SPOJ QTREE2 Query on a tree II

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倍增水题……

本来还想用LCT做的……然后发现根本不需要

 //minamoto
 #include<bits/stdc++.h>
 using namespace std;
 #define getc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
 char buf[<<],*p1=buf,*p2=buf;
 inline int read(){
     #define num ch-'0'
     char ch;bool flag=;int res;
     while(!isdigit(ch=getc()))
     (ch=='-')&&(flag=true);
     for(res=num;isdigit(ch=getc());res=res*+num);
     (flag)&&(res=-res);
     #undef num
     return res;
 }
 inline bool isop(char ch){
     return ch=='I'||ch=='H'||ch=='O';
 }
 inline char readop(){
     char ch;
     while(!isop(ch=getc()));
     return ch;
 }
 const int N=;
 int head[N],Next[N<<],edge[N<<],ver[N<<],fa[N][],d[N],dist[N];
 int n,m,tot;
 inline void add(int u,int v,int e){
     ver[++tot]=v,Next[tot]=head[u],head[u]=tot,edge[tot]=e;
     ver[++tot]=u,Next[tot]=head[v],head[v]=tot,edge[tot]=e;
 }
 void dfs(int u,int f){
     d[u]=d[f]+,fa[u][]=f;
     for(int i=;(<<i)<=d[u];++i) fa[u][i]=fa[fa[u][i-]][i-];
     for(int i=head[u];i;i=Next[i]){
         int v=ver[i];
         if(v==f) continue;
         dist[v]=dist[u]+edge[i],dfs(v,u);
     }
 }
 int LCA(int x,int y){
     if(d[x]<d[y]) swap(x,y);
     for(int i=;i>=;--i)
     if(d[fa[x][i]]>=d[y]) x=fa[x][i];
     if(x==y) return x;
     for(int i=;i>=;--i)
     if(fa[x][i]!=fa[y][i])
     x=fa[x][i],y=fa[y][i];
     return fa[x][];
 }
 int querylen(int x,int y,int k){
     int lca=LCA(x,y);
     if(d[x]-d[lca]+>=k){
         int ans=d[x]-k+;
         for(int i=;i>=;--i)
         if((<<i)<=d[x]-ans) x=fa[x][i];
         return x;
     }
     else{
         int ans=d[lca]*+k-d[x]-;
         for(int i=;i>=;--i){
             if(d[y]-(<<i)>=ans) y=fa[y][i];
         }
         return y;
     }
 }
 int main(){
     //freopen("testdata.in","r",stdin);
     int q=read();
     while(q--){
         memset(head,,sizeof(head));
         memset(fa,,sizeof(fa));
         d[]=dist[]=,tot=;
         int n=read();
         for(int i=;i<n;++i){
             int u=read(),v=read(),e=read();
             add(u,v,e);
         }
         dfs(,);
         bool flag=true;
         while(flag){
             char op=readop();
             switch(op){
                 case 'O':flag=false;break;
                 case 'I':{
                     int u=read(),v=read();
                     int lca=LCA(u,v);
                     printf("%d\n",dist[u]+dist[v]-*dist[lca]);
                     break;
                 }
                 case 'H':{
                     int u=read(),v=read(),k=read();
                     printf("%d\n",querylen(u,v,k));
                     break;
                 }
             }
         }
         puts("");
     }
     return ;
 }