编一个贪吃re

贪吃蛇是一款经典的游戏，下面是一个简单的贪吃蛇实现：

# 贪吃蛇实现
# author: AI

# 定义方向常量
LEFT = 1
UP = 2
RIGHT = 3
DOWN = 4

# 定义初始状态
snake = [(0, 0), (0, 1), (0, 2)]
direction = RIGHT

# 定义移动函数
def move():
    global snake, direction
    # 计算蛇头位置
    head = snake[-1]
    if direction == LEFT:
        new_head = (head[0], head[1]-1)
    elif direction == UP:
        new_head = (head[0]-1, head[1])
    elif direction == RIGHT:
        new_head = (head[0], head[1]+1)
    else:
        new_head = (head[0]+1, head[1])
    # 向蛇尾添加新的蛇头
    snake.append(new_head)
    # 删除蛇尾
    snake.pop(0)

# 定义更新方向函数
def update_direction(new_direction):
    global direction
    # 判断是否可以改变方向
    if new_direction == LEFT and direction != RIGHT:
        direction = new_direction
    elif new_direction == UP and direction != DOWN:
        direction = new_direction
    elif new_direction == RIGHT and direction != LEFT:
        direction = new_direction
    elif new_direction == DOWN and direction != UP:
        direction = new_direction

# 开始游戏
while True:
    # 打印当前状态
    for i in range(10):
        for j in range(10):
            if (i, j) in snake:
                print('o', end='')
            else:
                print('.', end='')
        print('')
    # 获取用户输入
    user_input = input('请输入方向 (L/U/R/D): ')
    # 更新方向
    if user_input == 'L':
        update_direction(LEFT)
    elif user_input == 'U':
        update_direction(UP)
    elif user_input == 'R':
        update_direction(RIGHT)
    elif user_input == 'D':
        update_direction(DOWN)
    # 移动蛇
    move()

这段代码使用 Python 语言编写，实现了一个简单的贪吃蛇游戏。