原题链接 对于以u为根的子树,后代节点的dfn显然比他的dfn大,我们可以记录一下回溯到u的dfn,显然这两个dfn构成了一个连续区间,代表u及u的子树 剩下的就和树剖一样了 #include<cstdio> #include<algorithm> #include<cstring> #define N 100010 typedef long long ll; using namespace std; int ecnt,head[N],son[N],fa[N],sz[N…
ιYou are given a tree (an acyclic undirected connected graph) with N nodes, and edges numbered 1, 2, 3...N-1. We will ask you to perfrom some instructions of the following form: CHANGE i ti : change the cost of the i-th edge to tior QUERY a b : ask f…