我想写个贪吃蛇小程序

很好，以下是一个简单的贪吃蛇小程序的示例代码：

import pygame
import random

# 定义一些常量
WIDTH = 640
HEIGHT = 480
FPS = 10
BLOCK_SIZE = 20

# 初始化pygame
pygame.init()
screen = pygame.display.set_mode((WIDTH, 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)

# 定义贪吃蛇的类
class Snake:
    def __init__(self):
        self.body = [(WIDTH // 2, HEIGHT // 2)]
        self.direction = "right"
    
    def move(self):
        x, y = self.body[0]
        if self.direction == "right":
            x += BLOCK_SIZE
        elif self.direction == "left":
            x -= BLOCK_SIZE
        elif self.direction == "up":
            y -= BLOCK_SIZE
        elif self.direction == "down":
            y += BLOCK_SIZE
        self.body.insert(0, (x, y))
        self.body.pop()
    
    def grow(self):
        x, y = self.body[0]
        if self.direction == "right":
            x += BLOCK_SIZE
        elif self.direction == "left":
            x -= BLOCK_SIZE
        elif self.direction == "up":
            y -= BLOCK_SIZE
        elif self.direction == "down":
            y += BLOCK_SIZE
        self.body.insert(0, (x, y))

# 定义食物的类
class Food:
    def __init__(self):
        self.x = random.randrange(0, WIDTH // BLOCK_SIZE) * BLOCK_SIZE
        self.y = random.randrange(0, HEIGHT // BLOCK_SIZE) * BLOCK_SIZE
    
    def draw(self, screen):
        pygame.draw.rect(screen, RED, (self.x, self.y, BLOCK_SIZE, BLOCK_SIZE))

# 创建贪吃蛇和食物的实例
snake = Snake()
food = Food()

# 定义游戏主循环
running = True
clock = pygame.time.Clock()
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 and snake.direction != "left":
                snake.direction = "right"
            elif event.key == pygame.K_LEFT and snake.direction != "right":
                snake.direction = "left"
            elif event.key == pygame.K_UP and snake.direction != "down":
                snake.direction = "up"
            elif event.key == pygame.K_DOWN and snake.direction != "up":
                snake.direction = "down"
    
    # 移动贪吃蛇
    snake.move()
    
    # 判断是否吃到食物
    if snake.body[0] == (food.x, food.y):
        snake.grow()
        food = Food()
    
    # 判断是否撞墙或撞到自己
    if snake.body[0][0] < 0 or snake.body[0][0] >= WIDTH or snake.body[0][1] < 0 or snake.body[0][1] >= HEIGHT:
        running = False
    for i in range(1, len(snake.body)):
        if snake.body[0] == snake.body[i]:
            running = False
    
    # 绘制屏幕
    screen.fill(BLACK)
    snake_rects = [pygame.Rect(x, y, BLOCK_SIZE, BLOCK_SIZE) for x, y in snake.body]
    pygame.draw.rect(screen, GREEN, snake_rects[0])
    pygame.draw.rect(screen, WHITE, snake_rects[0], 1)
    for rect in snake_rects[1:]:
        pygame.draw.rect(screen, GREEN, rect)
    food.draw(screen)
    pygame.display.flip()
    
    # 控制帧率
    clock.tick(FPS)

# 关闭pygame
pygame.quit()

这个程序使用了Pygame库，可以通过pip安装。运行程序后，按上下左右键控制贪吃蛇的方向，吃到食物后贪吃蛇会变长，撞到墙或自己后游戏结束