $numbers;

	my $c = 0;
	foreach(reverse @symbols){
		if ($_ eq '*'){
			$numbers[$c+1] = $numbers[$c] * $numbers[$c+1];
		}
		elsif ($_ eq '+'){
			$numbers[$c+1] = $numbers[$c] + $numbers[$c+1];
		}
		elsif ($_ eq '/'){
			$numbers[$c+1] = $numbers[$c] / $numbers[$c+1];
		}
		$c++;
	}

	#print "answer is $numbers[$c].\n";
	print $numbers[$c]."\n";
}