传送门

就是普通平衡树，可以拿来练非旋treap" role="presentation" style="position: relative;">treaptreap的板子。

贴个代码：

#include<bits/stdc++.h>
#define N 300005
using namespace std;
typedef pair<int,int> res;
int n;
inline int read(){
    int ans=0;
    char ch=getchar();
    while(!isdigit(ch))ch=getchar();
    while(isdigit(ch))ans=(ans<<3)+(ans<<1)+(ch^48),ch=getchar();
    return ans;
}
struct Treap{
    int son[N][2],root,cnt,siz[N],rd[N],val[N];
    inline int build(int v){siz[++cnt]=1,val[cnt]=v,rd[cnt]=rand(),son[cnt][0]=son[cnt][1]=0;return cnt;}
    inline void pushup(int p){siz[p]=siz[son[p][0]]+siz[son[p][1]]+1;}
    inline int merge(int a,int b){
        if(!a||!b)return a+b;
        if(rd[a]<rd[b]){son[a][1]=merge(son[a][1],b),pushup(a);return a;}
        son[b][0]=merge(a,son[b][0]),pushup(b);return b;
    }
    inline res split(int p,int k){
        if(!p)return res(0,0);
        res tmp,ans;
        if(siz[son[p][0]]>=k){tmp=split(son[p][0],k),son[p][0]=tmp.second,pushup(p),ans.first=tmp.first,ans.second=p;return ans;}
        tmp=split(son[p][1],k-siz[son[p][0]]-1),son[p][1]=tmp.first,pushup(p),ans.first=p,ans.second=tmp.second;return ans;
    }
    inline int rank(int p,int v){
        if(!p)return 0;
        if(val[p]>v)return rank(son[p][0],v);
        return rank(son[p][1],v)+siz[son[p][0]]+1;
    }
    inline int kth(int k){
        res x=split(root,k),y=split(x.first,k-1);
        root=merge(merge(y.first,y.second),x.second);
        return val[y.second];
    }
    inline int find(int p,int v){
        if(!p)return 0;
        if(val[p]>=v)return find(son[p][0],v);
        return find(son[p][1],v)+siz[son[p][0]]+1;
    }
    inline void ins(int v){
        int k=rank(root,v);
        res x=split(root,k);
        int p=build(v);
        root=merge(merge(x.first,p),x.second);
    }
    inline void del(int v){
        int k=rank(root,v);
        res x=split(root,k);
        root=merge(split(x.first,k-1).first,x.second);
    }
    inline int pre(int p,int v){
        if(!p)return -0x3f3f3f3f;
        if(val[p]<v)return max(val[p],pre(son[p][1],v));
        return pre(son[p][0],v);
    }
    inline int suf(int p,int v){
        if(!p)return 0x3f3f3f3f;
        if(val[p]>v)return min(val[p],suf(son[p][0],v));
        return suf(son[p][1],v);
    }
}T;
int main(){
    srand(time(NULL));
    n=read();
    while(n--){
        int op=read(),x=read();
        switch(op){
            case 0:{T.ins(x);break;}
            case 1:{T.del(x);break;}
            case 2:{printf("%d\n",T.kth(x));break;}
            case 3:{printf("%d\n",T.find(T.root,x));break;}
            case 4:{int tmp=T.pre(T.root,x);printf("%d\n",tmp==-0x3f3f3f3f?-1:tmp);break;}
            default:{int tmp=T.suf(T.root,x);printf("%d\n",tmp==0x3f3f3f3f?-1:tmp);break;}
        }
    }
    return 0;
}