Class: TTT::AIMedium

Inherits:
AI show all
Defined in:
lib/ttt/ai_medium.rb,
lib/ttt/ai_medium_back.rb

Instance Attribute Summary collapse

Attributes inherited from AI

#board

Attributes inherited from Player

#side

Instance Method Summary collapse

Methods inherited from AI

#available_moves, #no_gui?, #opposite_side, #prompt, #undo_move

Methods included from Minimax

#alpha_beta_swapped?, #base_case_satisfied?, #eval_score, #gen_score_game_tree, #mark_curr_player_side, #winning_score

Methods inherited from Player

#==, #initialize

Constructor Details

This class inherits a constructor from TTT::Player

Instance Attribute Details

#best ⇒ Object

Returns the value of attribute best.



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# File 'lib/ttt/ai_medium_back.rb', line 4

def best
  @best
end

#max_ply ⇒ Object

Returns the value of attribute max_ply.



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# File 'lib/ttt/ai_medium_back.rb', line 4

def max_ply
  @max_ply
end

Instance Method Details

#max_min_swapped?(max, min) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ttt/ai_medium_back.rb', line 54

def max_min_swapped?(max, min)
  max >= min
end

#minimax(max_player = true, ply = 0, min_score = 1000, max_score = -1000)) ⇒ Object 



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# File 'lib/ttt/ai_medium_back.rb', line 15

def minimax(max_player = true, ply = 0, min_score = 1000, max_score = -1000)
  if board.winner?
    return(max_player ? (-1000 + ply) : (1000 - ply))
  elsif board.draw_game?
    return 0
  end

  if ply >= max_ply
    return(max_player ? (max_score) : (min_score))
  end

  best_move = 0
  score = (max_player ? max_score : min_score )
  available_moves.each do |index|
    board[][index] = ( max_player ? side : opposite_side(side) )
    score          = minimax(!max_player, ply + 1, min_score, max_score)
    undo_move(index)
    if max_player && score > max_score
      max_score  = score
      best_move  = index
    elsif !max_player && score < min_score
      min_score  = score
    end
    break if max_min_swapped?(max_score, min_score)
  end

  return( ply == 0 ? best_move : ( max_player ? max_score : min_score ) )
end

#move(options) ⇒ Object 



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# File 'lib/ttt/ai_medium.rb', line 5

def move(options)
  super
  self.max_ply = set_max_ply(available_moves.length)
  minimax
end

#set_max_ply(moves) ⇒ Object 



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# File 'lib/ttt/ai_medium.rb', line 11

def set_max_ply(moves)
  if moves > 15
   return 3
  elsif moves > 5
   return 5
  else
   return 7
  end
end