minimax 跳棋算法用完移动

Question

我正在为西洋跳棋软件开发一个 minimax 算法，我的算法崩溃了，因为它一直说没有可用的动作，而实际上有。手动播放时不会发生这种情况。

我的算法如下：

def _minimax(self, board_state : Board, depth : int, max_player : bool, game : Game):
        if depth == 0 or game.end_game:
            return board_state._evaluate(), board_state

        best_move = None
        if max_player: #if AI
            best = -math.inf
            all_moves = self.get_all_moves(board_state, "B", game) #get simulated moves
            for piece, move, new_board in all_moves:
                eval, _ = self._minimax(new_board, depth - 1, False, game)
                if eval > best:
                    best = eval
                    best_move = (piece, move, new_board)

        else: #if random or human
            best = math.inf
            all_moves = self.get_all_moves(board_state, "R", game)
            for piece, move, new_board in all_moves:
                eval, _ = self._minimax(new_board, depth - 1, True, game)
                if eval < best:
                    best = eval
                    best_move = (piece, move, new_board)

        return best, best_move

我对

simulate_move

方法的实现如下：

def simulate_move(self, piece, move, game):

        game.move(piece, move)
        return game.board 

我对

get_all_moves

方法的实现如下：

def get_all_moves(self, board, color, game):
        #get all possible moves that we can make from a board
        moves = []

        all_moves = game.player_all_moves(board, color)

        for _,move,piece in all_moves:
            #make a copy of the current board state
            temp_game = deepcopy(game)
            new_board = self.simulate_move(piece, move, temp_game)
            moves.append((piece, move, new_board))

        return moves

suggest_move

方法内部调用了minimax算法，即：

def suggest_move(self):
 

        eval, best_move = self._minimax(self._board, 2, True, self._game)


        piece, sug_move, new_board = best_move

        return piece, sug_move, new_board

最后，这是我模拟游戏的方式（这是在一个更大的函数中，不需要发布整个函数）：

piece, move, new_board = current.suggest_move()
game.move(piece, move)
game.board = new_board

**编辑： 错误回溯是：

Traceback (most recent call last):
  File "bots.py", line 289, in <module>
    cmd()
  File "/usr/local/lib/python3.8/dist-packages/click/core.py", line 1137, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/click/core.py", line 1062, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.8/dist-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.8/dist-packages/click/core.py", line 763, in invoke
    return __callback(*args, **kwargs)
  File "bots.py", line 213, in cmd
    simulate(game, num_games, bots)
  File "bots.py", line 184, in simulate
    piece, move, new_game = current.suggest_move()
  File "bots.py", line 68, in suggest_move
    piece, sug_move, new_game = best_move
TypeError: cannot unpack non-iterable NoneType object

请让我知道我的代码可能有什么问题！谢谢。

我尝试过手动测试，在我的模拟中模拟西洋跳棋游戏的开始，看看是否会出现同样的错误。手动播放时我没有收到错误消息——我可以移动到棋盘上的可用空间。同样奇怪的是，当我打印游戏中每一轮的可用动作时，它说代码错误时没有动作。