[SDOI2011]消耗战

虚树dp

#include<cstdio>
#include<vector>
#include<iostream>
#include<algorithm>
const int maxn = 1000500;
typedef long long ll;
int n,m,k;
struct T{
    int to,nxt;
    ll v;
}way[maxn<<1];
int h[maxn],num;
inline void adde(int x,int y,ll v){
    way[++num]={y,h[x],v},h[x]=num;
    way[++num]={x,h[y],v},h[y]=num;
}
int dep[maxn],size[maxn],fa[maxn],dfn[maxn],vis[maxn],tot;
int bz[maxn][20],mn[maxn][20];
inline void dfs(int x){
    size[x]=vis[x]=1,dep[x]=dep[fa[x]]+1,dfn[x]=++tot;
    for(int i=1;i<20;++i)
        bz[x][i]=bz[bz[x][i-1]][i-1],mn[x][i]=std::min(mn[x][i-1],mn[bz[x][i-1]][i-1]);
    for(int i=h[x];i;i=way[i].nxt)
        if(!vis[way[i].to])
            *bz[way[i].to]=fa[way[i].to]=x,*mn[way[i].to]=way[i].v,dfs(way[i].to),size[x]+=size[way[i].to];
    vis[x]=0;
}
inline int lca(int x,int y){
    if(dep[x]>dep[y])std::swap(x,y);
    for(int d=dep[y]-dep[x];d;d&=d-1)y=bz[y][__builtin_ctz(d)];
    if(x==y)return x;
    for(int i=19;~i;--i)if(bz[x][i]!=bz[y][i])x=bz[x][i],y=bz[y][i];
    return *bz[x];
}
inline void down(int&x,int y){if(x>y)x=y;}
inline int get(int x,int y){
    if(dep[x]>dep[y])std::swap(x,y);
    int ans=1e9;
    for(int d=dep[y]-dep[x];d;d&=d-1)down(ans,mn[y][__builtin_ctz(d)]),y=bz[y][__builtin_ctz(d)];
    if(x!=y)exit(1);
    return ans;
}
ll f[maxn];
inline void dp(int x){
    vis[x]=1;
    for(int i=h[x];i;i=way[i].nxt)
        if(!vis[way[i].to])
            dp(way[i].to),f[x] += std::min(way[i].v,f[way[i].to]);
    vis[x]=0;
}
int st[maxn],tp;
inline void solve(){
    std::vector<int> v;
    static const auto cmp = [&](const int&x,const int&y){return dfn[x]<dfn[y];};
    std::cin >> k;
    for(int i=1,x;i<=k;++i)std::cin >> x,v.push_back(x),f[x]=1e13;
    std::sort(v.begin(),v.end(),cmp);
    for(int i=0;i+1<k;++i) v.push_back(lca(v[i],v[i+1]));
    v.push_back(1);
    std::sort(v.begin(),v.end(),cmp);
    v.erase(std::unique(v.begin(),v.end()),v.end());
    tp=0;
    for(int i:v){
        while(tp && dfn[st[tp]]+size[st[tp]]-1 < dfn[i])--tp;
        if(st[tp])adde(st[tp],i,get(i,st[tp]));
        st[++tp]=i;
    }
    dp(1);
    std::cout << f[1] << '
';
    for(int i:v)h[i]=0,f[i]=0;
    num=0;
}
int main(){
    std::ios::sync_with_stdio(false),std::cin.tie(0);
    std::cin >> n;
    for(int i=1,x,y,v;i<n;++i)std::cin >> x >> y >> v,adde(x,y,v);
    dfs(1),num=0;
    for(int i=1;i<=n;++i)h[i]=0;
    std::cin >> m;
    while(m--)solve();
}