普通平衡树 - Treap

怕被学弟怼 : "你的博客上没有Treap模板啊?"

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long ll;
inline void read(int &x){
	x=0;char ch;bool flag = false;
	while(ch=getchar(),ch<'!');if(ch == '-') ch=getchar(),flag = true;
	while(x=10*x+ch-'0',ch=getchar(),ch>'!');if(flag) x=-x;
}
inline int cat_max(const int &a,const int &b){return a>b ? a:b;}
inline int cat_min(const int &a,const int &b){return a<b ? a:b;}
const int maxn = 200010;
struct Node{
	Node *ch[2];
	int siz,w,fix;
	void update(){
		siz = ch[0]->siz + ch[1]->siz + 1;
	}
};
struct Treap{
	Node mem[maxn];
	Node *tail,*root,*null;
	Node *bc[maxn];int top;
	Treap(){
		tail = mem;null = tail++;
		null->ch[0] = null->ch[1] = null;
		null->siz = null->w = 0;null->fix = 0x7f7f7f7f;
		root = null;
	}
	Node* newNode(int key){
		Node *p = top ? bc[top--] : tail++;
		p->ch[0] = p->ch[1] = null;
		p->siz = 1;p->w = key;p->fix = rand();
		return p;
	}
	void del(Node* &p){
		bc[++top] = p;
		p = null;
	}
	void turn(Node* &p,int k){
		Node *y = p->ch[k^1];
		p->ch[k^1] = y->ch[k];
		y->ch[k] = p;
		y->siz = p->siz;
		p->update();p = y;
	}
	int val;
	void Insert(Node* &p){
		if(p == null){
			p = newNode(val);
			return;
		}
		p->siz++;
		Insert(p->ch[val >= p->w]);
		if(p->ch[val >= p->w]->fix < p->fix)
			turn(p,val < p->w);
	}
	void Insert(int x){
		val = x;
		Insert(root);
	}
	void Erase(Node* &p){
		if(val == p->w){
			if(p->ch[0] != null && p->ch[1] != null){
				int k = p->ch[0]->fix >= p->ch[1]->fix;
				turn(p,k);
				Erase(p->ch[k]);
			}else{
				Node *y = p->ch[0] == null ? p->ch[1] : p->ch[0];
				del(p);p = y;
			}
		}else Erase(p->ch[val >= p->w]);
		if(p != null) p->update();
	}
	void Erase(int x){
		val = x;
		Erase(root);
	}
	int Kth(int k){
		Node *nw = root;
		while(nw != null){
			if(nw->ch[0]->siz + 1 == k) return nw->w;
			if(nw->ch[0]->siz + 1 >  k) nw = nw->ch[0];
			else k -= nw->ch[0]->siz + 1,nw = nw->ch[1];
		}
	}
	int rank(int x){
		int ret = 1;
		Node *nw = root;
		while(nw != null){
			if(x <= nw->w) nw = nw->ch[0];
			else{
				ret += nw->ch[0]->siz + 1;
				nw = nw->ch[1];
			}
		}return ret;
	}
}*zs = new Treap();
int main(){
	srand(666);
	int n;read(n);
	int opt,x;
	while(n--){
		read(opt);read(x);
		switch(opt){
			case 1:
				zs->Insert(x);
				break;
			case 2:
				zs->Erase(x);
				break;
			case 3:
				printf("%d\n",zs->rank(x));
				break;
			case 4:
				printf("%d\n",zs->Kth(x));
				break;
			case 5:
				printf("%d\n",zs->Kth(zs->rank(x)-1));
				break;
			case 6:
				printf("%d\n",zs->Kth(zs->rank(x+1)));
				break;
 
		}
	}
	getchar();getchar();
	return 0;
}