import pygame
    import random   
    # 初始化Pygame
    pygame.init()   
    # 游戏窗口设置
    WIDTH, HEIGHT = 800, 600
    WIN = pygame.display.set_mode((WIDTH, HEIGHT))
    pygame.display.set_caption("贪吃蛇")
    # 颜色定义
    BLACK = (0, 0, 0)
    WHITE = (255, 255, 255)
    RED = (255, 0, 0)
    GREEN = (0, 255, 0)

    # 蛇和食物的初始设置
    SNAKE_SIZE = 20
    snake = [(WIDTH//2, HEIGHT//2)]
    snake_direction = (0, 0)
    food = (random.randint(0, (WIDTH-SNAKE_SIZE)//SNAKE_SIZE)*SNAKE_SIZE,
    random.randint(0, (HEIGHT-SNAKE_SIZE)//SNAKE_SIZE)*SNAKE_SIZE)
    # 游戏主循环
    clock = pygame.time.Clock()
    running = True
    game_over = False
    while running:
      clock.tick(30)  # 控制游戏速度（每秒帧数）
      # 处理事件（如按键）
      for event in pygame.event.get():
        if event.type == pygame.QUIT:
          running = False
        elif event.type == pygame.KEYDOWN and not game_over:
          if event.key == pygame.K_UP and snake_direction != (0, SNAKE_SIZE):
            snake_direction = (0, -SNAKE_SIZE)
            elif event.key == pygame.K_DOWN and snake_direction != (0, -SNAKE_SIZE):
            snake_direction = (0, SNAKE_SIZE)
        elif event.key == pygame.K_LEFT and snake_direction != (SNAKE_SIZE, 0):
            snake_direction = (-SNAKE_SIZE, 0)
        elif event.key == pygame.K_RIGHT and snake_direction != (-SNAKE_SIZE, 0):
            snake_direction = (SNAKE_SIZE, 0)

if not game_over:
    # 移动蛇头
    new_head = (snake + snake_direction, snake + snake_direction)
    snake.insert(0, new_head)

    # 检测是否吃到食物
    if snake == food:
        food = (random.randint(0, (WIDTH-SNAKE_SIZE)//SNAKE_SIZE)*SNAKE_SIZE,
                random.randint(0, (HEIGHT-SNAKE_SIZE)//SNAKE_SIZE)*SNAKE_SIZE)
    else:
        snake.pop()

    # 碰撞检测
    if (snake < 0 or snake >= WIDTH or
        snake < 0 or snake >= HEIGHT or
        snake in snake[1:]):
        game_over = True

# 绘制画面
WIN.fill(BLACK)

# 绘制食物
pygame.draw.rect(WIN, RED, (food, food, SNAKE_SIZE, SNAKE_SIZE))

# 绘制蛇
for segment in snake:
    pygame.draw.rect(WIN, GREEN, (segment, segment, SNAKE_SIZE, SNAKE_SIZE))

# 显示游戏结束提示
if game_over:
    font = pygame.font.SysFont("arial", 50)
    text = font.render("游戏结束！按R重新开始", True, WHITE)
    WIN.blit(text, (WIDTH//2 - text.get_width()//2, HEIGHT//2 - text.get_height()//2))
    
    keys = pygame.key.get_pressed()
    if keys[pygame.K_r]:
        snake = [(WIDTH//2, HEIGHT//2)]
        snake_direction = (0, 0)
        food = (random.randint(0, (WIDTH-SNAKE_SIZE)//SNAKE_SIZE)*S