类中的递归，Python

Question

我正在尝试创建一个类，该类可以从 Game Tic-Tac-Toe 中为棋盘生成决策树。我正在使用帖子Tic-Tac-Toe: How to populate decision tree? 上用户“ssoler”的评论作为课程的基础，但我认为课程没有工作。一方面，我看不到所有输出，因为使用“...”将它们缩写为空闲。我过去对类和递归的使用也很差。我的目标是将 Minimax 算法和 alpha-beta 修剪应用于类输出的树。

win_comb=((0,1,2),(3,4,5),(6,7,8),(6,3,0),(7,4,1),(8,5,2),(6,4,2),(8,4,0))
Board = [1, 2, 3, 4, 5, 6, 7, 8, 9]
whose_move = 1
child_nodes = []

class Node():
    def __init__(self,Board,win_comb,whose_move, child_nodes):
        self.c_g_s = Board
        self.node = None
        self.new_node = None
        self.child_nodes = child_nodes
        self.win_comb = win_comb
        self.w_m = whose_move

    def create_tree(self):
        for index,each in enumerate(self.c_g_s):
            if each == index + 1:
                self.new_node = self.c_g_s
                if self.w_m == 1:
                    self.new_node[index] = "X"
                    self.w_m = 0
                else:
                    self.new_node[index] = "O"
                    self.w_m = 1
                self.new_node = tuple(self.new_node)
                if self.available_moves():
                    self.new_node = self.c_g_s
                    self.child_nodes.append(self.create_tree())
                else:
                    child_nodes.append(self.new_node)
        if self.child_nodes:
            return [self.node,self.child_nodes]
        return

    def available_moves(self):
        for index, each in enumerate(self.c_g_s):
            if index + 1 == each:
                return False
        return True

n = Node(Board,win_comb,whose_move,child_nodes)


print(n.create_tree())

Answer 1

我猜你的程序的这种简化会产生你想要的东西，所有可能的板都是一棵树。现在，您可以使用获胜组合列表来显着修剪生成的分支：

winning_combinations = ((0,1,2), (3,4,5), (6,7,8), (6,3,0), (7,4,1), (8,5,2), (6,4,2), (8,4,0))
board = [1, 2, 3, 4, 5, 6, 7, 8, 9]
whose_move = 1

class Node():
    def __init__(self, board, whose_move):
        self.board = board
        self.whose_move = whose_move

    def create_tree(self, board=None, whose_move=None):

        if board is None:
            board = self.board
        if whose_move is None:
            whose_move = self.whose_move

        child_nodes = []

        for index, square in enumerate(board):
            if square == index + 1:  # if square not taken
                new_board = list(board)  # make a shallow copy

                if whose_move == 1:
                    new_board[index] = "X"
                    whose_move = 0
                else:
                    new_board[index] = "O"
                    whose_move = 1

                if self.available_moves(new_board):
                    child_nodes.append(self.create_tree(new_board, whose_move))
                else:
                    child_nodes.append(new_board)
        return child_nodes

    def available_moves(self, board):
        for index, square in enumerate(board):
            if square == index + 1:  # if square not taken
                return True
        return False

node = Node(board, whose_move)

print(node.create_tree())

关键是不要在你的对象中存储你想要临时变异以查看可能发生什么的东西（例如董事会以及轮到谁了）——制作那些局部变量。此外，您的 available_moves() 方法将 True 和 False 颠倒了。