Class: Tictactoe::SmartPlayer

Inherits:
Player
  • Object
show all
Defined in:
lib/tictactoe/smartplayer.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/smartplayer.rb', line 9

def move( board )
  moves = board.moves
  
  # If I have a win, take it.  If he is threatening to win, stop it.
  board.each_row do |row|
    if row.blanks == 1 and (row.xs == 2 or row.os == 2)
      (0..2).each do |e|
        return row.to_board_name(e) if row[e] == " "
      end
    end
  end

  # Take the center if open.
  return "b2" if moves.include? "b2"

  # Defend opposite corners.
  if board[0] != @mark and board[0] != " " and board[8] == " "
    return "c3"
  elsif board[8] != @mark and board[8] != " " and board[0] == " "
    return "a1"
  elsif board[2] != @mark and board[2] != " " and board[6] == " "
    return "c1"
  elsif board[6] != @mark and board[6] != " " and board[2] == " "
    return "a3"
  end
  
  # Defend against the special case XOX on a diagonal.
  if board.xs == 2 and board.os == 1 and board[4] == "O" and
     (board[0] == "X" and board[8] == "X") or
     (board[2] == "X" and board[6] == "X")
    return %w{a2 b1 b3 c2}[rand(4)]
  end
  
  # Or make a random move.
  moves[rand(moves.size)]
end