使用python 写一个贪吃蛇完整项目，蛇的长度3.苹果为1

好的，以下是一个贪吃蛇的完整项目，蛇的长度为3，每次吃到苹果会增加1，游戏结束条件为撞墙或者撞到自己。代码如下：

import pygame
import random

# 初始化 Pygame
pygame.init()

# 设置游戏窗口大小和标题
screen_width = 640
screen_height = 480
screen = pygame.display.set_mode((screen_width, screen_height))
pygame.display.set_caption("Snake Game")

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

# 设置字体
font = pygame.font.SysFont(None, 25)

# 定义蛇的初始位置和方向
snake_block_size = 10
snake_speed = 15
snake_list = []
snake_length = 3
snake_x = screen_width // 2
snake_y = screen_height // 2
snake_direction = "right"

# 定义苹果的初始位置
apple_block_size = 10
apple_x = random.randrange(0, screen_width - apple_block_size, apple_block_size)
apple_y = random.randrange(0, screen_height - apple_block_size, apple_block_size)

# 定义游戏结束函数
def game_over():
    game_over_text = font.render("Game Over!", True, white)
    screen.blit(game_over_text, [screen_width // 2 - 50, screen_height // 2])
    pygame.display.flip()
    pygame.time.wait(2000)
    pygame.quit()
    quit()

# 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_LEFT and snake_direction != "right":
                snake_direction = "left"
            elif event.key == pygame.K_RIGHT and snake_direction != "left":
                snake_direction = "right"
            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"
    
    # 移动蛇
    if snake_direction == "right":
        snake_x += snake_block_size
    elif snake_direction == "left":
        snake_x -= snake_block_size
    elif snake_direction == "up":
        snake_y -= snake_block_size
    elif snake_direction == "down":
        snake_y += snake_block_size
    
    # 判断是否吃到苹果
    if snake_x == apple_x and snake_y == apple_y:
        apple_x = random.randrange(0, screen_width - apple_block_size, apple_block_size)
        apple_y = random.randrange(0, screen_height - apple_block_size, apple_block_size)
        snake_length += 1
    
    # 判断是否撞墙
    if snake_x >= screen_width or snake_x < 0 or snake_y >= screen_height or snake_y < 0:
        game_over()
    
    # 判断是否撞到自己
    head = []
    head.append(snake_x)
    head.append(snake_y)
    snake_list.append(head)
    if len(snake_list) > snake_length:
        del snake_list[0]
    for block in snake_list[:-1]:
        if block == head:
            game_over()

    # 绘制游戏画面
    screen.fill(black)
    pygame.draw.rect(screen, red, [apple_x, apple_y, apple_block_size, apple_block_size])
    for block in snake_list:
        pygame.draw.rect(screen, white, [block[0], block[1], snake_block_size, snake_block_size])
    pygame.display.flip()

    # 控制游戏速度
    clock = pygame.time.Clock()
    clock.tick(snake_speed)

# 退出游戏
pygame.quit()
quit()

在这个项目中，先定义了一些常量和变量，包括蛇和苹果的位置和大小、游戏窗口大小、颜色等。然后在游戏循环中，处理用户输入和更新游戏状态，包括移动蛇、判断是否吃到苹果、是否撞墙或撞到自己等，最后绘制游戏画面。游戏结束后会显示 "Game Over!" 文字，并等待2秒后退出游戏。

希望这个项目能够帮助你学习 Python 和 Pygame。