用LCA也不麻烦吧，虽然说最后还要算个前缀和
~~然而我也是树剖过的~~
by NaCly_Fish @ 2019-03-08 19:56:04
@[Froggy](/space/show?uid=100285) ~~说实话我不会树上差分时也写了树剖。。。~~
by _louhc @ 2019-03-08 20:23:24
~~同用树剖...~~
by _xcc_ @ 2019-03-17 08:05:44
我995ms
by 01190220csl @ 2019-06-25 19:56:10