编写一个python贪吃蛇游戏

以下是一个简单的Python贪吃蛇游戏的代码，使用了Pygame库：

import pygame
import random

# 初始化Pygame
pygame.init()

# 游戏窗口大小
screen_width = 480
screen_height = 480

# 创建游戏窗口
screen = pygame.display.set_mode((screen_width, screen_height))
pygame.display.set_caption("贪吃蛇")

# 定义颜色
white = (255, 255, 255)
black = (0, 0, 0)
green = (0, 255, 0)
red = (255, 0, 0)

# 定义方向
UP = 0
DOWN = 1
LEFT = 2
RIGHT = 3

# 蛇的初始位置和长度
snake_pos = [(screen_width // 2, screen_height // 2)]
snake_len = 1

# 食物的初始位置
food_pos = (random.randint(0, screen_width // 20) * 20, random.randint(0, screen_height // 20) * 20)

# 初始方向
direction = RIGHT

# 游戏循环
running = True
while running:
    # 处理事件
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP and direction != DOWN:
                direction = UP
            elif event.key == pygame.K_DOWN and direction != UP:
                direction = DOWN
            elif event.key == pygame.K_LEFT and direction != RIGHT:
                direction = LEFT
            elif event.key == pygame.K_RIGHT and direction != LEFT:
                direction = RIGHT

    # 移动蛇
    new_head = (snake_pos[0][0], snake_pos[0][1])
    if direction == UP:
        new_head = (new_head[0], new_head[1] - 20)
    elif direction == DOWN:
        new_head = (new_head[0], new_head[1] + 20)
    elif direction == LEFT:
        new_head = (new_head[0] - 20, new_head[1])
    elif direction == RIGHT:
        new_head = (new_head[0] + 20, new_head[1])

    # 判断是否吃到食物
    if new_head == food_pos:
        food_pos = (random.randint(0, screen_width // 20) * 20, random.randint(0, screen_height // 20) * 20)
        snake_len += 1
    else:
        snake_pos.pop()

    # 判断是否游戏结束
    if new_head[0] < 0 or new_head[0] >= screen_width or new_head[1] < 0 or new_head[1] >= screen_height or new_head in snake_pos:
        running = False

    # 更新蛇的位置
    snake_pos.insert(0, new_head)

    # 绘制画面
    screen.fill(black)
    for pos in snake_pos:
        pygame.draw.rect(screen, green, (pos[0], pos[1], 20, 20))
    pygame.draw.rect(screen, red, (food_pos[0], food_pos[1], 20, 20))
    pygame.display.update()

# 退出游戏
pygame.quit()

这个游戏存在一些问题，例如蛇碰到边界或者自己的身体就会游戏结束，不能够重新开始游戏等，可以根据需求进行修改和完善。