写一段贪吃蛇的程序代码

这是一个用 Python 语言编写的简单的贪吃蛇游戏代码示例：

import turtle
import time

# 设置窗口大小和标题
turtle.setup(width=600, height=600)
turtle.title("贪吃蛇")

# 隐藏海龟图形
turtle.hideturtle()

# 设置速度
turtle.speed(10)

# 画游戏界面的边界
turtle.pensize(5)
turtle.penup()
turtle.goto(-290, 290)
turtle.pendown()
for i in range(4):
    turtle.forward(580)
    turtle.right(90)

# 设置食物的位置
food = turtle.Turtle()
food.speed(0)
food.shape("circle")
food.color("red")
food.penup()
food.goto(0, 100)

# 设置蛇头
head = turtle.Turtle()
head.speed(0)
head.shape("square")
head.color("green")
head.penup()
head.goto(0, 0)
head.direction = "stop"

# 设置蛇身
segments = []

# 设置方向
def move():
    if head.direction == "up":
        y = head.ycor()
        head.sety(y + 20)

    if head.direction == "down":
        y = head.ycor()
        head.sety(y - 20)

    if head.direction == "left":
        x = head.xcor()
        head.setx(x - 20)

    if head.direction == "right":
        x = head.xcor()
        head.setx(x + 20)

# 按键处理函数
def change_direction(key):
    if key == "Up":
        head.direction = "up"
    if key == "Down":
        head.direction = "down"
    if key == "Left":
        head.direction = "left"
    if key == "Right":
        head.direction = "right"

# 监听键盘事件
turtle.listen()
turtle.onkeypress(change_direction, "Up")
turtle.onkeypress(change_direction, "Down")
turtle.onkeypress(change_direction, "Left")
turtle.onkeypress(change_direction, "Right")

# 游戏主循环
while True:
    turtle.update()
    time.sleep(0.1)
    move()

    # 判断蛇头是否吃