save project

snake.py

@@ -54,12 +54,13 @@ while True:
     else:
         y += 30
     position.append((x, y))
-    position.pop(0)
     if apple_x == x and apple_y == y:
         num1 = random.randint(1,22)
         apple_x = num1 * 30
         num2 = random.randint(0,16)
         apple_y = num2 * 30
+    else:
+        position.pop(0)
     #把背景画上去
     screen.blit(background, (0, 0))
     # 将贪吃蛇的头画上去