下面是一段基于 **极大极小值算法** 的 Python 实现代码，用于玩井字棋游戏 (Tic-Tac-Toe)： ```python import math def print_board(board): for row in board: print(" ".join(row)) print() def evaluate(board): # 检查行、列和对角线是否获胜 for row in board: if row.count('X') == 3: return 10 elif row.count('O') == 3: return -10 for col in range(3): if board[0][col] == board[1][col] == board[2][col]: if board[0][col] == 'X': return 10 elif board[0][col] == 'O': return -10 if board[0][0] == board[1][1] == board[2][2]: if board[0][0] == 'X': return 10 elif board[0][0] == 'O': return -10 if board[0][2] == board[1][1] == board[2][0]: if board[0][2] == 'X': return 10 elif board[0][2] == 'O': return -10 return 0 def is_moves_left(board): for row in board: if '_' in row: return True return False def minimax(board, depth, is_max): score = evaluate(board) if score == 10 or score == -10: return score if not is_moves_left(board): return 0 if is_max: best = -math.inf for i in range(3): for j in range(3): if board[i][j] == '_': board[i][j] = 'X' best = max(best, minimax(board, depth + 1, not is_max)) board[i][j] = '_' return best else: best = math.inf for i in range(3): for j in range(3): if board[i][j] == '_': board[i][j] = 'O' best = min(best, minimax(board, depth + 1, not is_max)) board[i][j] = '_' return best def find_best_move(board): best_val = -math.inf move = (-1, -1) for i in range(3): for j in range(3): if board[i][j] == '_': board[i][j] = 'X' val = minimax(board, 0, False) board[i][j] = '_' if val > best_val: best_val = val move = (i, j) return move # 示例主程序 if __name__ == "__main__": board = [ ['_', '_', '_'], ['_', '_', '_'], ['_', '_', '_'] ] print("初始棋盘状态:") print_board(board) best_move = find_best_move(board) print(f"最佳移动位置: 行 {best_move[0]+1}, 列 {best_move[1]+1}") ``` ### 程序说明： 1. 极大极小搜索的核心思想是通过递归评估每个可能的走法，并选择对自己最有利而对对手不利的动作。 2. `evaluate()` 函数负责判断当前局面的状态并返回分数（胜利得正分，失败负分）。 3. `minimax()` 函数实现了核心的递归部分，`is_max` 参数控制何时取最大值或最小值。 --- ####