save project

snake.py

@@ -52,13 +52,15 @@ while True:
         y -= 30
     else:
         y += 30
+    
+    position.append((x, y))
     if x==apple_x and y==apple_y:
         a=random.randint(1,22)
         b=random.randint(1,16)
         apple_x=a*30-30
         apple_y=b*30-30
-    position.append((x, y))
-    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