fhq treap ------ luogu P3369 【模板】普通平衡树（Treap/SBT）

二次联通门 : LibreOJ #104. 普通平衡树

#include <cstdio>
#include <iostream>
#include <algorithm>
const int BUF = ;
char Buf[BUF], *buf = Buf;

inline void read (int &now)
{
    bool temp = false;
    for (now = ; !isdigit (*buf); ++ buf)
        if (*buf == '-') temp = true;
    for (; isdigit (*buf); now = now * + *buf - '', ++ buf);
    if (temp) now = -now;
}

struct T_D
{
    T_D *L, *R;
    int key, r, s;
    inline void Updata ()
    {
        s =  + (L ? L->s : ) + (R ? R->s : );
    }
};

#define Max 1231231
struct D
{
    T_D *x, *y; D () {}
    D (T_D *_x, T_D *_y) : x (_x), y (_y) {}
};
class Fhq_Treap
{
    private :

        T_D poor[Max], *Ta, *Root;

        inline T_D *New (int _x)
        {
            T_D *now = ++ Ta;
            now->r = rand (), now->key = _x;
            now->s = , now->L = now->R = NULL;
            return now;
        }

        D Split (T_D *now, int k)
        {
            if (now == NULL) return D (NULL, NULL);
            D res;
            if ((now->L ? now->L->s : ) >= k)
            {
                res = Split (now->L, k);
                now->L = res.y, now->Updata ();
                res.y = now;
            }
            else
            {
                res = Split (now->R, k - (now->L ? now->L->s : ) - );
                now->R = res.x, now->Updata ();
                res.x = now;
            }
            return res;
        }

        T_D *Merge (T_D *A, T_D *B)
        {
            if (A == NULL) return B;
            if (B == NULL) return A;
            if (A->r < B->r)
            {
                A->R = Merge (A->R, B);
                A->Updata (); return A;
            }
            else
            {
                B->L = Merge (A, B->L);
                B->Updata (); return B;
            }
        }

        int Get_rank (T_D *now, int k)
        {
            if (now == NULL) return ;
            return k <= now->key ? Get_rank (now->L, k) : (Get_rank (now->R, k) + (now->L ? now->L->s : ) + );
        }

    public :

        Fhq_Treap () { Ta = poor; }
        inline int Get_rank (int k)
        {
            return Get_rank (Root, k) + ;
        }

        int Find_kth (int k)
        {
            D x = Split (Root, k - );
            D y = Split (x.y, );
            T_D *res = y.x;
            Root = Merge (Merge (x.x, res), y.y);
            return res->key;
        }

        void Insert (int key)
        {
            int k = Get_rank (Root, key);
            D x = Split (Root, k);
            T_D *now = New (key);
            Root = Merge (Merge (x.x, now), x.y);
        }

        void Delete (int key)
        {
            int k = Get_rank (Root, key);
            D x = Split (Root, k);
            D y = Split (x.y, );
            Root = Merge (x.x, y.y);
        }

        int Find_Pre (int key)
        {
            int k = Get_rank (Root, key);
            D x = Split (Root, k - );
            D y = Split (x.y, );
            T_D *res = y.x;
            Root = Merge (Merge (x.x, res), y.y);
            return res->key;
        }

        int Find_Suc (int key)
        {
            int k = Get_rank (Root, key + );
            D x = Split (Root, k);
            D y = Split (x.y, );
            T_D *res = y.x;
            Root = Merge (Merge (x.x, res),  y.y);
            return res->key;
        }
};

Fhq_Treap Tree;
int Main ()
{
    fread (buf, , BUF, stdin);
    int N, M; register int i;
    read (N); int x, type;
    for (i = ; i <= N; ++ i)
    {
        read (type), read (x);
         if (type == )
            Tree.Insert (x);
        else if (type == )
            Tree.Delete (x);
        else if (type == )
            printf ("%d\n", Tree.Get_rank (x));
        else if (type == )
            printf ("%d\n", Tree.Find_kth (x));
        else if (type == )
            printf ("%d\n", Tree.Find_Pre (x));
        else printf ("%d\n", Tree.Find_Suc (x));
    }
    return ;
}

int ZlycerQan = Main ();
int main (int argc, char *argv[]) {;}