我已经使用alpha-beta剪枝实现了minimax算法。为了获得最佳移动,我调用了rootAlphaBeta函数中的alpha-beta算法。然而,在rootAlphaBeta函数中,我发现了一些非常奇怪的行为。当我使用4个ply调用rootAlphaBeta函数时,它会进行大约20,000次调用,但是当我直接调用alphaBeta函数时,它只会进行大约2000次调用。我似乎找不到问题所在,因为调用次数应该是相同的。
这两种算法最终找到的移动应该是相同的,对吗?至少移动的得分是相同的,当我在没有rootAlphaBeta的情况下直接调用alphaBeta时,我无法知道alphaBeta选择的移动。
这两种算法最终找到的移动应该是相同的,对吗?至少移动的得分是相同的,当我在没有rootAlphaBeta的情况下直接调用alphaBeta时,我无法知道alphaBeta选择的移动。
def alphaBeta(self, board, rules, alpha, beta, ply, player):
"""Implements a minimax algorithm with alpha-beta pruning."""
if ply == 0:
return self.positionEvaluation(board, rules, player)
move_list = board.generateMoves(rules, player)
for move in move_list:
board.makeMove(move, player)
current_eval = -self.alphaBeta(board, rules, -beta, -alpha, ply - 1,
board.getOtherPlayer(player))
board.unmakeMove(move, player)
if current_eval >= beta:
return beta
if current_eval > alpha:
alpha = current_eval
return alpha
def rootAlphaBeta(self, board, rules, ply, player):
"""Makes a call to the alphaBeta function. Returns the optimal move for a
player at given ply."""
best_move = None
max_eval = float('-infinity')
move_list = board.generateMoves(rules, player)
for move in move_list:
board.makeMove(move, player)
current_eval = -self.alphaBeta(board, rules, float('-infinity'),
float('infinity'), ply - 1,
board.getOtherPlayer(player))
board.unmakeMove(move, player)
if current_eval > max_eval:
max_eval = current_eval
best_move = move
return best_move