bzoj2286: [Sdoi2011]消耗战

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
#define maxn 250005
#define inf (~0ull>>1)
#define min(x,y) (x)>(y)?(y):(x)
 
int n,tot,deg,m,top;
int now[maxn],pre[maxn*2],son[maxn*2],val[maxn*2],dfn[maxn],dep[maxn];
int a[maxn],stack[maxn];
long long dp[maxn],minval[maxn];
int f[maxn][21];
bool vis[maxn];
 
inline int read(){
    int x=0;char ch=getchar();
    for (;ch<‘0‘||ch>‘9‘;ch=getchar());
    for (;ch>=‘0‘&&ch<=‘9‘;ch=getchar()) x=x*10+ch-‘0‘;
    return x;
}
 
void add(int a,int b,int c){
    son[++tot]=b;
    pre[tot]=now[a];
    now[a]=tot;
    val[tot]=c;
}
 
void link(int a,int b,int c){
    add(a,b,c),add(b,a,c);
}
 
void dfs(int x,int fa){
    dep[x]=dep[fa]+1,dfn[x]=++deg;
    for (int p=now[x];p;p=pre[p])
        if (son[p]!=fa){
            f[son[p]][0]=x,minval[son[p]]=min(minval[x],val[p]);
            dfs(son[p],x);
        }
}
 
int lca(int a,int b){
    if (dep[a]<dep[b]) swap(a,b);int x=dep[a]-dep[b],t=0;
    for (;x;x>>=1,t++) if (x&1) a=f[a][t];
    if (a==b) return a;t=log2(dep[a])+1;
    for (;f[a][0]!=f[b][0];){
        for (;f[a][t]==f[b][t];) t--;
        a=f[a][t],b=f[b][t];
    }
    return f[a][0];
}
 
void tree_dp(int x){
    dp[x]=minval[x];long long sum=0;
    for (int p=now[x];p;p=pre[p]) tree_dp(son[p]),sum+=dp[son[p]];
    if (sum&&!vis[x]) dp[x]=min(dp[x],sum);now[x]=0;
}
 
bool cmp(int a,int b){return dfn[a]<dfn[b];}
 
int main(){
    n=read();minval[1]=inf;
    for (int i=1,aa,b,c;i<n;i++) aa=read(),b=read(),c=read(),link(aa,b,c);
    dfs(1,0); memset(now,0,sizeof(now)),tot=0; m=read();
    for (int i=1;i<=20;i++)
        for (int x=1;x<=n;x++)
            f[x][i]=f[f[x][i-1]][i-1];
    while (m--){
        int len=read();top=0;
        for (int i=1;i<=len;i++) a[i]=read(),vis[a[i]]=1;
        sort(a+1,a+len+1,cmp);
        for (int i=1;i<=len;i++){
            if (!top){stack[++top]=a[i];continue;}
            int x=lca(stack[top],a[i]);
            for (;dfn[x]<dfn[stack[top]];){
                if (dfn[x]>=dfn[stack[top-1]]){
                    add(x,stack[top],0);
                    if (stack[--top]!=x) stack[++top]=x;
                    break;
                }
                add(stack[top-1],stack[top],0),top--;
            }
            stack[++top]=a[i];
        }
        while (top>1) add(stack[top-1],stack[top],0),top--;
        tree_dp(stack[1]),printf("%lld\n",dp[stack[1]]);
        for (int i=1;i<=len;i++) vis[a[i]]=0;tot=0;
    }
    return 0;
}