Class: Tictactoe::MinimaxPlayer

Inherits:
Player
  • Object
show all
Defined in:
lib/tictactoe/minimaxplayer.rb

Instance Attribute Summary

Attributes inherited from Player

#mark

Instance Method Summary collapse

Methods inherited from Player

#finish, #initialize

Constructor Details

This class inherits a constructor from Tictactoe::Player

Instance Method Details

#move(board) ⇒ Object 



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# File 'lib/tictactoe/minimaxplayer.rb', line 8

def move( board )
    # Obtains the available movements
      moves = board.moves

      # For each available movement
      bestValue = -2
      bestMove = ""
      moves.each do |mov|
        newsquares = board.squares.dup
        newboard = Board.new(newsquares)
        newboard[mov] = self.mark
        value = search_best_move(newboard, opponent_mark, 1)
        if (value > bestValue)
bestValue = value
bestMove = mov
        end
      end
      bestMove
end

#opponent_mark ⇒ Object 



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# File 'lib/tictactoe/minimaxplayer.rb', line 65

def opponent_mark
  if (self.mark == "X")
    return "O"
  else
    return "X"
  end
end

#search_best_move(board, mark, level) ⇒ Object 



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# File 'lib/tictactoe/minimaxplayer.rb', line 28

def search_best_move(board, mark, level)
  # Checks if there is a winner  
  return 1 if (board.won? == self.mark)
  return 0 if (board.won? == " ")
  return -1 if (board.won? == opponent_mark)
     
  # Gets the available movements
  moves = board.moves

  # Min level
  if ((level % 2 == 1) && (!board.won?))
    bestValue = 2
    moves.each do |mov|
      newsquares = board.squares.dup
      newboard = Board.new(newsquares)
      newboard[mov] = mark
      value = search_best_move(newboard, self.mark, level + 1)
      if (value < bestValue)
        bestValue = value
      end
    end
  # Max level
  elsif ((level % 2 == 0) && (!board.won?))
    bestValue = -2
    moves.each do |mov|
      newsquares = board.squares.dup
      newboard = Board.new(newsquares)
      newboard[mov] = mark
      value = search_best_move(newboard, opponent_mark, level + 1)
      if (value > bestValue)
        bestValue = value
      end
        end
  end
  bestValue
end