「Splay」普通平衡树模板

口诀：

$rotate$：先上再下，最后自己

$splay$：祖父未到旋两次，三点一线旋父亲，三点折线旋自己。

$delete$：没有儿子就删光。单个儿子删自己。两个儿子找前驱。

易错点：

$rotate$：祖父不在自己做根

$delete$：自己做根父亲为0

$kth$：先减排名后转移

/*By DennyQi 2018*/
#include <cstdio>
#include <queue>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long ll;
const int MAXN = ;
const int INF = 0x3f3f3f3f;
inline int Max(const int a, const int b){ return (a > b) ? a : b; }
inline int Min(const int a, const int b){ return (a < b) ? a : b; }
inline int read(){
    int x = ; int w = ; register char c = getchar();
    for(; c ^ '-' && (c < '' || c > ''); c = getchar());
    if(c == '-') w = -, c = getchar();
    for(; c >= '' && c <= ''; c = getchar()) x = (x<<) + (x<<) + c - ''; return x * w;
}
int n,opt,x,num_node;
int ch[MAXN][],fa[MAXN],val[MAXN],size[MAXN],cnt[MAXN],root;
struct Splay{
    inline bool rson(int f, int x){
        return ch[f][] == x;
    }
    inline void update(int x){
        size[x] = size[ch[x][]] + size[ch[x][]] + cnt[x];
    }
    inline void clear(int x){
        val[x]=cnt[x]=size[x]=fa[x]=ch[x][]=ch[x][]=;
    }
    inline void rotate(int x){
        int f = fa[x], gf = fa[f];
        bool p = rson(f, x), q = !p;
        if(gf) ch[gf][rson(gf,f)] = x; else root = x; fa[x] = gf;
        ch[f][p] = ch[x][q], fa[ch[x][q]] = f;
        ch[x][q] = f, fa[f] = x;
        update(f), update(x);
    }
    inline void splay(int x, int target){
        while(fa[x] != target){
            int f = fa[x], gf = fa[f];
            if(gf == target){ rotate(x); break;}
            if(rson(gf,f) == rson(f,x)) rotate(f); else rotate(x);
            rotate(x);
        }
    }
    inline void Insert(int v){
        int o = root;
        if(root == ){
            root = ++num_node;
            cnt[root] = size[root] = ;
            val[root] = v;
            return;
        }
        for(;o;){
            if(v == val[o]){
                cnt[o]++, size[o]++;
                splay(o, );
                return;
            }
            bool b = v>val[o];
            if(!ch[o][b]){
                ch[o][b] = ++num_node;
                cnt[ch[o][b]] = size[ch[o][b]] = ;
                val[ch[o][b]] = v, fa[ch[o][b]] = o;
                splay(ch[o][b], );
                return;
            }
            o = ch[o][v>val[o]];
        }
    }
    inline void Find(int v){
        for(int o = root; o; o = ch[o][v>val[o]]){
            if(val[o] == v){ splay(o, ); return; }
            if(!ch[o][v>val[o]]) return;
        }
    }
    inline void Delete(int v){
        Find(v);
        if(val[root] != v) return;
        int o = root;
        if(cnt[o] > ){ --cnt[o],--size[o]; return; }
        if(!ch[o][] && !ch[o][]){ root = , fa[root] = ; return; }
        if(!ch[o][]){ root = ch[o][], fa[root] = ; return; }
        if(!ch[o][]){ root = ch[o][], fa[root] = ; return; }
        int l_max = ch[root][];
        while(ch[l_max][]) l_max = ch[l_max][];
        splay(l_max, root);
        ch[l_max][] = ch[root][];
        fa[ch[root][]] = l_max;
        fa[l_max] = ;
        int pre_root = root;
        root = l_max;
        clear(pre_root);
    }
    inline int Rnk(int x){
        Find(x);
        return size[ch[root][]] + ;
    }
    inline int Kth(int k){
        for(int o = root; o;){
            if(size[ch[o][]] >= k) o = ch[o][];
            else if(size[ch[o][]] + cnt[o] < k){
                k -= size[ch[o][]] + cnt[o];
                o = ch[o][];
            }
            else{
                splay(o,);
                return val[o];
            }
        }
    }
    inline int Pre(int v){
        Insert(v);
        int o = ch[root][];
        while(ch[o][]) o = ch[o][];
        int ans = val[o];
        Delete(v);
        return ans;
    }
    inline int Nxt(int v){
        Insert(v);
        int o = ch[root][];
        while(ch[o][]) o = ch[o][];
        int ans = val[o];
        Delete(v);
        return ans;
    }
}qxz;
int main(){
//    freopen(".in","r",stdin);
    n = read();
    for(int i = ; i <= n; ++i){
        opt = read(), x = read();
        if(opt==) qxz.Insert(x);
        if(opt==) qxz.Delete(x);
        if(opt==) printf("%d\n",qxz.Rnk(x));
        if(opt==) printf("%d\n",qxz.Kth(x));
        if(opt==) printf("%d\n",qxz.Pre(x));
        if(opt==) printf("%d\n",qxz.Nxt(x));
    }
    return ;
}