save project

snake.py

@@ -65,8 +65,10 @@ while True:
         apple_y = num2*30-30
         score+=1
     else:
-        position.pop(0)        
-    
+        position.pop(0)
+
+    if x<0 or x>630 or y<0 or y>450:
+        exit()
     position.append((x, y))
     
     # 将背景图画上去