BZOJ 3991: [SDOI2015]寻宝游戏

/**************************************************************
    Problem: 3991
    User: BeiYu
    Language: C++
    Result: Accepted
    Time:10800 ms
    Memory:92712 kb
****************************************************************/
 
#include <bits/stdc++.h>
using namespace std;
 
#define mpr make_pair
#define x first
#define y second
 
typedef long long LL;
typedef pair<int,LL> pr;
 
const int N = 200050;
const int M = 22;
 
inline int in(int x=0,char ch=getchar()) { while(ch>‘9‘ || ch<‘0‘) ch=getchar();
    while(ch>=‘0‘ && ch<=‘9‘) x=x*10+ch-‘0‘,ch=getchar();return x; }
 
int n,m,cnt,q;
vector<pr> h[N];
int mk[N];
LL pw2[N],lg2[N];
LL dfn[N],d[N],dis[N],pos[N];
LL f[N][M],g[N][M];
LL ans;
set<pr> S;
 
void AddEdge(int u,int v,LL w) {
    h[u].push_back(mpr(v,w)),h[v].push_back(mpr(u,w));
}
void DFS(int u,int fa,LL dp) {
    dfn[++m]=u,pos[u]=m,f[m][0]=u,d[u]=d[fa]+1,dis[u]=dp;
    for(int i=0,v;i<(int)h[u].size();i++) if((v=h[u][i].x)!=fa) {
        DFS(v,u,dp+h[u][i].y),dfn[++m]=u,f[m][0]=u;
    }
}
void init() {
    memset(d,0x3f,sizeof(d));
    DFS(1,1,0);
    pw2[0]=1;for(int i=1;i<M;i++) pw2[i]=pw2[i-1]<<1;
    lg2[0]=-1;for(int i=1;i<N;i++) lg2[i]=lg2[i>>1]+1;
    for(int j=1;j<M;j++) for(int i=1;i<=m;i++) if(i+pw2[j]-1<=m){
        int u=f[i][j-1],v=f[i+pw2[j-1]][j-1];
        if(d[u]<d[v]) f[i][j]=u;else f[i][j]=v;
    }
}
int LCA(int u,int v) {
    if(pos[u]>pos[v]) swap(u,v);
    u=pos[u],v=pos[v];
    int lg=lg2[v-u+1];
    return d[f[u][lg]]<d[f[v-pw2[lg]+1][lg]]?f[u][lg]:f[v-pw2[lg]+1][lg];
}
LL Dis(int u,int v) { return dis[u]+dis[v]-2*dis[LCA(u,v)]; }
void Add(int x) {
    if(S.empty()) { S.insert(mpr(pos[x],x));return; }
    set<pr>::iterator bf=S.lower_bound(mpr(pos[x],x)),bd=bf;
    if(bf==S.begin()) bf=S.end();
    bf--;
    if(bd==S.end()) bd=S.begin();
    ans-=Dis((*bf).y,(*bd).y);
    ans+=Dis(x,(*bf).y),ans+=Dis(x,(*bd).y);
    S.insert(mpr(pos[x],x));
}
void Del(int x) {
    S.erase(mpr(pos[x],x));
    if(S.empty()) return;
    set<pr>::iterator bf=S.lower_bound(mpr(pos[x],x)),bd=bf;
    if(bf==S.begin()) bf=S.end();
    bf--;
    if(bd==S.end()) bd=S.begin();
    ans-=Dis((*bf).y,x),ans-=Dis((*bd).y,x);
    ans+=Dis((*bf).y,(*bd).y);
    S.erase(mpr(pos[x],x));
}
 
int main() {
    n=in(),q=in();
    for(int i=1,u,v,w;i<n;i++) u=in(),v=in(),w=in(),AddEdge(u,v,w);
    init();
    for(;q--;) {
        int x=in();
        if(mk[x]) Del(x),mk[x]=0;
        else Add(x),mk[x]=1;
        printf("%lld\n",ans);
    }return 0;
}