我一直在尝试为一个简单的井字游戏实现极小值,但尽管它确实运行,但我无法获得正确的结果。该函数假定AI正在以“ O”播放,而玩家正在以“ X”播放。
import itertools
class Board:
def __init__(self):
self.grid = {}
def get_symbol(self, move):
return self.grid.get(move)
def set_symbol(self, move, symbol):
self.grid[move] = symbol
def clear_symbol(self, move):
self.grid.pop(move)
def has_winner(self):
return self.is_winner('X') or self.is_winner('O')
def is_winner(self, symbol):
wins = [[(0, 0), (1, 0), (2, 0)],
[(0, 1), (1, 1), (2, 1)],
[(0, 2), (1, 2), (2, 2)],
[(0, 0), (0, 1), (0, 2)],
[(1, 0), (1, 1), (1, 2)],
[(2, 0), (2, 1), (2, 2)],
[(0, 0), (1, 1), (2, 2)],
[(0, 2), (1, 1), (2, 0)]]
for win in wins:
if all(self.get_symbol(e) == symbol for e in win):
return True
return False
def is_full(self):
return all(self.get_symbol(tuple(e)) is not None for e in itertools.product(range(3), repeat=2))
def get_moves(self):
return [move for move in itertools.product(range(3), repeat=2) if move not in self.grid.keys()]
def get_heuristic(self):
if self.is_winner('X'):
return -1
if self.is_winner('O'):
return 1
return 0
def get_enemy(symbol):
if symbol == 'O':
return 'X'
return 'O'
def is_terminal(board):
return board.has_winner() or board.is_full()
def minimax(board, depth, piece):
if depth == 0 or is_terminal(board):
return board.get_heuristic()
if piece == 'O':
value = float('-inf')
for move in board.get_moves():
board.set_symbol(move, piece)
value = max(value, minimax(board, depth-1, get_enemy(piece)))
board.clear_symbol(move)
return value
else:
value = float('inf')
for move in board.get_moves():
board.set_symbol(move, piece)
value = min(value, minimax(board, depth-1, get_enemy(piece)))
board.clear_symbol(move)
return value
def main():
board = Board()
board.set_symbol((0, 0), 'X')
board.set_symbol((0, 1), 'O')
board.set_symbol((1, 0), 'X')
moves = board.get_moves()
scores = []
for move in moves:
board.set_symbol(move, 'O')
scores.append(minimax(board, 100, 'O'))
board.clear_symbol(move)
m = max(scores)
for i, e in enumerate(moves):
if scores[i] == m:
print(e)
if __name__ == '__main__':
main()
此应该打印'(2,0)',因为任何其他位置都将导致'X'在下一回合获胜,但是根据所处的深度,它会打印6个可能结果的各个子集达到最大我曾尝试使用'X'和'O'作为minimax函数的初始参数,但均未给出正确的结果。怎么了?
我相信错误在于您的Minimax函数。您在函数的参数中调用该段,但同时为maximizingPlayer
和minimizingPlayer
递归调用了该段(对于O
和X
段均意味着)。
我相信这是更新的功能,至少解决了一个问题:
def minimax(board, depth, piece):
if depth == 0 or is_terminal(board):
return board.get_heuristic() #else return a value for the board
if piece == 'O':
value = float('-inf')
for move in board.get_moves():
board.set_symbol(move, 'X') #'X'. Drop an X piece and see where they score their highest move so that O can maximize it
value = max(value, minimax(board, depth-1, get_enemy(piece)))
board.clear_symbol(move)
return value
else:
value = float('inf')
for move in board.get_moves():
board.set_symbol(move, 'O') #'O' Drop an O piece and see where they score their highest move so that X can minimize it
value = min(value, minimax(board, depth-1, get_enemy(piece)))
board.clear_symbol(move)
return value