save project

snake.py

@@ -71,6 +71,9 @@ while True:
         score+=1
     else:     
         position.pop(0)
+    if x<0 or x>630 or y<0 or y>450:
+        exit()
+
     # 将果实画上去
     screen.blit(food, (apple_x, apple_y))
     info="score"+str(score)