FHQ Treap 板子

#include<cstdio>
#include<algorithm>
#include<ctime>
using namespace std;
int n,tot = 0;

struct tree{
	int siz,ls,rs,v,rnd;
}tr[100005];
int add(int val)
{
	tr[++tot] = (tree){1,0,0,val,rand()};
	return tot;
}
void update(int x){tr[x].siz = tr[tr[x].ls].siz + tr[tr[x].rs].siz + 1;}
void split(int rt,int &a,int &b,int val)
{
	if (rt == 0) return void(a = b = 0);
	if (tr[rt].v <= val) a = rt,split(tr[rt].rs,tr[a].rs,b,val);
	else b = rt,split(tr[rt].ls,a,tr[b].ls,val);
	update(rt);
}
void merge(int &rt,int a,int b)
{
	if (a == 0 || b == 0) return void(rt = a + b);
	if (tr[a].rnd < tr[b].rnd) rt = a,merge(tr[rt].rs,tr[a].rs,b);
	else rt = b,merge(tr[rt].ls,a,tr[b].ls);
	update(rt);
}
void Insert(int &rt,int val)
{
	int x = 0,y = 0,k = add(val);
	split(rt,x,y,val);
	merge(x,x,k),merge(rt,x,y);
}
void Delete(int &rt,int val)
{
	int x = 0,y = 0,z = 0;
	split(rt,x,y,val),split(x,x,z,val - 1);
	merge(z,tr[z].ls,tr[z].rs),merge(x,x,z),merge(rt,x,y);
}
int getkth(int rt,int k)
{
	while (tr[tr[rt].ls].siz + 1 != k) 
		if (tr[tr[rt].ls].siz >= k) rt = tr[rt].ls;
		else k -= tr[tr[rt].ls].siz + 1,rt = tr[rt].rs;
	return tr[rt].v;
}
int getrnk(int &rt,int val)
{
	int x = 0,y = 0,tmp;
	split(rt,x,y,val - 1);
	tmp = tr[x].siz + 1;
	merge(rt,x,y);
	return tmp;
}
int getpre(int &rt,int val)
{
	int x = 0,y = 0,tmp;
	split(rt,x,y,val - 1);
	tmp = getkth(x,tr[x].siz);
	merge(rt,x,y);
	return tmp;
}
int getscc(int &rt,int val)
{
	int x = 0,y = 0,tmp;
	split(rt,x,y,val);
	tmp = getkth(y,1);
	merge(rt,x,y);
	return tmp;
}
int main()
{
	srand(time(NULL));
	scanf("%d",&n); 
	int root = 0;
	for (int i = 1,q,p; i <= n; i++)
	{
		scanf("%d%d",&q,&p);
		if (q == 1) Insert(root,p);
		if (q == 2) Delete(root,p);
		if (q == 3) printf("%d
",getrnk(root,p));
		if (q == 4) printf("%d
",getkth(root,p));
		if (q == 5) printf("%d
",getpre(root,p));
		if (q == 6) printf("%d
",getscc(root,p));
	}
}