From: Robin Stocker <robin@...>
Date: 2005-11-20T23:53:53+09:00
Subject: [QUIZ SOLUTION] Euchre Hands (#55)

Hi

This one seemed pretty easy, so I gave it a try.

My first idea was to solve the whole sorting in the <=> method of the 
Card class. But it was too confusing this way, because I had to include 
all possible comparisons. Also the Card itself had to know what the 
trump suit was.

Then I tried a different approach. I wrote a Card#weighting method which 
returned a number, for trump jack a 41, for trump color jack a 40, and 
so on. Then i sorted the card array with sort_by and the weighting. But 
I wasn't satisfied yet, because again, the card had to know what suit 
was trump. And the numbering was ugly, too. :)

So my final idea was to just implement the <=> method for sorting 
without regard to trump. Then in my Hand class, which knows about the 
trump, I wrote a sort! method for the sorting with regard to trump suit.

Now I'm interested to see other solutions :)

   Robin Stocker


module Euchre

   class Hand
     attr_accessor :cards

     def initialize( trump )
       @cards = []
       @trump = Card.new( trump )
     end

     def <<( card )
       @cards << card
     end

     def sort!
       @cards =
         # First the trump jack..
         @cards.select{ |c| trump_suit?(c) and c.jack? } |
         # then the jack of the trump color..
         @cards.select{ |c| trump_color?(c) and c.jack? } |
         # then all the trump cards..
         @cards.select{ |c| trump_suit?(c) }.sort.reverse |
         # then a different color, so the colors alternate..
         @cards.select{ |c| !trump_color?(c) and
           c.suit =~ /d|c/ }.sort.reverse |
         # then the cards with the same color as the trump..
         @cards.select{ |c| trump_color?(c) }.sort.reverse |
         # and finally the rest.
         @cards.sort.reverse
     end

     def trump_suit?( card ) card.suit == @trump.suit end
     def trump_color?( card ) card.color == @trump.color end

     def to_s
       @cards.join("\n")
     end
   end

   class Card
     attr_accessor :suit, :face

     Suits = ['d', 'h', 'c', 's']
     Faces = ['9', 'T', 'J', 'K', 'A']
     Colors = {'d' => :red, 'h' => :red, 'c' => :black, 's' => :black}

     def initialize( suit, face=nil )
       @suit = suit.downcase
       @face = face.upcase if face
     end

     def jack?() @face == 'J' end
     def color() Colors[@suit] end

     # Sort first by suit and then by face.
     def <=>( other )
       rel = Suits.index(@suit) - Suits.index(other.suit)
       rel = Faces.index(@face) - Faces.index(other.face) if rel == 0
       rel
     end

     def to_s
       @face + @suit
     end
   end

end


if __FILE__ == $0
   lines = readlines

   trump = lines.shift.slice(/\w+/)
   hand = Euchre::Hand.new(trump[0,1])

   lines.join.scan(/(\w)(\w)/) do |face, suit|
     hand << Euchre::Card.new(suit, face)
   end

   hand.sort!
   puts trump
   puts hand
end