Lvat_s Blog

LCT

#include<cstdio>
#include<algorithm>
using namespace std;

int n,m;

struct Node{
int rev;
Node *ch[2],*fa;
Node(Node *fat);
void Pushdown();
}*root[10005],*Null;

Node::Node(Node *fat){
fa=fat;
ch[0]=ch[1]=Null;
rev=0;
}

void Node::Pushdown(){
if(rev){
	if(ch[0]!=Null)ch[0]->rev^=1;
	if(ch[1]!=Null)ch[1]->rev^=1;
	swap(ch[0],ch[1]);
	rev=0;
}
}

int Notroot(Node *x){
return (x->fa->ch[0]==x)||(x->fa->ch[1]==x);
}

void Prepare(Node *x){
if(Notroot(x))Prepare(x->fa);
x->Pushdown();
}

void Rotate(Node *x,int kind){
Node *y=x->fa,*z=y->fa;
y->ch[!kind]=x->ch[kind];
if(x->ch[kind]!=Null)x->ch[kind]->fa=y;
x->fa=z;
if(Notroot(y))z->ch[z->ch[1]==y]=x;
y->fa=x;
x->ch[kind]=y;
}

void Splay(Node *x){
Prepare(x);
while(Notroot(x)){
	Node *y=x->fa,*z=y->fa;
	if(!Notroot(y))Rotate(x,y->ch[0]==x);
	else {
		if(y->ch[0]==x && z->ch[1]==y){Rotate(x,1);Rotate(x,0);}
		else if(y->ch[1]==x && z->ch[1]==y){Rotate(y,0);Rotate(x,0);}
		else if(y->ch[0]==x && z->ch[0]==y){Rotate(y,1);Rotate(x,1);}
		else {Rotate(x,0);Rotate(x,1);}
	}
}
}

void Access(Node *x){
for(Node *y=Null;x!=Null;y=x,x=x->fa){Splay(x);x->ch[1]=y;}
}

void Makeroot(Node *x){
Access(x);
Splay(x);
x->rev^=1;
}

void Link(Node *u,Node *v){
Makeroot(u);
u->fa=v;
}

void Cut(Node *u,Node *v){
Makeroot(u);
Access(v);
Splay(v);
if(v->ch[0]==u){v->ch[0]=Null;u->fa=Null;}
}

Node *Find(Node *x){
Access(x);
Splay(x);
while(x->ch[0]!=Null)x=x->ch[0];
return x;
}

Node *GetNull(){
Node *p=new Node(Null);
p->ch[0]=p->ch[1]=p->fa=p;
p->rev=0;
return p;
}

Node *ToLct(int x){
return root[x];
}

int main(){
freopen("2049.in","r",stdin);
freopen("2049.out","w",stdout);
scanf("%d %d",&n,&m);
Null=GetNull();
for(int i=1;i<=n;i++)root[i]=new Node(Null);
for(int i=1;i<=m;i++){
	int u,v;
	char s[10];
    scanf("%s %d %d",s,&u,&v);
    if(s[0]=='C')Link(ToLct(u),ToLct(v));
    if(s[0]=='D')Cut(ToLct(u),ToLct(v));
    if(s[0]=='Q'){
		if(Find(ToLct(u))==Find(ToLct(v)))puts("Yes");
		else puts("No");
	}
}
return 0;
}