save project

snake.py

@@ -61,6 +61,7 @@ while True:
 
     apple_x = num * 30 - 30
     apple_y = num * 30 - 30
+    if x <  0 or x > 630 or y 0 or y >450:
     # 将背景图画上去
     screen.blit(background, (0, 0))
     # 将贪吃蛇的头画上去