Minimax Ruby

gistfile1.rb

    def get_minimax_move(board,max_symbol,min_symbol)
      set_min_and_max_players(max_symbol, min_symbol)
      best_score_for_max = @max.starting_score
      alpha = -100
      beta = 100
      depth = 0
      
      board.available_spaces.each do |space|
        test_board = copy(board)
        test_board.place_move(@max.symbol, space)
        new_score = minimax_score(test_board, opponent_of(@max), alpha, beta, depth + 1)
        if new_score > best_score_for_max
          best_score_for_max = new_score
          @possible_moves = []
          @possible_moves << space
        elsif new_score == best_score_for_max
          @possible_moves << space
        end
      end
      return chosen_move
    end

    def minimax_score(board, player, alpha, beta, depth)
      score = game_value(board, depth)
      return score unless score == -1
      best_score = player.starting_score
    
      board.available_spaces.each do |space|
        test_board = copy(board)
        test_board.place_move(player.symbol, space)
        new_score = minimax_score(test_board, opponent_of(player), alpha, beta, depth + 1)
        best_score = player.compare(best_score, new_score)      
        is_max?(player) ? alpha = best_score : beta = best_score
        break if alpha >= beta
      end
    
      return best_score
    end