Implement connect-four

Author: colwem

Gemfile

@@ -2,6 +2,7 @@ source 'http://rubygems.org'
 
 gem 'rspec'
 gem 'pry'
+gem 'debugger'
 
 # Specify your gem's dependencies in percival.gemspec
 gemspec

Rakefile

@@ -35,9 +35,9 @@ task :start do
       c.plugins.plugins = [ClockPlugin,
                            LoggerPlugin,
                            ChannelChangerPlugin,
-                           NameChangerPlugin]
+                           NameChangerPlugin,
+                           ConnectFourPlugin]
     end
   end
-
   bot.start
 end

lib/percival.rb

@@ -5,6 +5,7 @@
 require 'percival/logger'
 require 'percival/channel_changer'
 require 'percival/name_changer'
+require 'percival/connect_four'
 
 PERCIVAL_ROOT = File.dirname(File.dirname(__FILE__))
 

lib/percival/connect_four.rb

@@ -0,0 +1,3 @@
+require 'percival/connect_four/plugin'
+require 'percival/connect_four/connect_four'
+require 'percival/connect_four/board_score'

lib/percival/connect_four/board_score.rb

@@ -0,0 +1,109 @@
+class BoardScore
+
+  WIN_VALUE= 10000
+  DEPTH = 4
+  attr_accessor :score, :win
+  
+  def initialize board
+    @board = board
+    @win = false
+    @score = 0
+    score_board
+  end
+
+  def terminal
+    return true if @win
+  end
+  
+
+  def score_board
+    @board.each_with_index do |column,i|
+      column.each_with_index do |color, j|
+        # up
+        count = counter(color) do |k|
+          @board[i][j+k]
+        end
+        return if won? count, color 
+        @score += color * (count ** 2)
+
+        #up diag
+        count = counter(color) do |k|
+          i+k < @board.size ? @board[i+k][j+k] : nil
+        end
+        return if won? count, color
+        @score += color * (count ** 2)
+
+        #right
+        count = counter(color) do |k|
+          i+k < @board.size ? @board[i+k][j] : nil
+        end
+        return if won? count, color
+
+        @score += color * (count ** 2)
+
+        #down right diag
+        count = counter(color) do |k|
+          j-k >= 0 and i+k < @board.size ? @board[i+k][j-k] : nil
+        end
+        return if won? count, color
+        @score += color * (count ** 2)
+        
+        #down
+        count = counter(color) do |k|
+          j-k >= 0 ? @board[i][j-k] : nil
+        end
+        return if won? count, color
+        @score += color * (count ** 2)
+        
+        #down left diag
+        count = counter(color) do |k|
+          j-k >= 0 and i-k >= 0 ? @board[i-k][j-k] : nil
+        end
+        return if won? count, color
+        @score += color * (count ** 2)
+        
+        # left
+        count = counter(color) do |k|
+          i-k >= 0 ? @board[i-k][j] : nil
+        end
+        return if won? count, color
+        @score += color * (count ** 2)
+
+        #up left diag
+        count = counter(color) do |k|
+          i-k >= 0 ? @board[i-k][j+k] : nil
+        end
+        return if won? count, color
+        @score += color * (count ** 2)
+
+      end
+    end
+  end
+
+  def counter e_color
+    count = 0
+    (0..3).each do |k|
+      color = yield k
+      if color == - e_color
+        count = 0
+        break
+      end
+      count += 1 if color == e_color
+    end
+    count
+  end
+
+  def won? count, color
+    if count == 4
+      @win = color
+      @score = @win * WIN_VALUE
+      return true
+    end
+    false
+  end
+end
+
+
+
+
+

lib/percival/connect_four/connect_four.rb

@@ -0,0 +1,104 @@
+require 'debugger'
+
+class ConnectFour
+  INF = 10000
+  DEPTH = 5
+  attr_accessor :board
+
+  def initialize width, height
+    @width, @height = width, height
+    @my_board = []
+    @your_board = []
+    @width.times { @my_board.push [] }
+  end
+  
+  def your_move move
+    @your_board = new_board @my_board, move, -1
+    rendering =  "
+You dropped a piece at #{move + 1}
+#{board_to_string(@your_board)}"
+
+    bs = BoardScore.new(@your_board)
+    if bs.win
+      return "You win" + rendering
+    end
+    return rendering
+  end
+  
+  def my_move
+    my_move = get_move(@your_board)
+    @my_board = new_board(@your_board, my_move, 1)
+    rendering = "
+I dropped a piece at #{my_move + 1}
+#{board_to_string(@my_board)}"
+
+    bs = BoardScore.new(@my_board)
+    if bs.win
+      return "I win!!\n\n" + rendering
+    end
+    return rendering
+  end
+
+  def you_won
+    "You Won!!! #can't happen"
+  end
+
+  def i_won
+    "I Won!!!"
+  end
+
+  def get_move board
+    idx = 0
+    min = INF
+    (0..board.size - 1).each do |i|
+      nb = new_board board, i, 1
+      val = negamax nb, DEPTH, -INF, INF, -1
+
+      if val < min
+        min = val
+        idx = i
+      end
+    end
+    return idx
+  end
+
+  #negamax alpha beta pruning http://en.wikipedia.org/wiki/Negamax
+  #much better than my mickey mouse implementation of minimax
+  def negamax board, depth, alpha, beta, color
+    bs = BoardScore.new board
+    if depth == 0 or bs.terminal
+      return color * bs.score
+    end
+    (0..(board.size - 1)).each do |i|
+      nb = new_board board, i, color
+      val = - negamax( nb, depth - 1, - beta, - alpha, - color)
+      return val if val >= beta
+      alpha = val if val >= alpha
+    end
+    return alpha
+  end
+
+  def new_board board, move, color
+    nb = Marshal.load(Marshal.dump(board))
+    nb[move].push color
+    nb
+  end
+
+  def board_to_string b
+    l = []
+    (0..@height-1).to_a.reverse.each do |i|
+      e = []
+      (0..@width - 1).each do |j|
+        if b[j][i].nil?
+          e << ' '
+        elsif b[j][i] > 0
+          e << 'X'
+        elsif b[j][i] < 0
+          e << '0'
+        end
+      end
+      l << e.join(' ')
+    end
+    return '|' + l.join("|\n|") + "|\n|1 2 3 4 5 6 7|"
+  end
+end

lib/percival/connect_four/plugin.rb

@@ -0,0 +1,23 @@
+class ConnectFourPlugin
+  include Cinch::Plugin
+
+  def initialize *args
+    super
+    @games = { }
+  end
+  
+  match /cf\s+(\S+)?/, :method => :connect_four
+
+  def connect_four m, command
+    if /new/.match command
+      @games[m.user.name] = ConnectFour.new 7,6
+      m.reply "Awaiting your move sir"
+    elsif /[1-7]/.match command 
+      @games[m.user.name] ||= ConnectFour.new 7,6
+      m.reply @games[m.user.name].your_move(command.to_i - 1)
+      m.reply @games[m.user.name].my_move 
+    else
+      m.reply "command must be in [new|[1-7]]"
+    end
+  end
+end