From: James Edward Gray II <james@...>
Date: 2005-10-19T07:18:25+09:00
Subject: Re: [SOLUTION] Lost Cities (#51)

Well, it's not brilliant yet, but I've run out of time to keep  
tweaking the risk analysis.  Here's my passible first crack at a  
solution.

Hopefully someone will step in with a player that slaughters him...

James Edward Gray II

#!/usr/local/bin/ruby -w

class RiskPlayer < Player
   def self.card_from_string( card )
     value, land = card[0..-2], card[-1, 1].downcase
     Game::Card.new( value[0] == ?I ? value : value.to_i,
                     Game::LANDS.find { |l| l[0, 1] == land } )
   end

   def initialize
     @piles = Hash.new do |piles, player|
       piles[player] = Hash.new { |pile, land| pile[land] = Array.new }
     end

     @deck_size = 60
     @hand      = nil

     @last_dicard = nil

     @action = nil
   end

   def show( game_data )
     if game_data =~ /^(Your?)(?: opponent)? (play|discard)s? the (\w+)/
       card = self.class.card_from_string($3)
       if $2 == "play"
         if $1 == "You"
           @piles[:me][card.land] << card
         else
           @piles[:them][card.land] << card
         end
       else
         @piles[:discards][card.land] << card
       end

       @last_discard = nil if $1 == "Your"
     end

     if game_data =~ /^\s*Deck:\s+#+\s+\((\d+)\)/
       @deck_size = $1.to_i
     end
     if game_data =~ /^\s*Hand:((?:\s+\w+)+)/
       @hand = $1.strip.split.map { |c| self.class.card_from_string(c) }
     end

     if game_data.include?("Your play?")
       @action = :play_card
     elsif game_data.include?("Draw from?")
       @action = :draw_card
     end
   end

   def move
     send(@action)
   end

   private

   def play_card
     plays, discards = @hand.partition { |card| playable? card }

     if plays.empty?
       discard_card(discards)
     else
       risks   = analyze_risks(plays)
       risk    = risks.max { |a, b| a.last <=> b.last }

       return discard_card(@hand) if risk.last < 0

       land    = risks.max { |a, b| a.last <=> b.last }.first.land
       play    = plays.select { |card| card.land == land }.
                       sort_by { |c| c.value.is_a?(String) ? 0 :  
c.value }.first
       "#{play.value}#{play.land[0, 1]}".sub("nv", "")
     end
   end

   def discard_card( choices )
     discard = choices.sort_by do |card|
       [ playable?(card) ? 1 : 0, playable?(card, :them) ? 1 : 0,
         card.value.is_a?(String) ? 0 : card.value ]
     end.first

     @last_discard = discard
     "d#{discard.value}#{discard.land[0, 1]}".sub("nv", "")
   end

   def draw_card
     want = @piles[:discards].find do |land, cards|
       not @piles[:me][land].empty? and
       cards.last != @last_discard and cards.any? { |card| playable? 
(card) }
     end
     if want
       want.first[0, 1]
     else
       "n"
     end
   end

   def analyze_risks( plays )
     plays.inject(Hash.new) do |risks, card|
       risks[card] = 0

       me_total = ( @piles[:me][card.land] +
                    plays.select { |c| c.land == card.land }
                    ).inject(0) do |total, c|
         if c.value.is_a? String
           total
         else
           total + c.value
         end
       end
       risks[card] += 20 - me_total

       them_total = @piles[:them][card.land].inject(0) do |total, c|
         if c.value.is_a? String
           total
         else
           total + c.value
         end
       end
       high = card.value.is_a?(String) ? 2 : card.value
       risks[card] += ( (high..10).inject { |sum, n| sum + n }
                        - (me_total + them_total) ) / 2

       if @piles[:me][card.land].empty?
         lands_played = @piles[:me].inject(0) do |count, (land, cards)|
           if cards.empty?
             count
           else
             count + 1
           end
         end

         risks[card] -= (lands_played + 1) * 5
       end

       risks
     end
   end

   def playable?( card, who = :me )
     @piles[who][card.land].empty? or
     @piles[who][card.land].last.value.is_a?(String) or
     ( not card.value.is_a?(String) and
       @piles[who][card.land].last.value < card.value )
   end
end

__END__