你的 `pushdown` 写挂了，更新子节点值的时候，要用父节点的tag更新，而不是value
by quchenming @ 2023-10-09 09:52:37
你的程序里是把 `v` 改成 `add`
by quchenming @ 2023-10-09 10:01:19
@[quchenming](/user/363995) 过了，感谢
by hys52 @ 2023-10-09 10:06:56
@[hys52](/user/461572) 没事
by quchenming @ 2023-10-09 10:16:45