Guess what ... a new minigolf just started

[Terje Kristensen]

Yep, your eyes does not deceive you. We have actually started a new golf
here at http://terje2.perlgolf.org

I hope there still is some perl golfers out there itching for a new
challenge.

The task this time is called "beads".

Terje and Mtve

[Shlomi Fish]

Thanks for the new golf!

In any case, there's an exploitable "feature" in the count sub-routine in the
testsuite:

<<<
sub count {
my ($hole, $tie) = @_;
local $_ = slurp($props{$hole}{work}, $binary);
if (/^\#!/) {
s/^\#![\t ]?\S+// && s/\n//;
}
s/\s*\z//; <--------
my $md5 = md5_hex($_);
my $score = length;
my $normal = $score ? y/ -~\t\n// / $score : 1;
if (defined($tie)) {
defined(my $code = $tie_map{lc($tie)}) ||
die "Unknown tie function $tie\n";
$score += $code->($_, $score)/$nr_ties if $score;
$ties++;
}
return ($score, $md5, $normal*100);
}

>>>

What happens is that trailing whitespace is removed. But one can use it to
encode the entire program, no matter how long it is, and get a 25 characters
solution. Like this:

<<<
#!/usr/bin/perl

use strict;
use warnings;

use IO::All;

my @code = io("beads.pl")->getlines();

my $bleach = join("", unpack("b*", ";$code[1]"));
$bleach =~ s!0! !g;
$bleach =~ s!1!\t!g;

io("bleach/beads.pl")->print(
qq{open 0;eval pack"ab*",<0>\n$bleach}
);
>>>

This is not my original idea: Piotr Fusik used it for his solution in the last
kernelpanic.pl Perl golf.

But I suggest issuing a new beadstest.pl file so that people won't all submit
25-characters solutions and this would be more of a real golf. It should be
noted in the subsequent golfs as well.

Regards,

Shlomi Fish (who would now be working hard on optimizing his relatively long
solution)

---------------------------------------------------------------------
Shlomi Fish shl...@iglu.org.il
Homepage: http://www.shlomifish.org/

95% of the programmers consider 95% of the code they did not write, in the
bottom 5%.

[Stefan `Sec` Zehl]

On Fri, Sep 09, 2005 at 13:39 +0300, Shlomi Fish wrote:
> Regards,
>
> Shlomi Fish (who would now be working hard on optimizing his
> relatively long solution)

It took me quite some time to reach you, but after spending some more
hours playing around, I finally found the trick for a shorter solution,
after which I was able to shed 20 more characters quickly.

Lets see if anyone can top the 37 ;)

CU,
Sec
--
"There was a clothing company there called OpenBSD, later somebody
told me they make an operating system as well."
-- Poul-Henning Kamp's EuroBSD Conference review.

[Stefan `Sec` Zehl]

On Fri, Sep 09, 2005 at 20:34 +0200, Stefan `Sec` Zehl wrote:
> On Fri, Sep 09, 2005 at 13:39 +0300, Shlomi Fish wrote:
> > Regards,
> >
> > Shlomi Fish (who would now be working hard on optimizing his
> > relatively long solution)
>
> It took me quite some time to reach you, but after spending some more
> hours playing around, I finally found the trick for a shorter solution,
> after which I was able to shed 20 more characters quickly.
>
> Lets see if anyone can top the 37 ;)

Awww. I'm sooo stupid. After seeing the post-mortem, i realize that I
actually had the 36 char version in my editor at one point, I just
didn't notice it, because I thought it was still 37 chars %). I must
remember to run each and every version through the test script.

CU,
Sec
--
At least in Norway, I know people have been put in jail for following
the prime directive instead of helping. -- <a...@flying.broomstick.com>

[Ton Hospel]

In article <200509091339....@iglu.org.il>,

Shlomi Fish <shl...@iglu.org.il> writes:
> In any case, there's an exploitable "feature" in the count sub-routine in the
> testsuite:
>
> <<<
> sub count {
> my ($hole, $tie) = @_;
> local $_ = slurp($props{$hole}{work}, $binary);
> if (/^\#!/) {
> s/^\#![\t ]?\S+// && s/\n//;
> }
> s/\s*\z//; <--------
> my $md5 = md5_hex($_);
> my $score = length;
> my $normal = $score ? y/ -~\t\n// / $score : 1;
> if (defined($tie)) {
> defined(my $code = $tie_map{lc($tie)}) ||
> die "Unknown tie function $tie\n";
> $score += $code->($_, $score)/$nr_ties if $score;
> $ties++;
> }
> return ($score, $md5, $normal*100);
> }
>
>>>>
>
> What happens is that trailing whitespace is removed. But one can use it to
> encode the entire program, no matter how long it is, and get a 25 characters
> solution.

In fact the space removal code is there intentionally because in
previous golfs people actually had programs counted with extra chars
because they forgot to remove trailing newlines/spaces (which can be hard
to spot in some editors). This was considered unfair to these players and
on popular request I added the space stripping.

Nobody said that what the test program says is your official score, just
as passing the tests doen't make your program officially correct.
The generic rules at http://www.xs4all.nl/~thospel/golf/rules.html is
where scoring is defined for most minigolfs, and they define the score
as total number of bytes, and then it's clear all these end spaces
count.

So if someone submits a program that uses end spaces to encode the
solution, simply smile at him and put him at a score that is his total
byte length.

I could make a patch for the gentester, but I think it would cause
more problems than it solves.