BZOJ 2959: 长跑 lct 双联通分量 并查集 splay

http://www.lydsy.com/JudgeOnline/problem.php?id=2959

用两个并查集维护双联通分量的编号和合并。

 #include<iostream>
 #include<cstdio>
 #include<algorithm>
 #include<cstring>
 #include<cmath>
 #include<queue>
 using namespace std;
 const int maxn=;
 int n,m;
 int fa[maxn]={},ch[maxn][]={},siz[maxn]={},val[maxn]={},rev[maxn];
 int shu[maxn]={};
 int sta[maxn]={},tail=;
 int p[maxn]={},b[maxn]={};
 inline int read(){
     int x=;int f=;char ch=getchar();
     while(ch<''||ch>''){
         if(ch=='-')f=-;
         ch=getchar();
     }
     while(''<=ch&&ch<=''){x=x*+ch-'';ch=getchar();}
     return x*f;
 }
 int findfa(int x){
     if(p[x]==x)return x;
     return p[x]=findfa(p[x]);
 }
 int bel(int x){
     if(b[x]==x)return x;
     return b[x]=bel(b[x]);
 }
 inline bool isroot(int x){return ch[fa[x]][]!=x&&ch[fa[x]][]!=x;}
 inline void updata(int x){ siz[x]=siz[ch[x][]]+siz[ch[x][]]+val[x];}
 inline void rotate(int x){
     int y=fa[x];int fy=fa[y];
     int l=ch[y][]==x?:;int r=l^;
     if(!isroot(y)){
         if(ch[fy][]==y)ch[fy][]=x;
         else ch[fy][]=x;
     }
     fa[ch[x][r]]=y;fa[y]=x;fa[x]=fy;
     ch[y][l]=ch[x][r]; ch[x][r]=y;
     updata(y);
 }
 inline void pushdown(int x){
     if(rev[x]){
         swap(ch[x][],ch[x][]);
         if(ch[x][])rev[ch[x][]]^=;
         if(ch[x][])rev[ch[x][]]^=;
         rev[x]=;
     }
 }
 inline void splay(int x){
     x=bel(x);fa[x]=bel(fa[x]);
     int y,fy,w=x;
     sta[++tail]=w;
     while(!isroot(w)){
         fa[w]=bel(fa[w]);sta[++tail]=fa[w];
         fa[fa[w]]=bel(fa[fa[w]]);
         w=fa[w];
     }
     while(tail)pushdown(sta[tail--]);

     while(!isroot(x)){
         y=fa[x];fy=fa[y];
         if(!isroot(y)){
             if((ch[y][]==x)^(ch[fy][]==y))rotate(x);
             else rotate(y);
         }rotate(x);
     }updata(x);
 }
 inline void Access(int x){
     int y=;
     while(x){
         x=bel(x);
         splay(x);ch[x][]=y;
         updata(x);
         y=x;x=fa[x];
     }
 }
 inline void Reverse(int x){
     Access(x);splay(x);
     rev[x]^=;
 }
 inline void Link(int x,int y){
     Reverse(x);fa[x]=y;
 }
 queue< int >q;
 inline void Merge(int x,int y){
     Reverse(y);Access(x);splay(x);
     int cnt=siz[x];
     q.push(x);
     while(!q.empty()){
         x=q.front();q.pop();
         if(ch[x][])q.push(ch[x][]);
         if(ch[x][])q.push(ch[x][]);
         b[bel(x)]=b[bel(y)];
         val[x]=siz[x]=fa[x]=ch[x][]=ch[x][]=;
     }
     val[y]=siz[y]=cnt;fa[y]=;
 }
 int main(){
     //freopen("now.in","r",stdin);
     n=read();m=read();;
     for(int i=;i<=n;i++){val[i]=read();shu[i]=val[i];siz[i]=val[i];}
     for(int i=;i<=n;i++)p[i]=i,b[i]=i;
     int op,x,y,xx,yy;
     for(int i=;i<=m;i++){
         op=read();x=read();y=read();
         if(op==){
             x=bel(x);y=bel(y);
             if(x!=y){
                 xx=findfa(x);yy=findfa(y);
                 if(xx==yy) Merge(x,y);
                 else {Link(x,y);p[xx]=yy;}
             }
         }
         else if(op==){
             xx=bel(x);
             if(shu[x]!=y){
                 Access(xx);splay(xx);
                 siz[xx]+=y-shu[x];
                 val[xx]+=y-shu[x];
                 shu[x]=y;
             }
         }
         else{
             x=bel(x);y=bel(y);
             if(findfa(x)!=findfa(y)){
                 printf("-1\n");
             }
             else{
                 Reverse(x);Access(y);splay(y);
                 printf("%d\n",siz[y]);
             }
         }
     }
     return ;
 }

注意一下双联通分量编号的维护