题面

题解

写了一下\(FHQ\ Treap\)

//minamoto#include
    
     #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 go(u) for(int i=head[u],v=e[i].v;i;i=e[i].nx,v=e[i].v)template
      
       inline bool cmax(T&a,const T&b){return a
       
        
         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
         
          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;}