save project

snake.py

@@ -57,7 +57,8 @@ while True:
     if x==apple_x and y==apple_y:
         apple_x=random.randint(0,21)*30
         apple_y=random.randint(0,15)*30
-    position.pop(0)
+    else:
+        position.pop(0)
     # 将背景图画上去
     screen.blit(background, (0, 0))
     # 将贪吃蛇的头画上去