Splay模板

/****************************
* Author : W.A.R            *
* Date : 2020-09-15-18:42   *
****************************/
/*
*/

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<iostream>
#include<algorithm>
#include<queue>
#include<map>
#include<stack>
#include<string>
#include<set>
#define show(x) std:: cerr << #x << " = " << x << std::endl;
#define mem(a,x) memset(a,x,sizeof(a))
#define Rint register int
using namespace std;
typedef long long ll;
const int maxn=1e6+10;
const int maxm=2e6+10;
const ll mod=1e9+7;


int son[maxn][2],f[maxn],key[maxn],cou[maxn],siz[maxn],root,sz;

void clear(int x){son[x][0]=son[x][1]=cou[x]=f[x]=siz[x]=key[x]=0;}
bool  get(int x){return son[f[x]][1]==x;}
void update(int x){
	if(x){
		siz[x]=cou[x];
		if(son[x][0])siz[x]+=siz[son[x][0]];
		if(son[x][1])siz[x]+=siz[son[x][1]];
	}
}
void rotate(int x){
	int old=f[x],oldf=f[old],whichson=get(x);
	son[old][whichson]=son[x][whichson^1],f[son[old][whichson]]=old;
	son[x][whichson^1]=old,f[old]=x;
	f[x]=oldf;
	if(oldf)son[oldf][son[oldf][1]==old]=x;
	update(old);
	update(x);
}
//void splay(int x,int goal){
//	for(int fa;(fa=f[x])!=goal;rotate(x)){
//		if(f[fa]!=goal)rotate((get(x)==get(fa))?fa:x);
//	}
//	if(!goal)root=x;
//}
void splay(int x){
	for(int fa;(fa=f[x]);rotate(x))if(f[fa])rotate((get(x)==get(fa))?fa:x);
	root=x;
}
void insert(int x){
	if(!root){
		sz++;
		son[sz][0]=son[sz][1]=f[sz]=0;
		key[sz]=x;
		cou[sz]=siz[sz]=1;
		root=sz;
		return;
	}
	int now=root,fa=0;
	while(1){
		if(x==key[now]){
			cou[now]++;
			update(now);
			update(fa);
			splay(now);
			break;
		}
		fa=now;
		now=son[now][key[now]<x];
		if(!now)
		{
			sz++;
			f[sz]=fa;
			son[sz][0]=son[sz][1]=0;
			cou[sz]=siz[sz]=1;
			son[fa][key[fa]<x]=sz;
			key[sz]=x;
			update(fa);
			splay(sz);
			break;
		}
	}
}
int find(int x){
	int now=root,ans=0;
	while(1){
		if(x<key[now])now=son[now][0];
		else {
			ans+=(son[now][0]?siz[son[now][0]]:0);
			if(x==key[now]){splay(now);return ans+1;}
			ans+=cou[now];
			now=son[now][1];
		}
	}
}
int findx(int x){
	int now=root;
	while(1){
		if(son[now][0]&&x<=siz[son[now][0]])now=son[now][0];
		else{
			int tmp=(son[now][0]?siz[son[now][0]]:0)+cou[now];
			if(x<=tmp)return key[now];
			x-=tmp;
			now=son[now][1];
		}
	}
}
int pre(){
	int now=son[root][0];
	while(son[now][1])now=son[now][1];return now;
}
int nxt(){
	int now=son[root][1];
	while(son[now][0])now=son[now][0];return now;
}
void del(int x){
	int whatever=find(x);
	if(cou[root]>1){
		cou[root]--;
		update(root);
		return;
	}
	if(!son[root][0]&&!son[root][1]){clear(root);root=0;return;}
	if(!son[root][0]){
		int oldroot=root;
		root=son[root][1];
		f[root]=0;
		clear(oldroot);
		return;
	}
	int leftbig=pre(),oldroot=root;
	splay(leftbig);
	son[root][1]=son[oldroot][1];
	f[son[root][1]]=root;
	clear(oldroot);
	update(root);
	return;
}
int main(){
	int n;scanf("%d",&n);
	for(int i=1;i<=n;i++)
	{
		int op,x;
		scanf("%d%d",&op,&x);
		if(op==1)insert(x);
		else if(op==2)del(x);
		else if(op==3)printf("%d\n",find(x));
		else if(op==4)printf("%d\n",findx(x));
		else if(op==5)insert(x),printf("%d\n",key[pre()]),del(x);
		else if(op==6)insert(x),printf("%d\n",key[nxt()]),del(x);
	}
	return 0;
}


//https://blog.csdn.net/wpx18182323/article/details/81668874