贪吃蛇代码,屏幕会出现蛇以外的随机的点，蛇的头部碰到即吸收这一点且长度变长一格，其他部位碰到这一点游戏结束-Snake code, the screen will appear random point outside the snake, the snake' s head hit that absorb it and the length becomes longer a grid, other parts of the encounter that the game is over