@[Dragon_Horse](/user/394167) 病因：差分数组做完后出现负数。
by _Sunmoon_ @ 2022-11-17 23:08:49
@[Dragon_Horse](/user/394167) 错误，答案是lca写错，判断dep是什么意思啊。
by Usada_Pekora @ 2022-11-17 23:10:58
https://www.luogu.com.cn/record/94403379
by Usada_Pekora @ 2022-11-17 23:13:25