LOJ#120. 持久化序列（FHQ Treap）

题面

传送门

题解

可持久化(Treap)搞一搞

//minamoto
#include<bits/stdc++.h>
#define R register
#define inline __inline__ __attribute__((always_inline))
#define fp(i,a,b) for(R int i=(a),I=(b)+1;i<I;++i)
#define fd(i,a,b) for(R int i=(a),I=(b)-1;i>I;--i)
#define go(u) for(int i=head[u],v=e[i].v;i;i=e[i].nx,v=e[i].v)
template<class T>inline bool cmax(T&a,const T&b){return a<b?a=b,1:0;}
template<class T>inline bool cmin(T&a,const T&b){return a>b?a=b,1:0;}
using namespace std;
char buf[1<<21],*p1=buf,*p2=buf;
inline char getc(){return p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++;}
int read(){
    R int res,f=1;R char ch;
    while((ch=getc())>'9'||ch<'0')(ch=='-')&&(f=-1);
    for(res=ch-'0';(ch=getc())>='0'&&ch<='9';res=res*10+ch-'0');
    return res*f;
}
char sr[1<<21],z[20];int K=-1,Z=0;
inline void Ot(){fwrite(sr,1,K+1,stdout),K=-1;}
void print(R int x){
    if(K>1<<20)Ot();if(x<0)sr[++K]='-',x=-x;
    while(z[++Z]=x%10+48,x/=10);
    while(sr[++K]=z[Z],--Z);sr[++K]='
';
}
unsigned int aaa=19260817;
inline unsigned int rd(){aaa^=aaa>>15,aaa+=aaa<<12,aaa^=aaa>>3;return aaa;}
const int N=3e5+5,M=1e7+5;
struct node;typedef node* ptr;
struct node{
	ptr lc,rc;int sz,v;unsigned int pr;
	inline ptr init(R int val){return sz=1,v=val,pr=rd(),this;}
	inline ptr upd(){return sz=lc->sz+rc->sz+1,this;}
}e[M],*rt[N],*pp=e;
inline ptr newnode(R int v){return ++pp,pp->lc=pp->rc=e,pp->init(v);}
inline ptr cl(R ptr p){return ++pp,*pp=*p,pp;}
void split(ptr p,int k,ptr &s,ptr &t){
	if(p==e)return s=t=e,void();
	if(p->lc->sz<k)return s=cl(p),split(s->rc,k-s->lc->sz-1,s->rc,t),s->upd(),void();
	t=cl(p),split(t->lc,k,s,t->lc),t->upd();
}
ptr merge(ptr s,ptr t){
	if(s==e)return t;if(t==e)return s;
	if(s->pr<t->pr)return s->rc=merge(s->rc,t),s->upd();
	return t->lc=merge(s,t->lc),t->upd();
}
void push(ptr &rt,int k,int v){
	ptr s,t;
	split(rt,k-1,s,t),rt=merge(merge(s,newnode(v)),t);
}
void pop(ptr &rt,int k){
	ptr s,t,p,q;
	split(rt,k,s,t),split(s,k-1,p,q),rt=merge(p,t);
}
int query(ptr &rt,int k){
	ptr s,t,p,q;int now;
	split(rt,k,s,t),split(s,k-1,p,q),now=q->v;
	return rt=merge(merge(p,q),t),now;
}
int main(){
//	freopen("testdata.in","r",stdin);
//	freopen("testdata.out","w",stdout);
	rt[0]=e,e->lc=e->rc=e;
	for(int q=read(),i=0,op,id,k,x;q;--q){
		op=read(),id=read(),k=read(),rt[++i]=rt[id];
		switch(op){
			case 1:x=read(),push(rt[i],k,x);break;
			case 2:pop(rt[i],k);break;
			case 3:print(query(rt[i],k)),--i;break;
		}
	}
	return Ot(),0;
}