CODEWITHSUNDEEP
pythonartificial-intelligencetic-tac-toeminimax
Chinesh
Chinesh

Reputation: 135

tic tac toe and minimax algorithm

I am trying to make tic tac toe using minimax algorithm. I am referring to the following code. But I am not understanding the use of [0]. Please explain the following line:

value = self.move(x,y).minimax(not player)[0]

taking the reference of the code given below. And also tell the use of returning "None" along with +1 or -1 or 0. Please do not negative vote my question or I will be blocked.

def minimax(self, player):
    if self.won():
      if player:
        return (-1,None)
      else:
        return (+1,None)
    elif self.tied():
      return (0,None)
    elif player:
      best = -2,0
      for x,y in self.fields:
        if self.fields[x,y]==self.empty:
          value = self.move(x,y).minimax(not player)[0]
          if value>best[0]:
            best = (value,(x,y))
      return best
    else:
      best = (+2,None)
      for x,y in self.fields:
        if self.fields[x,y]==self.empty:
          value = self.move(x,y).minimax(not player)[0]
          if value<best[0]:
            best = (value,(x,y))
      return best

Upvotes: 1

Views: 242

Answers (2)

Scott Hunter
Scott Hunter

Reputation: 49920

minimax returns a tuple; the statement in question is calling minimax, taking the first element of the returned tuple (the [0] bit) and assigning that to best.

Upvotes: 2

L3viathan
L3viathan

Reputation: 27333

But I am not understanding the use of [0]

The function returns a tuple of (value,(x,y)), so accessing the 0th element of that will give you value.

The function returns None in the value when the game is over, since no new move is made. The value will be who won (with 0 meaning they tied).

Upvotes: 1

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