treap修订

 #include<cstdio>
 #include<cmath>
 #include<algorithm>
 #include<ctime>
 #include<queue>
 #include<cctype>
 #include<cstring>
 #include<iostream>
 #define PAU putchar(' ')
 #define ENT putchar('\n')
 #define CH for(int d=0;d<=1;d++) if(ch[d])
 using namespace std;
 const int maxn=+;
 struct node{
     node*ch[];int r,v,siz;
     void init(){r=rand();siz=;ch[]=ch[]=NULL;return;}
     void update(){siz=;CH{siz+=ch[d]->siz;}return;}
 }treap[maxn],*root[maxn],*nodecnt=treap;
 queue<node*>RAM;
 node*newnode(){
     node*x;
     if(!RAM.empty()) x=RAM.front(),RAM.pop();
     else x=nodecnt++;
     x->init();return x;
 }
 void del(node*&x){RAM.push(x);return;}
 void rotate(node*&x,int d){
     node*k=x->ch[d^];x->ch[d^]=k->ch[d];k->ch[d]=x;
     x->update();k->update();x=k;return;
 }
 void insert(node*&x,int v){
     if(!x) x=newnode(),x->v=v;
     else{
         int d=v>x->v;insert(x->ch[d],v);
         if(x->ch[d]->r>x->r) rotate(x,d^);
         else x->update();
     } return;
 }
 void remove(node*&x,int v){
     if(x->v==v){
         if(x->ch[]&&x->ch[]){
             int d=x->ch[]->r>x->ch[]->r;
             rotate(x,d);remove(x->ch[d],v);
         }
         else{
             node*k=x;
             if(x->ch[]) x=x->ch[];
             else x=x->ch[];
             del(k);
         }
     }
     else remove(x->ch[v>x->v],v);
     if(x) x->update();return;
 }
 void print(node*&x){
     if(!x) return;
     print(x->ch[]);
     printf("%d ",x->v);
     print(x->ch[]);
     return;
 }
 int find(node*x,int rank){
     if(x->siz<rank||rank<) return -;
     int kth=x->ch[]?x->ch[]->siz+:;
     if(kth==rank) return x->v;
     if(kth>rank) return find(x->ch[],rank);
     else return find(x->ch[],rank-kth);
 }
 int fa[maxn];
 int findset(int x){return x==fa[x]?x:fa[x]=findset(fa[x]);}
 void merge(node*&x,node*&y){
     if(!y)return;if(!x){x=y;del(y);return;}
     merge(x,y->ch[]);
     merge(x,y->ch[]);
     insert(x,y->v);
     return;
 }
 void merge(int a,int b){
     a=findset(a);b=findset(b);
     if(a==b) return;
     if(root[a]->siz<root[b]->siz) swap(a,b);
     merge(root[a],root[b]);fa[b]=a;
     return;
 }
 inline int read(){
     int x=,sig=;char ch=getchar();
     while(!isdigit(ch)){if(ch=='-')sig=-;ch=getchar();}
     while(isdigit(ch))x=*x+ch-'',ch=getchar();
     return x*=sig;
 }
 inline char readc(){
     char ch=getchar();
     while(!isalpha(ch)) ch=getchar();
     return ch;
 }
 inline void write(int x){
     if(x==){putchar('');return;}if(x<)putchar('-'),x=-x;
     int len=,buf[];while(x)buf[len++]=x%,x/=;
     for(int i=len-;i>=;i--)putchar(buf[i]+'');return;
 }
 int n,q,v[maxn];
 void init(){
     srand(time());
     n=read();q=read();
     for(int i=;i<=n;i++) root[i]=newnode(),v[i]=root[i]->v=read(),fa[i]=i;
     return;
 }
 void work(){
     int a,b;char tp;
     while(q--){
         tp=readc();a=read();b=read();
         if(tp=='b') merge(a,b);
         else if(tp=='q') write(find(root[findset(a)],b)),ENT;
         else{
             remove(root[findset(a)],v[a]);
             insert(root[findset(a)],b);
             v[a]=b;
         }
     }
     return;
 }
 void print(){
     return;
 }
 int main(){init();work();print();return ;}