[QUIZ] Kalah (#58)
Ruby Quiz
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by Mark Van Holstyn
For my Computer Science class this month, we had to program a Kalah Player.
Sadly, we had to do our project in Java, but I ported the game code and the
sample players to ruby for this quiz though.
A good explanation of the game can be found at:
Your task is to create the best Kalah player you can. The player should look
like the following:
class HumanPlayer < Player
def choose_move
print 'Enter your move choice: '
gets.chomp.to_i
end
end
The 'choose_move' method is what the game will call to request a move from the
player. The Player class which you player should extend looks like so:
class Player
attr_accessor :name
attr_writer :game, :side
def initialize( name )
@name = name
end
def choose_move
if @side==KalahGame::TOP
(7..12).each { |i| return i if @game.stones_at?(i) > 0 }
else
(0..5).each { |i| return i if @game.stones_at?(i) > 0 }
end
end
end
The 'game' and 'side' attributes will be assigned by KalahGame. The side will
either be the constant KalahGame::TOP or KalahGame::BOTTOM. This is what you
will use to determine if you should be making moves from bowls 0-5 or 7-12 and
whether your Kalah is 6 or 13.
KalahMatch plays two games, one with each player on the each side of the board
and then averages their scores, so you must make you player be able to play both
on the top and the bottom.
Here's a sample game engine to get you started:
require 'Player'
require 'HumanPlayer'
class KalahMatch
def start( p1, p2 )
puts ''
puts '========== GAME 1 =========='
p1_score_1, p2_score_1 = KalahGame.new.play_game( p1, p2 )
if p1_score_1 > p2_score_1
puts p1.name+' won game #1: '+p1_score_1.to_s+'-'+p2_score_1.to_s
elsif p2_score_1 > p1_score_1
puts p2.name+' won game #1: '+p2_score_1.to_s+'-'+p1_score_1.to_s
else
puts 'game #1 was a tie: '+p1_score_1.to_s+'-'+p2_score_1.to_s
end
puts ''
puts '========== GAME 2 =========='
p2_score_2, p1_score_2 = KalahGame.new.play_game( p2, p1 )
if p1_score_2 > p2_score_2
puts p1.name+' won game #2: '+p1_score_2.to_s+'-'+p2_score_2.to_s
elsif p2_score_2 > p1_score_2
puts p2.name+' won game #2: '+p2_score_2.to_s+'-'+p1_score_2.to_s
else
puts 'game #2 was a tie: '+p1_score_2.to_s+'-'+p2_score_2.to_s
end
puts ''
puts '========== FINAL =========='
p1_final = p1_score_1+p1_score_2
p2_final = p2_score_1+p2_score_2
if p1_final > p2_final
puts p1.name+' won the match: '+p1_final.to_s+'-'+p2_final.to_s
elsif p2_final > p1_final
puts p2.name+' won the match: '+p2_final.to_s+'-'+p1_final.to_s
else
puts 'the match was tied overall : '+p1_final.to_s+'-'+p2_final.to_s
end
end
end
class KalahGame
NOBODY = 0
TOP = 1
BOTTOM = 2
def stones_at?( i )
@board[i]
end
def legal_move?( move )
( ( @player_to_move==TOP and move >= 7 and move <= 12 ) ||
( @player_to_move==BOTTOM and move >= 0 and move <= 5 ) ) and
@board[move] != 0
end
def game_over?
top = bottom = true
(7..12).each { |i| top = false if @board[i] > 0 }
(0..5).each { |i| bottom = false if @board[i] > 0 }
top or bottom
end
def winner
top, bottom = top_score, bottom_score
if top > bottm
return TOP
elsif bottom > top
return BOTTOM
else
return NOBODY
end
end
def top_score
score = 0
(7..13).each { |i| score += @board[i] }
score
end
def bottom_score
score = 0
(0..6).each { |i| score += @board[i] }
score
end
def make_move( move )
( puts 'Illegal move...' ; return ) unless legal_move?( move )
stones, @board[move] = @board[move], 0
pos = move+1
while stones > 0
pos+=1 if( (@player_to_move==TOP and pos==6) ||
(@player_to_move==BOTTOM and pos==13) )
pos = 0 if pos==14
@board[pos]+=1
stones-=1
pos+=1 if stones > 0
end
if( @player_to_move==TOP and pos>6 and pos<13 and @board[pos]==1 )
@board[13] += @board[12-pos]+1
@board[12-pos] = @board[pos] = 0
elsif( @player_to_move==BOTTOM and pos>=0 and pos<6 and @board[pos]==1 )
@board[6] += @board[12-pos]+1
@board[12-pos] = @board[pos] = 0
end
if @player_to_move==TOP
@player_to_move = BOTTOM unless pos == 13
else
@player_to_move=TOP unless pos == 6
end
end
def display
puts ''
top = ' '
[12,11,10,9,8,7].each { |i| top += @board[i].to_s+' ' }
puts top
puts @board[13].to_s + ' ' + @board[6].to_s
bottom = ' '
(0..5).each { |i| bottom += @board[i].to_s+' ' }
puts bottom
puts ''
end
def reset
@board = Array.new( 14, 4 )
@board[6] = @board[13] = 0
@player_to_move = BOTTOM
end
def play_game( bottom, top )
reset
bottom.side = BOTTOM
top.side = TOP
top.game = bottom.game = self
puts bottom.name+' starts...'
display
until game_over?
puts ''
if @player_to_move == TOP
move = top.choose_move
puts top.name+' choose move '+move.to_s
else
move = bottom.choose_move
puts bottom.name+' choose move '+move.to_s
end
make_move( move )
display
end
[top_score, bottom_score]
end
end
p1 = Player.new( 'Player 1' )
p2 = Player.new( 'Player 2' )
KalahMatch.new.start( p1, p2 )
Adam Shelly
> def play_game( bottom, top )
> reset
## Play the game here...
> [top_score, bottom_score]
> end
It's returning the scores in the reverse order of the players..
So in KalahMatch, it reports the wrong winnner:
> puts '========== GAME 1 =========='
> p1_score_1, p2_score_1 = KalahGame.new.play_game( p1, p2 )
I think the last line of KalahGame#play_game should be:
[bottom_score, top_score]
-Adam
James Edward Gray II
I agree. That looks like a bug.
Thanks for pointing it out.
James Edward Gray II
P.S. If anyone enhances the game engine and wants to share the
changes, I don't consider that a spoiler...
Kero
You want bugs? There's bttom or bottm somewhere in the code.
Bill Guindon
> > I agree. That looks like a bug.
>
> You want bugs? There's bttom or bottm somewhere in the code.
Yep, in the 'winner' code:
def winner
top, bottom = top_score, bottom_score
if top > bottm
--
Bill Guindon (aka aGorilla)
James Edward Gray II
> On 12/9/05, Kero <ke...@chello.single-dot.nl> wrote:
>>> I agree. That looks like a bug.
>>
>> You want bugs? There's bttom or bottm somewhere in the code.
>
> Yep, in the 'winner' code:
>
> def winner
> top, bottom = top_score, bottom_score
> if top > bottm
Ah yes. That's another one. Thanks you two.
James Edward Gray II
Stephen Waits
>
> Ah yes. That's another one. Thanks you two.
Is there a place where we can easily grab the most recent version?
Thanks,
Steve
James Edward Gray II
David Balmain
class KalahGame
attr_reader :board, :player_to_move
def initialize_copy(other_game)
super
@board = other_game.board.dup
end
end
Cheers,
Dave
James Edward Gray II
> Could we add this enhancement. It makes searching a lot easier.
>
> class KalahGame
> attr_reader :board, :player_to_move
>
> def initialize_copy(other_game)
> super
> @board = other_game.board.dup
> end
> end
I'm pretty sure I did what you wanted. Double check me please.
David Balmain
Perfect. Thanks. Sorry I wasn't very clear. :)
Cheers,
Dave
> James Edward Gray II
>
>
Jannis Harder
of constants like TOP = 1...
--
Jannis
James Edward Gray II
> I think one should use symbols (:top :bottom) instead
> of constants like TOP = 1...
While that probably is more Rubyish, let's try to avoid style-only
changes, just so we're not forcing people to download the code again
and break their solutions.
James Edward Gray II
Christer Nilsson
Benedikt Heinen
> Rob, I think you forgot the code.
I don't think he did - there is a solution.tar.gz attached to his mail:
beh@myhost:/tmp/sol $ tar xfvz ~/solution.tar.gz
match.rb
players.rb
state.rb
strategies.rb
beh@myhost:/tmp/sol $ wc *.rb
176 526 4122 match.rb
107 263 2159 players.rb
198 587 4226 state.rb
44 110 978 strategies.rb
525 1486 11485 total
beh@myhost:/tmp/sol $
Looks fine from here... ;-)
Benedikt
ALLIANCE, n. In international politics, the union of two thieves who
have their hands so deeply inserted in each other's pockets that
they cannot separately plunder a third.
(Ambrose Bierce, The Devil's Dictionary)
Christer Nilsson
Christer Nilsson
I didn't get the email and the contribution by Rob is not available at
either.
David Balmain
To you only.
Looks like you are setting up a nice little framework there. Since you
are going to the effort, you might want to have a look at my solution;
MyPlayer won the match: 71-25
MyPlayer took 2.249866 seconds, Standard took 93.019248 seconds
Not sending this to brag. Actually, I think your code is a lot nicer.
I'm betting James will just ignore my solution in his quiz summary
again. Fair enough too. It's not very rubyish and it is a bit complex
but it does a good job. If you'd like to clean it up and incorporate
it into your framework, please do. And since you are using gdbm, maybe
you'll even be able to get my transposition tables to work. Currently
I have to refresh them each turn (which would be completely pointless
if I wasn't using MTD(f)). If you want to read more about the MTD(f)
algorithm I found a good explanation here;
http://www.cs.vu.nl/~aske/mtdf.html
Anyway, hopefully my code will be of interest to someone. ;-)
Cheers,
Dave
PS: if you didn't find my solution in the mailing list, it's here;
http://www.davebalmain.com/pages/kalah
On 12/12/05, Rob Leslie <r...@mars.org> wrote:
> Here's my solution. I'm still playing with it, but I'm posting it now
> for the benefit of others to look at.
>
> The solution is divided into strategies and players. Strategies are
> used to estimate the value of any particular board configuration to a
> player without any deep recursion or other lengthy operations. The
> only strategy I have now is BasicStrategy.
>
> Players implement a tactic for finding the best move based on the
> strategy. StandardPlayer uses a 6-ply alpha-beta search, and plays
> fairly well. The ply depth can be changed by modifying the DEPTH
> constant.
>
> ThreadedPlayer is an experimental time-limited player using a
> multithreaded search. It doesn't tend to play as well or as fast as
> StandardPlayer. CachingPlayer is an experimental GDBM-based caching
> player I wrote in an attempt to improve StandardPlayer's performance.
>
> RandomPlayer simply plays random moves, and has been useful for testing.
>
> To play, you can:
>
> ruby -r ./match.rb -e 'run(StandardPlayer, RandomPlayer)'
>
>
>
>
> --
> Rob Leslie
> r...@mars.org
>
>
>
>
>
>
David Balmain
Errr.... Since it went out to the world I just want to be clear on one
thing. The point I was trying to make about not being included in the
quiz summary was that my solution isn't very Rubyish and is more
interesting from and algorithms perspective than a coding perspective.
I hope that's clear. :-\
Damn, how embarrassing.
Stephen Waits
On Dec 12, 2005, at 4:09 AM, David Balmain wrote:
> Anyway, hopefully my code will be of interest to someone.
Dave,
I should have let you know when I first saw your solution, but I
found it very interesting. I only briefly looked at your code, but
am really thankful that you pointed me to the MTD(f) algorithm. The
last time I looked at dealing with game move trees, this algorithm
wasn't around, and I probably wouldn't have learned about it were it
not for your Solution.
Thanks,
Steve
David Balmain
Great :-)
I only learned about it over the weekend too. I'm hoping someone will
be able to improve on my solution. Game playing algorithms can be a
lot of fun. I wish I had more time to play around with stuff like
this.
Dave
> Thanks,
> Steve
>
>
>
James Edward Gray II
> Errr.... Since it went out to the world I just want to be clear on one
> thing. The point I was trying to make about not being included in the
> quiz summary was that my solution isn't very Rubyish and is more
> interesting from and algorithms perspective than a coding perspective.
> I hope that's clear. :-\
No worries, you didn't offend me. ;)
There's no real science about how I choose a solution to discuss. I
read them all and when one inspires me, I talk about it. Very
systematic, as you can see. ;)
I will tell you that I notice I'm getting pickier and pickier about
code length though. I'm certainly not looking to encourage golf
(that's pretty much the opposite of what Ruby Quiz stands for) and
I'm not trying to slack off on summary work, but I truly believe
correct Ruby involves "Writing less code."
So a good tip for catching my eye is not using five lines when two
will do. Sprinkle in a few clever Ruby style idioms and you've got a
better than average chance of getting singled out.
Just FYI.
James Edward Gray II
Chad Perrin
>
> I will tell you that I notice I'm getting pickier and pickier about
> code length though. I'm certainly not looking to encourage golf
> (that's pretty much the opposite of what Ruby Quiz stands for) and
> I'm not trying to slack off on summary work, but I truly believe
> correct Ruby involves "Writing less code."
If you have to rewrite something three times to get it down to two lines
instead of five (as typically happens in golf), you're not "writing less
code" anyway. Rewriting it once to idiomize the code in a Rubylike
style to make it more readable and maintainable can reduce the amount of
code needed to maintain it later, so it's sorta like an investment, so
if rewriting it once to get five lines down to three in a Rubylike style
is probably worth being called "writing less code", but golf, I would
say is not: it's gratuitous.
That's not to say I think golf is bad. Gratuitous stuff like that can
be highly entertaining. It's just not the same as "writing less code".
In other words, I definitely tend to like the way you handle it.
Apparently, being a little sick has given me diarrhea of the mouth.
Forgive my rambling.
--
Chad Perrin [ CCD CopyWrite | http://ccd.apotheon.org ]
unix virus: If you're using a unixlike OS, please forward
this to 20 others and erase your system partition.
David Balmain
Cool. And this is the way it should be. That's the reason I read your
summary every week. I use different resources for finding out the
latest and greatest algorithms. Anyway, I can't wait for the book. 3
months to go. :-)
Adam Shelly
Dave scored 1057 points in 409.138 seconds
AHistoryKalahPlayer scored 893 points in 512.221 seconds
RemoveRightKalahPlayer scored 892 points in 0.061 seconds
APessimisticKalahPlayer scored 807 points in 1735.01 seconds
DeepScoreKalahPlayer scored 789 points in 0.296 seconds
StandardPlayer scored 757 points in 4310.645 seconds
CachingPlayer scored 754 points in 4560.485 seconds
ScoreKalahPlayer scored 735 points in 0.139 seconds
ThreadedPlayer scored 621 points in 3582.531 seconds
RemoveRandomLowKalahPlayer scored 516 points in 0.031 seconds
RemoveRandomHighKalahPlayer scored 482 points in 0.032 seconds
RandomPlayer scored 480 points in 0.0 seconds
RemoveHighKalahPlayer scored 454 points in 0.03 seconds
Player scored 433 points in 0.016 seconds
RemoveLowKalahPlayer scored 410 points in 0.0 seconds
I've had no luck improving my "smart" algorithms, so I'm submitting
this new player.
Wins every time.
class Cheater < Player
def choose_move
k = (@side==KalahGame::TOP) ? 13 : 6
@game.board.each_index {|i|
unless [6,13].include? i
@game.board[k]+=@game.board[i]
@game.board[i]=0
end
}
@game.board[k]-=1
@game.board[k-1]=1
k-1
end
end
-Adam
On 12/12/05, David Balmain <dbalm...@gmail.com> wrote: