[Tutor] Reversi Game Logic

[Mark Lawrence]

On 20/03/2015 00:50, niyanaxx95 at gmail.com wrote:

 From just a quick glance seeing it's 3 in the morning here.

> I am having trouble with a function in my reversi logic code. The function is the isLegalMove I am asked to "Return a Boolean indicating if the current player can place their chip in the square at position (row, col). Both row and col must be valid indices​." So I came up with my code below, however a move I make in the game says Error: not a legal move. Please help!
>
> Code:
>
> from ezarrays import Array2D
>
> # Values representing the color of the chips on the board.
> EMPTY = 0
> BLACK = 1
> WHITE = 2
>
>
> class ReversiGameLogic :
>
>    # Creates an instance of Reversi game logic with the board correctly
>    # initialized and the current player set to black.
>    def __init__(self) :
>       # Use a 2-D array to represent the board.
>      self._gameBoard = Array2D(8, 8)
>      self._gameBoard.clear(EMPTY)
>
>       # Set the initial configuration of the board.
>      self._gameBoard[4,3] = BLACK
>      self._gameBoard[3,4] = BLACK
>      self._gameBoard[3,3] = WHITE
>      self._gameBoard[4,4] = WHITE
>
>       # Maintain the number of the current player.
>      self._currentPlayer = BLACK
>
>       # Keep track of the number of each players chips.
>      self._numBlackChips = 2
>      self._numWhiteChips = 2
>
>       # A flag that is set when the game is over. That is, when there are
>       # no empty squares on the board or neither player can make a move.
>      self._gameOver = False
>
>    # Returns a boolean indicating whether the game is over.
>    def isOver(self) :
>      isOver = 0
>      for i in range(8) :
>        for j in range(8) :
>          if self._gameBoard[i, j] != 0 :
>            isOver + 1

The above line does nothing.

>      if isOver == 64 :
>          self._gameOver = True
>          return True
>      else:
>          return False
>
>    # Returns the player number of the current player.
>    def whoseTurn(self) :
>      if self._currentPlayer == 1:
>        return 1
>      else:
>        self._curentPlayer == 2

The above line has two errors.

>      return 2
>
>    # Returns the number of chips on the board for the given player.
>    def numChips(self, player) :
>      chipCounter = 0
>      if player == 1 :
>        for i in range(8) :
>          for j in range(8) :
>            if self._gameBoard[i, j] == BLACK :
>              chipCounter = chipCounter + 1
>      else :
>        for i in range(8) :
>          for j in range(8) :
>            if self._gameBoard[i, j] == WHITE :
>              chipCounter = chipCounter + 1
>      return chipCounter
>

You can greatly simplify the above function - I'll let you think about it :)

>    # Returns the number of open squares on the board.
>    def numOpenSquares(self) :
>      numOpenSquares = 0
>      for i in range(8) :
>        for j in range(8) :
>          if self._gameBoard[i, j] == EMPTY :
>            numOpenSquares =  numOpenSquares + 1
>      return numOpenSquares
>
>    # Returns the player number of the winner or 0 if it's a draw.
>    def getWinner( self ):
>      player1 = 0
>      player2 = 0
>      if self._gameOver is True :
>        for i in range(8) :
>          for j in range(8) :
>            if self._gameBoard[i, j] == BLACK :
>              player1 = player1 + 1
>            else :
>              player2 = player2 + 1
>        if player1 > player2 :
>          return 1
>        if player2 > player1 :
>          return 2
>        else:
>          return 0
>
>    # Returns the
>    def isLegalMove( self, row, col):
>      if row < 8 and col < 8:

In Python the above line can be written.

if row < 8 > col:

>        if self._gameBoard[row,col] != EMPTY:
>          return True
>      else:
>        return False
>
>     # Returns the player number whose chip occupies the given square.
>    def occupiedBy(self, row, col):
>      if self._gameBoard[row, col] == BLACK :
>        return 1
>      if self._gameBoard[row, col] == WHITE :
>        return 2
>      else:
>        return 0
>
>    # Performs an actual move in the game. That is the current player places
>    # one of his chips in the square at position (row, col).
>    def makeMove( row, col ):
>      if isALineOfAttack(row, col, 1, 1) is True :
>        if self._currentPlayer == 1 :
>          self._gameBoard[row, col] = BLACK
>        else :
>          self._gameBoard[row, col] = WHITE
>
>     # Helper method that returns a Boolean indicating if there is a line of
>     # attack from cell (row, col) in the direction offset given by rowInc
>     # and colInc. The direction offsets should be, 0, 1, or -1.
>    def _isALineOfAttack(self, row, col, rowInc, colInc) :
>      row += rowInc
>      col += colInc
>       # The next cell in the line must contain the opponents chip.
>      if self.occupiedBy(row, col) == self._currentPlayer :
>        return False
>
>       # Traverse along the line and determine if it's a line of attack.
>      while row >= 0 and col >= 0 and row < 8 and col < 8 :

Again Python comparisons don't need to be written like this.

>        if self.occupiedBy(row, col) == self._currentPlayer :
>          return True
>        elif self.occupiedBy(row, col) == EMPTY :
>          return False
>        else :
>          row += rowInc
>          col += colInc
>          if row < 0 or row > 7 or col < 0 or col > 7 :
>                return False
>      return False



-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence