【luogu P3369 普通平衡树（Treap/SBT）】 模板 Splay

题目链接：https://www.luogu.org/problemnew/show/P3369

#include <cstdio>
#include <algorithm>
#include <iostream>
#define ri register
#define il inline
using namespace std;
const int maxn = 1000000;
struct RNG{
    int fa, cnt, v, sub, son[2];
}e[maxn];
int root, n, m, whole_size;
il void Clear(int x){
    e[x].cnt = e[x].fa = e[x].son[0] = e[x].son[1] = e[x].sub = e[x].v = 0;
}
il bool Get_which(int x){
    return e[e[x].fa].son[1] == x;
}
il void update(int x){
    if(x){
        e[x].sub = e[x].cnt;
        if(e[x].son[0]) e[x].sub += e[e[x].son[0]].sub;
        if(e[x].son[1]) e[x].sub += e[e[x].son[1]].sub;
    }
    return;
}
il void rotate(int x){
    int father = e[x].fa, get_father = e[father].fa, which_son = Get_which(x);
    e[father].son[which_son] = e[x].son[which_son^1];
    e[e[father].son[which_son]].fa = father;
    e[x].son[which_son^1] = father;
    e[father].fa = x;
    e[x].fa = get_father;
    if(get_father){
        e[get_father].son[e[get_father].son[1]==father] = x;
    }
    update(father);
    update(x);
    return;
}
il void splay(int x){
    for(int fa; fa = e[x].fa; rotate(x))
    if(e[fa].fa)
        rotate((Get_which(x) == Get_which(fa)) ? fa : x);
    root = x;
    return;
}
il void insert(int x){
    if(!root){
        whole_size++;
        e[whole_size].son[0] = e[whole_size].son[1] = e[whole_size].fa = 0;
        root = whole_size;
        e[whole_size].sub = e[whole_size].cnt++;
        e[whole_size].v = x;
        return;
    }
    int now = root, fa = 0;
    while(1)
    {
        if(x == e[now].v){
            e[now].cnt++;
            update(now);
            update(fa);
            splay(now);
            break;
        }
        fa = now;
        now = e[now].son[e[now].v < x];
        if(!now){
            whole_size++;
            e[whole_size].son[0] = e[whole_size].son[1] = 0;
            e[whole_size].fa = fa;
            e[whole_size].sub = e[whole_size].cnt = 1;
            e[fa].son[e[fa].v<x] = whole_size;
            e[whole_size].v = x;
            update(fa);
            splay(whole_size);
            break;
        }
    }
    return;
}
il int Find_num(int x){
    int now = root;
    while(1){
        if(e[now].son[0]&&x<=e[e[now].son[0]].sub)
            now = e[now].son[0];
        else{
            int temp = (e[now].son[0]?e[e[now].son[0]].sub:0)+e[now].cnt;
            if(x <= temp) return e[now].v;
            x-=temp;
            now = e[now].son[1];
        }
    }
}
il int Find_rank(int x){
	int now = root, ans = 0;
	while(1){
		if(x<e[now].v)
			now = e[now].son[0];
		else{
			ans += (e[now].son[0]?e[e[now].son[0]].sub:0);
			if(x == e[now].v){
				splay(now); return ans+1;
			}
		ans += e[now].cnt;
		now = e[now].son[1];	
		}
	}
}
il int Find_pre(){
	int now = e[root].son[0];
	while(e[now].son[1]) now = e[now].son[1];
	return now;
}
il int Find_suffix(){
	int now = e[root].son[1];
	while(e[now].son[0]) now = e[now].son[0];
	return now;
}
il void Delete(int x)
{
	int hhh = Find_rank(x);
	if(e[root].cnt>1){
		e[root].cnt--;
		update(root);
		return;
	}
	if(!e[root].son[0]&&!e[root].son[1]){
		Clear(root);
		root = 0;
		return;
	}
	if(!e[root].son[0]){
		int old_root = root;
		root = e[root].son[1];
		e[root].fa = 0;
		Clear(old_root);
		return;
	}
	else if(!e[root].son[1]){
		int old_root = root;
		root = e[root].son[0];
		e[root].fa = 0;
		Clear(old_root);
		return;
	}
	int left_max = Find_pre(), old_root = root;
	splay(left_max);
	e[root].son[1] = e[old_root].son[1];
	e[e[old_root].son[1]].fa = root;
	Clear(old_root);
	update(root);
	return ;
}
int main(){
	int m, num, be_dealt;
	scanf("%d",&m);
	for(int i = 1; i <= m; i++){
		scanf("%d%d",&num,&be_dealt);
		if(num == 1){insert(be_dealt);}
		if(num == 2){Delete(be_dealt);}
		if(num == 3){printf("%d
",Find_rank(be_dealt));}
		if(num == 4){printf("%d
",Find_num(be_dealt));}
		if(num == 5){
			insert(be_dealt);
			printf("%d
",e[Find_pre()].v);
			Delete(be_dealt);}
		if(num == 6){
			insert(be_dealt);
			printf("%d
",e[Find_suffix()].v);
			Delete(be_dealt);
		}
	}
	return 0;
}