【bzoj2286】[Sdoi2011]消耗战

虚树入门题；

 

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<ctime>
#include<cmath>
#include<iostream>
using namespace std;
#define LL long long
#define pii pair<int,int> 
#define up(i,j,n) for(int i=(j);i<=(n);i++)
#define FILE "dealing"
int read(){
	int f=1,x=0,ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9')x=(x<<1)+(x<<3)+ch-'0',ch=getchar();
	return f*x;
}
const int maxn=505000,inf=1000000000;
int n,m,lim,k;
struct node{int y,next,v;}e[maxn],E[maxn];
LL linkk[maxn],len=0,linker[maxn],pre[maxn],vis[maxn],Len,d[maxn][31],fa[maxn][31],dfs_clock,dep[maxn],q[maxn],top=0,f[maxn];
pii a[maxn];
void insert(int x,int y,int v){e[++len].y=y;e[len].next=linkk[x];linkk[x]=len;e[len].v=v;}
void insert2(int x,int y,int v){E[++Len].y=y;E[Len].next=linker[x];linker[x]=Len;E[Len].v=v;}
void dfs(int x){
	pre[x]=++dfs_clock;
	for(int i=linker[x];i;i=E[i].next){
		if(E[i].y==fa[x][0])continue;
		fa[E[i].y][0]=x;
		d[E[i].y][0]=E[i].v;
		dep[E[i].y]=dep[x]+1;
		dfs(E[i].y);
	}
}
int lca(int x,int y){
	if(dep[x]>dep[y])swap(x,y);
	for(int i=lim;i>=0;i--)if(dep[y]-dep[x]>=(1<<i))y=fa[y][i];
	if(x==y)return x;
	for(int i=lim;i>=0;i--)if(fa[y][i]!=fa[x][i])x=fa[x][i],y=fa[y][i];
	return fa[x][0];
}
LL fmin(LL x,LL y){
	if(dep[x]>dep[y])swap(x,y);
	LL Min=inf;
	for(int i=lim;i>=0;i--)if(dep[y]-dep[x]>=(1<<i))Min=min((LL)Min,d[y][i]),y=fa[y][i];
	return Min;
}
void dp(int x,int fa,int w){
	if(vis[x]&&x!=1){f[x]=w;return;}
	else {
		f[x]=0;
		for(int i=linkk[x];i;i=e[i].next){
			if(e[i].y==fa)continue;
			dp(e[i].y,x,e[i].v);
			f[x]+=f[e[i].y];
		}
		if(x!=1)f[x]=min(f[x],(LL)w);
	}
}
void clear(int x,int fa){
	for(int i=linkk[x];i;i=e[i].next){
		if(e[i].y==fa)continue;
		clear(e[i].y,x);
	}
	f[x]=0;
	linkk[x]=0;
}
int main(){
	//freopen("dealing.in","r",stdin);
	//freopen("dealing.out","w",stdout);
	n=read();lim=(int)log2(n*1.0+1)+1;
	up(i,1,n-1){
		int x=read(),y=read(),v=read();
		insert2(x,y,v);insert2(y,x,v);
	}
	dfs(1);
	up(j,1,lim)up(i,1,n)fa[i][j]=fa[fa[i][j-1]][j-1],d[i][j]=min(d[i][j-1],d[fa[i][j-1]][j-1]);
	m=read();
	while(m--){
		k=read()+1;a[k].second=1;
		up(i,1,k-1)a[i].second=read();
		up(i,1,k)a[i].first=pre[a[i].second],vis[a[i].second]=1;vis[1]=0;
		sort(a+1,a+k+1);
		up(i,1,k){
			int x=a[i].second;
			if(!top){q[++top]=x;continue;}
			int Lca=lca(x,q[top]);
			if(Lca==q[top]){q[++top]=x;continue;}
			while(dep[q[top-1]]>dep[Lca]){
				LL v=fmin(q[top],q[top-1]);
				insert(q[top],q[top-1],v);insert(q[top-1],q[top],v);
				top--;
			}
			LL v=fmin(Lca,q[top]);
			insert(Lca,q[top],v);insert(q[top],Lca,v);
			top--;
			if(q[top]!=Lca)q[++top]=Lca;q[++top]=x;
		}
		while(top!=1){
			LL v=fmin(q[top],q[top-1]);
			insert(q[top],q[top-1],v);
			insert(q[top-1],q[top],v);
			top--;
		}
		dp(1,0,0);top=0;
		printf("%lld\n",f[1]);
		clear(1,0);
		up(i,1,k)vis[a[i].second]=0;len=0;
	}
	return 0;
}