帮我用python 写一段 贪吃蛇的程序

以下是一个简单的贪吃蛇程序示例，你可以在Python环境中运行它：

import pygame
import random

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

# 定义蛇类
class Snake:
    def __init__(self):
        self.body = [[100, 50], [90, 50], [80, 50]]
        self.direction = "RIGHT"
        self.score = 0
        
    def move(self):
        if self.direction == "RIGHT":
            new_head = [self.body[0][0] + 10, self.body[0][1]]
        elif self.direction == "LEFT":
            new_head = [self.body[0][0] - 10, self.body[0][1]]
        elif self.direction == "UP":
            new_head = [self.body[0][0], self.body[0][1] - 10]
        elif self.direction == "DOWN":
            new_head = [self.body[0][0], self.body[0][1] + 10]
        self.body.insert(0, new_head)
        
        # 判断是否吃到食物
        if self.body[0] == food.position:
            food.generate()
            self.score += 10
        else:
            self.body.pop()
            
    def change_direction(self, direction):
        if direction == "RIGHT" and not self.direction == "LEFT":
            self.direction = "RIGHT"
        elif direction == "LEFT" and not self.direction == "RIGHT":
            self.direction = "LEFT"
        elif direction == "UP" and not self.direction == "DOWN":
            self.direction = "UP"
        elif direction == "DOWN" and not self.direction == "UP":
            self.direction = "DOWN"
            
    def draw(self, screen):
        for segment in self.body:
            pygame.draw.rect(screen, white, pygame.Rect(segment[0], segment[1], 10, 10))
            
# 定义食物类
class Food:
    def __init__(self):
        self.position = [random.randrange(1, 50) * 10, random.randrange(1, 50) * 10]
        
    def generate(self):
        self.position = [random.randrange(1, 50) * 10, random.randrange(1, 50) * 10]
        
    def draw(self, screen):
        pygame.draw.rect(screen, red, pygame.Rect(self.position[0], self.position[1], 10, 10))
        
# 初始化游戏
pygame.init()
screen = pygame.display.set_mode((500, 500))
pygame.display.set_caption('贪吃蛇')
clock = pygame.time.Clock()

snake = Snake()
food = Food()

# 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_RIGHT:
                snake.change_direction("RIGHT")
            elif event.key == pygame.K_LEFT:
                snake.change_direction("LEFT")
            elif event.key == pygame.K_UP:
                snake.change_direction("UP")
            elif event.key == pygame.K_DOWN:
                snake.change_direction("DOWN")
                
    # 移动蛇
    snake.move()
    
    # 绘制界面
    screen.fill(black)
    snake.draw(screen)
    food.draw(screen)
    pygame.display.update()
    
    # 判断是否游戏结束
    if snake.body[0][0] < 0 or snake.body[0][0] > 490 or snake.body[0][1] < 0 or snake.body[0][1] > 490:
        running = False
        print("Game Over! Your score is:", snake.score)
        
    for segment in snake.body[1:]:
        if snake.body[0] == segment:
            running = False
            print("Game Over! Your score is:", snake.score)
            
    # 控制游戏速度
    clock.tick(10)

# 退出游戏
pygame.quit()

这段程序使用了pygame库来实现游戏界面的绘制和事件的处理，同时定义了Snake和Food两个类来实现贪吃蛇的功能，并通过循环来实现游戏的运行。