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 



8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
 
# 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 



65
66
67
68
69
70
71
 
# 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 



28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
 
# 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