task2.py

import math

def print_board(board):
    for row in [board[i*3:(i+1)*3] for i in range(3)]:
        print('| ' + ' | '.join(row) + ' |')
    print()

def minimax(board, depth, is_maximizing, alpha, beta):
    winner = check_winner(board)
    if winner:
        return {'X': -10, 'O': 10, 'Tie': 0}[winner]
    
    if is_maximizing:
        best_score = -math.inf
        for i in range(9):
            if board[i] == ' ':
                board[i] = 'O'
                score = minimax(board, depth + 1, False, alpha, beta)
                board[i] = ' '
                best_score = max(score, best_score)
                alpha = max(alpha, best_score)
                if beta <= alpha:
                    break
        return best_score
    else:
        best_score = math.inf
        for i in range(9):
            if board[i] == ' ':
                board[i] = 'X'
                score = minimax(board, depth + 1, True, alpha, beta)
                board[i] = ' '
                best_score = min(score, best_score)
                beta = min(beta, best_score)
                if beta <= alpha:
                    break
        return best_score

def best_move(board):
    best_score = -math.inf
    move = None
    for i in range(9):
        if board[i] == ' ':
            board[i] = 'O'
            score = minimax(board, 0, False, -math.inf, math.inf)
            board[i] = ' '
            if score > best_score:
                best_score = score
                move = i
    return move

def check_winner(board):
    win_combinations = [(0,1,2), (3,4,5), (6,7,8), (0,3,6), (1,4,7), (2,5,8), (0,4,8), (2,4,6)]
    for combo in win_combinations:
        if board[combo[0]] == board[combo[1]] == board[combo[2]] and board[combo[0]] != ' ':
            return board[combo[0]]
    if ' ' not in board:
        return 'Tie'
    return None

def tic_tac_toe():
    board = [' ' for _ in range(9)]
    print("Welcome to Tic-Tac-Toe!")
    print_board(board)
    
    while True:
        move = int(input("Enter your move (0-8): "))
        if board[move] == ' ':
            board[move] = 'X'
            if check_winner(board):
                print_board(board)
                print("You win!")
                break
            
            ai_move = best_move(board)
            if ai_move is not None:
                board[ai_move] = 'O'
                if check_winner(board):
                    print_board(board)
                    print("AI wins!")
                    break
            
            print_board(board)
            if check_winner(board) == 'Tie':
                print("It's a tie!")
                break

tic_tac_toe()