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题解

写了一下\(FHQ\ Treap\)

//minamoto

#include<bits/stdc++.h>

#define R register

#define inline __inline__ __attribute__((always_inline))

#define fp(i,a,b) for(R int i=(a),I=(b)+1;i<I;++i)

#define fd(i,a,b) for(R int i=(a),I=(b)-1;i>I;--i)

#define go(u) for(int i=head[u],v=e[i].v;i;i=e[i].nx,v=e[i].v)

template<class T>inline bool cmax(T&a,const T&b){return a<b?a=b,1:0;}

template<class T>inline bool cmin(T&a,const T&b){return a>b?a=b,1:0;}

using namespace std;

char buf[1<<21],*p1=buf,*p2=buf;

inline char getc(){return p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++;}

int read(){

    R int res,f=1;R char ch;

    while((ch=getc())>'9'||ch<'0')(ch=='-')&&(f=-1);

    for(res=ch-'0';(ch=getc())>='0'&&ch<='9';res=res*10+ch-'0');

    return res*f;

}

char sr[1<<21],z[20];int K=-1,Z=0;

inline void Ot(){fwrite(sr,1,K+1,stdout),K=-1;}

void print(R int x){

    if(K>1<<20)Ot();if(x<0)sr[++K]='-',x=-x;

    while(z[++Z]=x%10+48,x/=10);

    while(sr[++K]=z[Z],--Z);sr[++K]='\n';

}

unsigned int aaa=19260817;

inline unsigned int rd(){aaa^=aaa>>15,aaa+=aaa<<12,aaa^=aaa>>3;return aaa;}

const int N=1e5+5;

struct node;typedef node* ptr;

struct node{

	ptr lc,rc;int v,sz;unsigned int pr;

	inline node();

	inline void init(R int val){v=val,pr=rd(),sz=1;}

	inline ptr upd(){return sz=lc->sz+rc->sz+1,this;}

}e[N],*rt=e;int tot;

inline node::node(){lc=rc=e;}

inline ptr newnode(R int v){return e[++tot].init(v),e+tot;}

void split(ptr p,int k,ptr &s,ptr &t){

	if(p==e)return s=t=e,void();

	if(p->v<=k)s=p,split(p->rc,k,p->rc,t);

		else t=p,split(p->lc,k,s,p->lc);

	p->upd();

}

ptr merge(ptr s,ptr t){

	if(s==e)return t;if(t==e)return s;

	if(s->pr<t->pr)return s->rc=merge(s->rc,t),s->upd();

	return t->lc=merge(s,t->lc),t->upd();

}

void insert(int k){

	ptr s,t;

	split(rt,k,s,t);

	rt=merge(merge(s,newnode(k)),t);

}

void erase(int k){

	ptr s,t,p;

	split(rt,k,s,t),split(s,k-1,s,p),p=merge(p->lc,p->rc);

	rt=merge(merge(s,p),t);

}

int rk(int k){

	ptr s,t;int now;

	split(rt,k-1,s,t);now=s->sz+1;

	return rt=merge(s,t),now;

}

int Kth(ptr p,int k){

	if(p->lc->sz==k-1)return p->v;

	if(p->lc->sz>=k)return Kth(p->lc,k);

	return Kth(p->rc,k-p->lc->sz-1);

}

int Pre(int k){

	ptr s,t;int now;

	split(rt,k-1,s,t),now=Kth(s,s->sz);

	return rt=merge(s,t),now;

}

int nxt(int k){

	ptr s,t;int now;

	split(rt,k,s,t),now=Kth(t,1);

	return rt=merge(s,t),now;

}

int main(){

//	freopen("testdata.in","r",stdin);

	int q=read(),op,x;

	while(q--){

		op=read(),x=read();

		switch(op){

			case 1:insert(x);break;

			case 2:erase(x);break;

			case 3:print(rk(x));break;

			case 4:print(Kth(rt,x));break;

			case 5:print(Pre(x));break;

			case 6:print(nxt(x));break;

		}

	}

	return Ot(),0;

}