基于α-β剪枝算法的五子棋游戏代码

以下是一个基于α-β剪枝算法的五子棋游戏代码示例（Python实现）：

import random

# 定义棋盘的大小
BOARD_SIZE = 15

# 定义棋子的类型
EMPTY = 0
BLACK = 1
WHITE = 2

# 定义棋子在棋盘上的表示方式
PIECE_STR = ['.', 'X', 'O']

# 定义棋盘
board = [[EMPTY for x in range(BOARD_SIZE)] for y in range(BOARD_SIZE)]

# 定义α-β剪枝算法中的最大深度
MAX_DEPTH = 3

# 定义评估函数中的权重
SCORE_WEIGHTS = [0, 1, 10, 100, 1000, 10000]


def print_board():
    """打印棋盘"""
    print(" ", end="")
    for i in range(BOARD_SIZE):
        print("{:2d}".format(i), end="")
    print()
    for i in range(BOARD_SIZE):
        print("{:2d}".format(i), end="")
        for j in range(BOARD_SIZE):
            print(" " + PIECE_STR[board[i][j]], end="")
        print()


def get_winner():
    """获取胜者"""
    for x in range(BOARD_SIZE):
        for y in range(BOARD_SIZE):
            if board[x][y] == EMPTY:
                continue
            if y + 4 < BOARD_SIZE and \
                    board[x][y] == board[x][y + 1] == board[x][y + 2] == board[x][y + 3] == board[x][y + 4]:
                return board[x][y]
            if x + 4 < BOARD_SIZE and \
                    board[x][y] == board[x + 1][y] == board[x + 2][y] == board[x + 3][y] == board[x + 4][y]:
                return board[x][y]
            if x + 4 < BOARD_SIZE and y + 4 < BOARD_SIZE and \
                    board[x][y] == board[x + 1][y + 1] == board[x + 2][y + 2] == board[x + 3][y + 3] == board[x + 4][y + 4]:
                return board[x][y]
            if x + 4 < BOARD_SIZE and y - 4 >= 0 and \
                    board[x][y] == board[x + 1][y - 1] == board[x + 2][y - 2] == board[x + 3][y - 3] == board[x + 4][y - 4]:
                return board[x][y]
    return EMPTY


def get_score(piece_type):
    """计算当前棋盘的得分"""
    score = 0
    for x in range(BOARD_SIZE):
        for y in range(BOARD_SIZE):
            if board[x][y] != piece_type:
                continue
            for direction_x, direction_y in [(1, 0), (0, 1), (1, 1), (1, -1)]:
                cnt = 1
                for i in range(1, 5):
                    new_x, new_y = x + i * direction_x, y + i * direction_y
                    if new_x >= BOARD_SIZE or new_y >= BOARD_SIZE or board[new_x][new_y] != piece_type:
                        break
                    cnt += 1
                score += SCORE_WEIGHTS[cnt]
    return score


def alpha_beta_pruning(piece_type, depth, alpha, beta):
    """α-β剪枝算法"""
    winner = get_winner()
    if winner == piece_type:
        return 1000000
    if winner != EMPTY:
        return -1000000
    if depth == MAX_DEPTH:
        return get_score(piece_type) - get_score(3 - piece_type)

    best_score = -float("inf") if piece_type == BLACK else float("inf")
    for x in range(BOARD_SIZE):
        for y in range(BOARD_SIZE):
            if board[x][y] != EMPTY:
                continue
            board[x][y] = piece_type
            score = alpha_beta_pruning(3 - piece_type, depth + 1, alpha, beta)
            board[x][y] = EMPTY
            if piece_type == BLACK:
                best_score = max(best_score, score)
                alpha = max(alpha, score)
            else:
                best_score = min(best_score, score)
                beta = min(beta, score)
            if alpha >= beta:
                return best_score

    return best_score


def ai_make_move():
    """AI下棋"""
    best_moves = []
    best_score = -float("inf")
    for x in range(BOARD_SIZE):
        for y in range(BOARD_SIZE):
            if board[x][y] != EMPTY:
                continue
            board[x][y] = BLACK
            score = alpha_beta_pruning(WHITE, 1, -float("inf"), float("inf"))
            board[x][y] = EMPTY
            if score > best_score:
                best_score = score
                best_moves = [(x, y)]
            elif score == best_score:
                best_moves.append((x, y))
    return random.choice(best_moves)


if __name__ == "__main__":
    while True:
        print_board()
        winner = get_winner()
        if winner != EMPTY:
            print("游戏结束，胜者是：", PIECE_STR[winner])
            break
        x, y = map(int, input("请下棋（x y）：").split())
        if board[x][y] != EMPTY:
            print("非法落子，请重新输入")
            continue
        board[x][y] = WHITE
        x, y = ai_make_move()
        print("AI下棋：", x, y)
        board[x][y] = BLACK

这个代码实现了一个简单的五子棋游戏，使用了α-β剪枝算法来实现AI下棋。其中，`get_winner`函数用来判断胜负，`get_score`函数用来评估当前棋盘的得分，`alpha_beta_pruning`函数用来执行α-β剪枝算法，`ai_make_move`函数用来让AI下棋。