【bzoj3224】 Tyvj1728—普通平衡树

// bzoj3224
#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<cmath>
#define LL long long
#define inf 2147483640
#define Pi acos(-1.0)
#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout)
using namespace std;

const int maxn=100010;
int n,sz,Dargen;
struct node {
	int son[2],size,val,rnd,w;
	int& operator [] (int x) {return son[x];}
}tr[maxn];

void pushup(int k) {
	tr[k].size=tr[tr[k][0]].size+tr[tr[k][1]].size+tr[k].w;
}
void rotate(int &x,int p) {  //记得&
	int y=tr[x][p];
	tr[x][p]=tr[y][p^1];tr[y][p^1]=x;x=y; //记得写x=y
	pushup(tr[y][p^1]);pushup(y);
}
void insert(int &k,int x) {
	if (!k) {tr[k=++sz].val=x;tr[k].rnd=rand();tr[k].size=tr[k].w=1;return;}
	int p=x>tr[k].val;tr[k].size++;
	if (tr[k].val==x) {tr[k].w++;return;}
	insert(tr[k][p],x);
	if (tr[tr[k][p]].rnd>tr[k].rnd) rotate(k,p);
}
void erase(int &k,int x) {
	if (k==0) return;
	if (tr[k].val==x) {
		if (tr[k].w>1) {tr[k].w--;tr[k].size--;return;}
		if (tr[k][0]*tr[k][1]==0) k=tr[k][0]+tr[k][1];
		else rotate(k,tr[tr[k][0]].rnd<tr[tr[k][1]].rnd),erase(k,x);
	}
	else if (x<tr[k].val) tr[k].size--,erase(tr[k][0],x);
	else tr[k].size--,erase(tr[k][1],x);
}
int find(int k,int x) {
	if (!k) return 0;
	if (tr[tr[k][0]].size<x && x<=tr[tr[k][0]].size+tr[k].w) return tr[k].val;
	else if (x<=tr[tr[k][0]].size) return find(tr[k][0],x);
	else return find(tr[k][1],x-tr[tr[k][0]].size-tr[k].w);
}
int rank(int k,int x) {
	if (!k) return 0;
	if (tr[k].val==x) return tr[tr[k][0]].size+1;
	if (x<=tr[k].val) return rank(tr[k][0],x);
	else return rank(tr[k][1],x)+tr[tr[k][0]].size+tr[k].w;
}
int main() {
	scanf("%d",&n);
	for (int op,x,i=1;i<=n;i++) {
		scanf("%d%d",&op,&x);
		if (op==1) insert(Dargen,x);
		if (op==2) erase(Dargen,x);
		if (op==3) printf("%d\n",rank(Dargen,x));
		if (op==4) printf("%d\n",find(Dargen,x));
		if (op==5) printf("%d\n",find(Dargen,rank(Dargen,x-1)));
		if (op==6) {
			if (find(Dargen,rank(Dargen,x+1))==x+1) printf("%d\n",x+1);
			else printf("%d\n",find(Dargen,rank(Dargen,x+1)+1));
		}
	}
	return 0;
}