所以，我正在编写一个非常简单的井字游戏程序，使用Alpha-Beta剪枝来搜索对抗玩家的下一步，但每次我想运行它时都会遇到问题。我尝试了所有能想到的方法来解决它，甚至还制作了一个Java版本的逐行等效逻辑，运行得非常完美，但Python版本就是不工作。
这是我的代码：
#encoding: UTF-8#Andres de Lago Gomez#A01371779from random import randintfrom utils import *def getEnemy(who): return 1 if who==2 else 2def getLetter(who): return "X" if who==1 else "O"class TicTacToe: winningCombos =[[0, 1, 2], [3, 4, 5], [6, 7, 8], [0, 3, 6], [1, 4, 7], [2, 5, 8], [0, 4, 8], [2, 4, 6]] board = [0 for i in range(9)] player = 1 cpu = 2 def __init__(self): pass def makeMove(self, who, pos): self.board[pos] = who def setCpu(self, who): self.player = who self.cpu = getEnemy(who) def availableMoves(self): return [i for i in range(9) if self.board[i]==0] def isOver(self): if 0 not in self.board: return True if self.Winner(): return True return False def Winner(self): for i in [1,2]: positions = self.getSquares(i) for combo in self.winningCombos: win = True for pos in combo: if pos not in positions: win = False if win: return i return False def getSquares(self, player): return [i for i in range(9) if self.board[i]==player] def alphaBeta(self, player, alpha, beta): if self.isOver(): return self.evaluateNode() for move in self.availableMoves(): self.makeMove(move, player) value = self.alphaBeta(getEnemy(player),alpha,beta) self.makeMove(move, 0) if player == self.cpu: if alpha < value: alpha = value if alpha >=beta: return beta else: if beta > value: beta = value if beta <= alpha: return alpha return alpha if player==self.cpu else beta def evaluateNode(self): tmp = self.Winner() if tmp==self.cpu: return 1 elif tmp==self.player: return -1 else: return 0 def getNextMove(self, player): test = -5 possibleMoves = [] for move in self.availableMoves(): self.makeMove(player, move) value = self.alphaBeta(getEnemy(player), -5, 5) self.makeMove(0, move) if value>test: test = value possibleMoves = [move] elif value == test: possibleMoves.append(move) return possibleMoves[randint(0, len(possibleMoves)-1)]class Tile(pygame.sprite.Sprite): def __init__(self, rect, screen, player="X"): pygame.sprite.Sprite.__init__(self) self.rect = rect self.images = [load_png(get_path()+"\\data\\TicTacToe\\"+player+"Tile\\{0:0>2d}.png".format(x)) for x in range(21)] clock = pygame.time.Clock() for i in range(21): self.image = self.images[i] screen.blit(self.image, self.rect) pygame.display.update(self.rect) clock.tick(80)class GUI: def __init__(self): pygame.init() self.screen = pygame.display.set_mode([100,100]) self.dir = get_path() #get background self.background = pygame.image.load(self.dir+"\\data\\TicTacToe\\Background.png") self.background.convert() self.tiles = pygame.sprite.Group() #blit to screen self.screen = pygame.display.set_mode(self.background.get_size()) self.screen.blit(self.background,(0,0)) pygame.display.update() #create tiles self.places = [pygame.Rect((15+165*x, 110+165*y), (150,150) )for x in range(3) for y in range (3)] #create game self.board = TicTacToe() done = False goFirstI = load_png(get_path()+"\\data\\TicTacToe\\GoFirst.png") goFirstR = pygame.Rect((0,0), (400,200)) goFirstR.center = self.places[4].center self.screen.blit(goFirstI,goFirstR) pygame.display.update(goFirstR) yesR = pygame.Rect((97,382),(115,45)) noR = pygame.Rect((297,382),(115,45)) while not done: for event in pygame.event.get(): if event.type == pygame.MOUSEBUTTONUP: if event.button == 1: if yesR.collidepoint(event.pos): done = True self.board.setCpu(1) elif noR.collidepoint(event.pos): done = True self.board.setCpu(2) self.screen.blit(self.background,(0,0)) pygame.display.update(goFirstR) #start clock clock = pygame.time.Clock() done = False turn = 1 bdown = 0 while not done: for event in pygame.event.get(): if event.type == pygame.QUIT: done = True elif event.type == pygame.KEYDOWN: if event.key == pygame.K_ESCAPE: pass #pause menu? elif event.type == pygame.MOUSEBUTTONUP: if event.button == 1: bdown = event if turn == self.board.player: if bdown != 0: index = 0 for rect in self.places: if rect.collidepoint(bdown.pos): moves = self.board.availableMoves() if index in moves: self.board.makeMove(turn, index) self.tiles.add(Tile(rect, self.screen, getLetter(self.board.player))) turn = getEnemy(turn) index += 1 else: pos = self.board.getNextMove(self.board.cpu) self.board.makeMove(turn, pos) self.tiles.add(Tile(self.tiles[pos], self.screen, getLetter(self.board.cpu))) clock.tick(60)a = GUI()我得到的错误是： RuntimeError: maximum recursion depth exceeded
我非常希望能了解是什么导致了这个错误。
回答：
Python和Java处理递归的方式不同。Python的堆栈框架较大，因此对递归次数有严格的限制，即你的代码可以调用自身的次数，在崩溃并抛出该错误之前。在你的代码中，这是你的 def alphaBeta(self, player, alpha, beta) 方法，它本身调用了： value = self.alphaBeta(getEnemy(player),alpha,beta)
在Java中，情况略有不同，因为Java进行了更多的优化。这意味着在得到Java堆栈溢出错误之前，你可以有更多的递归调用。
你最好的选择是将你的代码从递归函数改为迭代函数。即，修改你的alphaBeta方法，使其不调用自身，而是使用for或while循环来完成相同的事情
