指针版P3690 【模板】Link Cut Tree （动态树）

题面

传送门

题解

鉴于数组版实在是太慢我用指针版重新写了一遍

代码基本是借鉴了lxl某道关于\(LCT\)的题

//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)
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;
}
inline int getop(){R char ch;while((ch=getc())>'9'||ch<'0');return ch-'0';}
char sr[1<<21],z[20];int C=-1,Z=0;
inline void Ot(){fwrite(sr,1,C+1,stdout),C=-1;}
void print(R int x){
    if(C>1<<20)Ot();if(x<0)sr[++C]='-',x=-x;
    while(z[++Z]=x%10+48,x/=10);
    while(sr[++C]=z[Z],--Z);sr[++C]='\n';
}
const int N=3e5+5;
struct node;typedef node* ptr;
inline void swap(R ptr &x,R ptr &y){R ptr t=x;x=y,y=t;}
struct node{
	ptr lc,rc,fa;int s,v,r;
	inline node();
	inline void ppd(){swap(lc,rc),r^=1;}
	inline void pd(){if(r)lc->ppd(),rc->ppd(),r=0;}
	inline ptr upd(){return s=lc->s^rc->s^v,this;}
}e[N];
inline node::node(){fa=lc=rc=e;}
inline bool isrt(R ptr p){return p->fa->lc!=p&&p->fa->rc!=p;}
void rotate(ptr p){
    ptr s=p->fa,t=s->fa;
    if(!isrt(s))(t->lc==s?t->lc:t->rc)=p;
    p->fa=t,s->fa=p;
    if(s->lc==p)s->lc=p->rc,p->rc->fa=s,p->rc=s->upd();
        else s->rc=p->lc,p->lc->fa=s,p->lc=s->upd();
}
void push(ptr p){if(!isrt(p))push(p->fa);p->pd();}
ptr splay(ptr p){
	push(p);
	while(!isrt(p)){
		if(!isrt(p->fa))rotate(p->fa->lc==p^p->fa->fa->lc==p->fa?p:p->fa);
		rotate(p);
	}
	return p->upd();
}
ptr exp(ptr p){
	ptr s=e;
	while(p!=e)splay(p)->rc=s,s=p->upd(),p=p->fa;
	return s;
}
inline void makert(ptr p){exp(p),splay(p)->ppd();}
inline ptr split(ptr s,ptr t){return makert(s),exp(t);}
ptr findrt(ptr p){
	exp(p),splay(p)->pd();
	while(p->lc!=e)(p=p->lc)->pd();
	return p;
}
void link(ptr s,ptr t){
	makert(s);
	if(findrt(t)!=s)s->fa=t;
	//虚儿子接上之后根本不用upd
}
void cut(ptr s,ptr t){
	makert(s);
	if(findrt(t)==s&&s->fa==t&&s->rc==e)
		s->fa=t->lc=e,t->upd();
}
int n,m,op,u,v;
int main(){
//	freopen("testdata.in","r",stdin);
//	freopen("testdata.out","w",stdout);
	n=read(),m=read();
	fp(i,1,n)(e+i)->v=read(),(e+i)->upd();
	while(m--){
		op=getop(),u=read(),v=read();
		switch(op){
			case 0:print(split(e+u,e+v)->s);break;
			case 1:link(e+u,e+v);break;
			case 2:cut(e+u,e+v);break;
			case 3:splay(e+u),(e+u)->v=v,(e+u)->upd();break;
		}
	}
	return Ot(),0;
}