Treap

 粗略的试了一下，大概是没有问题的

#include<cstdio>

#include<cstring>

#include<time.h>

#include<stdlib.h>

#define random(x) (rand()%x)

#define maxn 100007

using namespace std;

int fa[maxn],son[maxn][2],siz[maxn],priority[maxn],weight[maxn],root=0,counter=0;

void clear()

{

srand((int)time(0));//这里不用每次更新

memset(fa,0,sizeof(int));

memset(son,0,sizeof(int));

memset(siz,0,sizeof(int));

memset(priority,0,sizeof(int));

memset(weight,0,sizeof(int));

}

inline int getpri()

{

return random(100);//太大好像不行诶

}

inline int getpos(int now,int val)

{

if(weight[now]>val&&son[now][0])return getpos(son[now][0],val);//注意判断是否为空

if(weight[now]<val&&son[now][1])return getpos(son[now][1],val);

return now;

}

inline int askflag(int now)

{if(son[fa[now]][0]==now)return 0;return 1;}

inline void updata(int now)

{siz[now]=1+siz[son[now][0]]+siz[son[now][1]];} 

inline void rorate(int now)

{

int f=fa[now],flag=askflag(now);

if(root==f){root=now;fa[now]=-1;}

else {son[fa[f]][askflag(f)]=now;fa[now]=fa[f];}

if(son[now][!flag])fa[son[now][!flag]]=f;

son[f][flag]=son[now][!flag];

fa[f]=now;

son[now][!flag]=f;

updata(f);updata(now);

}

inline void tenance(int now)

{

while(priority[fa[now]]>priority[now])//居然比splay好写

rorate(now);

}

inline int rank(int now,int x)

{

if(weight[now]<weight[x])return 1+siz[son[now][0]]+rank(son[now][1],x);

if(weight[now]==weight[x])return 1+siz[son[now][0]];

if(weight[now]>weight[x])return rank(son[now][0],x);

}

inline int Kth(int now,int k)

{

if(siz[son[now][0]]+1==k)return now;

if(siz[son[now][0]]+1>k)return Kth(son[now][0],k);

if(siz[son[now][0]]+1<k)return Kth(son[now][1],k-1-siz[son[now][0]]);

}

inline void insert(int val)

{

if(!root)

{

fa[root=++counter]=-1;

weight[counter]=val;

updata(counter);

}

else 

{

int pos=getpos(root,val);

fa[++counter]=pos;

weight[counter]=val;//之前居然忘记赋值了

if(weight[pos]>val)son[pos][0]=counter;

if(weight[pos]<val)son[pos][1]=counter;

updata(counter),updata(pos);

}

priority[counter]=getpri();

tenance(counter);

}

int main()

{

int n,m,temp;

char ss[10],c;

scanf("%d%d",&n,&m);

for(int i=1;i<=n;i++)

{

scanf("%d",&temp);

insert(temp);

}

for(int i=1;i<=m;i++)

{

scanf("%s",ss);

scanf("%d",&temp);

c=ss[0];

if(c=='R')printf("%d\n",rank(root,temp));

if(c=='K')printf("%d",weight[Kth(root,temp)]); 

}

return 0;

}