bzoj3991: [SDOI2015]寻宝游戏--DFS序+LCA+set动态维护

之前貌似在hdu还是poj上写过这道题。

 #include<stdio.h>
 #include<string.h>
 #include<algorithm>
 #include<set>
 #define maxn 100010
 #define INF 0x7fffffff
 using namespace std;
 struct node{
     int to,cost,next;
 }e[maxn*];
 int n,m,u,v,c,logn,tot,time,x;
 ],head[maxn],dep[maxn],id[maxn],pos[maxn];
 ];
 bool flag[maxn];
 long long ans,t;
 set<int> st;

 inline void insert(int u, int v, int c){
     e[++tot].to=v;
     e[tot].cost=c;
     e[tot].next=head[u];
     head[u]=tot;
 }

 inline void dfs(int u, int f, int d, int c){
     pos[u]=++time; id[time]=u;
     dep[u]=d;
     fa[u][]=f; dis[u][]=c;
     ; i<=logn; i++) fa[u][i]=fa[fa[u][i-]][i-];
     ; i<=logn; i++) dis[u][i]=dis[u][i-]+dis[fa[u][i-]][i-];
     ; i=e[i].next)
         ,e[i].cost);
 }

 inline long long lca(int u, int v){
     ;
     if (dep[u]>dep[v]) swap(u,v);
     while (dep[u]<dep[v]){
         ; i--)
             if (dep[u]<dep[fa[v][i]]){
                 sum+=dis[v][i];
                 v=fa[v][i];
             }
         sum+=dis[v][];
         v=fa[v][];
     }
     if (u==v) return sum;
     ; i--)
         if (fa[u][i]!=fa[v][i]){
             sum+=dis[u][i]+dis[v][i];
             u=fa[u][i]; v=fa[v][i];
         }
     sum+=dis[u][]+dis[v][];
     return sum;
 }

 int main(){
     scanf("%d%d", &n, &m);
     logn=; <<logn)<n) logn++;
     tot=-; memset(head,-,sizeof(head));
     ; i<n; i++){
         scanf("%d%d%d", &u, &v, &c);
         insert(u,v,c);
         insert(v,u,c);
     }
     time=;
     dfs(,,,);
     st.insert(-INF); st.insert(INF);
     while (m--){
         scanf("%d", &x);
         if (!flag[x]){
             flag[x]=;
             int l=*--st.lower_bound(pos[x]), r=*st.upper_bound(pos[x]);
             st.insert(pos[x]);
             if (l !=-INF) ans+=lca(id[l],x);
             if (r != INF) ans+=lca(x,id[r]);
             if (l!=-INF && r!=INF) ans-=lca(id[l],id[r]);
         }
         else{
             flag[x]=;
             st.erase(pos[x]);
             int l=*--st.lower_bound(pos[x]), r=*st.upper_bound(pos[x]);
             if (l!=-INF) ans-=lca(id[l],x);
             if (r!= INF) ans-=lca(x,id[r]);
             if (l!=-INF && r!=INF) ans+=lca(id[l],id[r]);
         }
         ){
             int l=*++st.lower_bound(-INF), r=*--st.lower_bound(INF);
             t=lca(id[l],id[r]);
         }
         printf("%lld\n", ans+t);
     }
     ;
 }