From: Warren Brown <warrenbrown@...>
Date: 2005-11-21T17:00:49+09:00
Subject: [SOLUTION] Euchre Hands (#55)

All,

    This quiz looked so simple I just couldn't resist putting in the
short amount of time needed to solve it.  Also, I love to play Euchre.

    I see other solutions trying very hard to make sure that two suits
of the same color do not appear next to each other.  As a Euchre player,
I would be quite upset if the order of the suits changed during play.
For example, if hearts were trump, and the hand is (9h 9s 9d 9c Tc), and
the 9s is played, the hand should stay (9h 9d 9c Tc), not be reordered
to (9h 9c Tc 9d).  I tend to always keep my suits in the same order (s h
c d) and simply rotate the order so that the trump suit is first (e.g.
(c d s h) if clubs are trump).

    I also made sure the routine works with fewer (or more) than five
cards since cards are actually played from the hand during a game.


----------------------------------------------------------------
# Constants
RANKS = 'AKQJT9'
SUITS = 'SHCD'
  
def euchre_sort(cards)
  # Split out trump
  trump = cards.shift

  # Quick and dirty validation
  trump_index = SUITS.index(trump[0,1].upcase)
  unless trump_index
    puts "Invalid trump (#{trump})."
    exit
  end
  cards.each do |card|
    if card !~ /^[#{RANKS}][#{SUITS}]$/i
      puts "Invalid card (#{card})."
      exit
    end
  end

  # Return sorted hand
  right_bower = "J#{SUITS[trump_index,1]}"
  left_bower = "J#{SUITS[trump_index - 2,1]}"
  [trump] +
    cards.sort_by do |card|
      upcase_card = card.upcase
      case upcase_card
        when right_bower then -2
        when left_bower  then -1
        else RANKS.index(upcase_card[0,1]) +
          10 * ((SUITS.index(upcase_card[1,1]) - trump_index) % 4)
      end
    end
end

puts euchre_sort(STDIN.read.split)
----------------------------------------------------------------


    This solution (minus error handling) is also very amenable to
golfing at 187 characters:

R='AKQJT9';S='shcd';i=$<.read.split;t=i.shift;x=S.index(t[0,1]
.downcase);r="J#{S[x,1]}";l="J#{S[x-2,1]}";puts(t,i.sort_by{|c|
c==r ?-2:c==l ?-1:R.index(c[0,1])+10*((S.index(c[1,1])-x)%4)})


    - Warren Brown