Solution -「CF 1303G」Sum of Prefix Sums
DescriptionLink.对于一棵树,选出一条链 $(u,v)$,把链上结点从 $u$ 到 $v$ 放成一个 长度 $l$ 的数组,使得 $\sum_{i=1}^{l}\sum_{j=1}...
In mathematics you don't understand things, you just get used to them.
In mathematics you don't understand things, you just get used to them.