[LRUG] ShRUG Golf update

Thu May 12 02:54:05 PDT 2011

Now that I remember:

Hole number 2 was about ordering a sentence by the second character of each
word, my solution was:

sentence.split(' ').sort{ |a, b| a[1] <=> b[1] }.join ' '

It could be shortened into:

sentence.split(' ').sort_by{ |a| a[1] }.join ' '

On 12 May 2011 10:44, James Adam <james at lazyatom.com> wrote:

> I thought that I left with is how we always seemed driven towards
> functional rather than procedural solutions. This could just be a
> consequence of the particular problems we had to solve, which were
> almost all simple input transformations, but I suspect the shortest
> solution to any problem would include a lot of functional operations.
> They really are powerful.
>
> In hindsight this seems obvious, but by the end of the evening I was
> desperately trying to think of how to save characters by aliasing
> `inject` to something, since we used it in almost every single hole.
>
> Oh, also: a single-letter constant is one character shorter than "-1" :)
>
> - James
>
> On 12 May 2011 10:41, Aanand Prasad <aanand.prasad at gmail.com> wrote:
> > 1. The (a ? b : c) ternary operator does the expected thing if you chain
> it
> > and leave out parentheses, making it shorter than if/elsif/else, even if
> it
> > looks terrifying:
> > s > 3600 ? "more than an hour" : s > 60 ? "more than a minute" : s > 1 ?
> > "more than a second" : "GET OUT OF THE WAY"
> > 2. a[-1] is 1 character shorter than a.last.
> > On Thursday, May 12, 2011 at 10:30 AM, Murray Steele wrote:
> >
> > I think it might be useful to do a bit of a review of things people
> learned
> > while doing rubygolf*.  We didn't have time on the night and it sounds
> like
> > that might have been at good part of the SHRUG meeting.
> > I'll start with some snippets that I learned / remembered:
> > 1. Enumerable#inject doesn't need a block, it actually takes 2 params, a
> > initial value and a symbol as an argument.  Each iteration the symbol is
> the
> > method that'll be called on the accumulator and passed the current
> element.
> >  Also if you don't supply an initial element then it'll use the first
> > element of the enumerable.  So you can turn
> > array.inject(0) {|s, i| s + i}
> > into
> > array.inject(:+)
> > 2. Procs and Lambdas can be invoked via .[] rather than .call.
> > 3. There are millions of ways of defining methods on something.  Luckily,
> > the tests don't say that Golf needs to be a class, so we can define Golf
> as
> > a constant and just add methods to it.  So we can turn:
> > class Golf
> >   class << self
> >     def hole1
> >       ...
> >     end
> >   end
> > end
> > into:
> > class << Golf = ''
> >   def hole1
> >     ...
> >   end
> > end
> > (e.g open up the metaclass of Golf, which happens to be a constant of an
> > empty string, rather than a class.  Works because assignment (Golf = '')
> has
> > higher precendence than class-opening-up (class << Golf).
> > I tried to shave 1 character by setting Golf to be numbic constant:
> > class << Golf = 1
> >   def hole1
> >     ...
> >   end
> > end
> > But it doesn't work because Fixnums have no metaclass.  Depending on what
> > you do to try and add the methods you get various errors like:
> > TypeError: no virtual class for Fixnum
> > or
> > TypeError: can't define singleton method "hole1" for Fixnum"
> > I found this surprising, (and I think I've come across it before, and was
> > surprised then too) as I always believed the "everything is an object"
> > mantra of Ruby, assuming everything was the same under the hood.  Turns
> out
> > that while it's still true that everything is an object, some objects are
> > clearly more objecty than others.
> > I doubt I'd ever want to use any of these tricks in production code (as
> > someone said, it's can be far from readable), but I don't think it's been
> > just a toy exercise.  In trying to shave characters off my solution I've
> > been pushing the boundaries of what Ruby can and can't do.  This in turn
> > helps solidify my understanding of the object-model and syntax parser.
> > So, anyone else want to share what they learned?
> > Muz
> > *: I'm still working on mine and while I don't want to look directly at
> > other solutions, I'm happy to be given inspiration by discussing
> > techniques**.
> > **: Yes I know this makes no sense.
> >
> > On 10 May 2011 15:03, Andrew McDonough <andrew at andrewmcdonough.co.uk>
> wrote:
> >
> > Thanks James.  I'm glad that ShRUG enjoyed it.  We were a bit short on
> > time at LRUG, with less than an hour available for coding.  Four teams
> > completed the course, and our winner was Tomasz Wegrzanowsk (@t_a_w),
> > who was working on his own, and managed 704 characters
> > (http://j.mp/lbcXV2).  Second place was @zuppr, @jamiemill @morticed
> > and @aanand who came a close second in with 843 chars
> > http://j.mp/mBjfJU, third place was  @danlucraft, @nfelger, Jordi,
> > Dan, Tony, Steve and Keith who completed the course in 883 chars
> > http://j.mp/jHhbWU and finally one other anonymous team completed the
> > course with 1208 characters (if this was you, please let us know who
> > you are).  The winner, Tomasz (http://j.mp/lSsmJd), was presented with
> > a trophy (http://j.mp/iRFwGP) and the second placed team got medals.
> > There are still four medals left, which I will award at the next LRUG
> > to the four people who produce the best solutions (not necessarily the
> > shortest ones), so there's still something to play for if you didn't
> > come along on the evening.
> >
> > There appears to have been a lot of work done since to get the
> > character counts down even further, in particular from Paul Battley
> > with some help from Tom Stuart.  Their commit log is worth looking
> > through:
> >
> > https://github.com/threedaymonk/rubygolf/commits/master
> >
> > They got the solution down to 654 characters, before realising they
> > could exploit my "whitespace isn't counted" rule to encode their
> > solution in spaces and newlines, and then simply decode and exec.
> > This brought the solution down to 37 characters.  He gets one of the
> > four medals.  Genius:
> >
> > https://github.com/threedaymonk/rubygolf/blob/master/lib/golf.rb
> >
> > I have put the introductory presentation I made up on heroku:
> >
> > http://rubygolf-presentation.heroku.com
> >
> > Skills Matter have published some photos of the evening:
> >
> >
> http://www.flickr.com/photos/skillsmatter/5704350908/in/set-72157626683669388/
> >
> > I will follow up later with some analysis of the solutions and some of
> > the tricks and techniques used, but for now, you can look through the
> > various solutions that were submitted:
> >
> > https://github.com/andrewmcdonough/rubygolf/network
> >
> > Congratulations to ShRUG - you guys did really well completing the
> > course with so few characters.
> >
> > Andrew
> >
> > ---
> > Andrew McDonough
> > CTO, Tribesports
> > http://tribesports.com
> >
> >
> > On 10 May 2011 13:59, James Almond <james at jamesalmond.com> wrote:
> >> Hi all,
> >> As promised, an update on ShRUG's progress with the Ruby Golf night we
> ran
> >> in parallel with LRUG.
> >> Firstly, I managed to fork the repository before the 7th hole was added
> >> and
> >> nobody noticed until a fair amount of time into the evening so we
> >> completed
> >> the course without it. We also worked with a slightly lighter and RSpec
> >> 2 compatible runner, but all specs and counting mechanisms stayed the
> >> same.
> >> Everyone had 1.9.2 installed and favoured it, so we went with that over
> >> 1.8.7. I think we were still pretty close to what you were running. We
> had
> >> around 5 pairs of 2.
> >> Our lowest team effort on the night was 592 (with hole 7
> >> missing): https://github.com/ianwhite/rubygolf/blob/master/lib/golf.rb
> >> A group discussion and edit took the count down to
> >>
> >> 522:
> https://github.com/shruggers/rubygolf/blob/ecd0b312bfb9707b6debfc01062eab5e39d5f95a/lib/golf.rb
> >> A bit of post-ShRUG editing and adding hole 7 our final team count was
> >> 604: https://github.com/shruggers/rubygolf/blob/master/lib/golf.rb
> >> The discussion and collating of the results at the end was good fun and
> >> also
> >> made it one of the latest running ShRUG meetings I can remember.
> >> Everyone had a great evening, and learnt something new. Thanks to Andrew
> >> (and anybody else who contributed) for the holes, much appreciated! The
> >> #rubygolf radio silence from Sheffield was because everyone was too busy
> >> attempting the holes, sorry about that.
> >> James
> >> _______________________________________________
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> >>
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