HDU 4006 求第k大数 treap

裸题，瞬秒。。

#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <math.h>
#include <vector>
#include <set>
#include <map>
#include <queue>
using namespace std;
#define L(id) tree[id].ch[0]
#define R(id) tree[id].ch[1]
#define Size(id) tree[id].size
#define Father(id) tree[id].fa
#define Val(id) tree[id].val
#define ll int
ll Mid(ll x,ll y){return (x+y)>>1;}
#define N 30100

ll a[N],n;
int ch[N][2],val[N],counts[N],r[N],size[N],tot,root;
int Newnode(int &rt,int v)
{
	rt=++tot;
	val[rt]=v;
	ch[rt][0]=ch[rt][1]=0;
	counts[rt]=size[rt]=1;
	r[rt]=rand();
	return rt;
}
inline void PushUp(int rt)
{
	size[rt]=size[ch[rt][0]]+size[ch[rt][1]]+counts[rt];
}
void Rotate(int &x,int kind)
{
	int y=ch[x][kind^1];
	ch[x][kind^1]=ch[y][kind];
	ch[y][kind]=x;
	PushUp(x);PushUp(y);
	x=y;
}
int Insert(int &rt,int v)
{
	if(rt==0)
		return Newnode(rt,v);
	int ans;
	if(v==val[rt]) counts[rt]++,ans = rt;
	else
	{
		int kind=(v>val[rt]);
		ans = Insert(ch[rt][kind],v);
		if(r[ch[rt][kind]]<r[rt])
			Rotate(rt,kind^1);
	}
	PushUp(rt);
	return ans;
}
int select(int rt,int k)
{
	if(size[ch[rt][0]]>=k) return select(ch[rt][0],k);
	if(size[ch[rt][0]]+counts[rt]>=k) return val[rt];
	return select(ch[rt][1],k-size[ch[rt][0]]-counts[rt]);
}
void remove(int &rt,int v)
{
	if(val[rt]==v)
	{
		if(counts[rt]>1)
			counts[rt]--;
		else if(!ch[rt][0]&&!ch[rt][1])
		{rt=0;return ;}
		else
		{
			int kind=r[ch[rt][0]]<r[ch[rt][1]];
			Rotate(rt,kind);
			remove(rt,v);
		}
	}
	else remove(ch[rt][v>val[rt]],v);
	PushUp(rt);
}
void Init()
{
	ch[0][0]=ch[0][1]=0;
	size[0]=counts[0]=val[0]=0;
	tot=root=0;
	r[0]=(1LL<<31)-1;
	Newnode(root,2000000001);
}
int q[N];
char s[2];
int main(){
	int que,i,j,k,l,r;
	while(~scanf("%d %d",&n,&que)){
		Init();
		while(n--){
			scanf("%s",s);
			if(s[0]=='I')scanf("%d",&l),Insert(root,-l);
			else printf("%dn",-select(root,que));
		}
	}
	return 0;
}