LCT模板

#include<bits/stdc++.h>
using namespace std;
int fa[500010],ch[500010][2],sum[500010],v[500010],rev[500010],lb[500010],bf[500010][3],n,q,type,ty,last;
bool root(int x){ return ((fa[x]==0)or((ch[fa[x]][0]!=x)and(ch[fa[x]][1]!=x))); }
bool lch(int x){ return (ch[fa[x]][0]==x); }
void up(int x){ sum[x]=sum[ch[x][0]]+v[x]+sum[ch[x][1]]; }
void down(int x)
{
    if(rev[x]==0)return;
    rev[x]=0; swap(ch[x][0],ch[x][1]); if(ch[x][0])rev[ch[x][0]]^=1; if(ch[x][1])rev[ch[x][1]]^=1;
}
void rot(int x)
{
    if((x==0)or(root(x)))return;
    int y=fa[x]; int t=fa[y];
    if(ch[t][0]==y)ch[t][0]=x;else if(ch[t][1]==y)ch[t][1]=x; fa[x]=t; fa[y]=x; 
    if(ch[y][0]==x){ ch[y][0]=ch[x][1]; if(ch[x][1])fa[ch[x][1]]=y; ch[x][1]=y; }
    else{ ch[y][1]=ch[x][0]; if(ch[x][0])fa[ch[x][0]]=y; ch[x][0]=y; }
    up(y); up(x); if(t)up(t);
}
void splay(int x)
{
    if(x==0)return; int xx=x; int cnt=0;
    while(!root(xx)){ lb[++cnt]=xx; xx=fa[xx]; } lb[++cnt]=xx;
    for(int i=cnt;i>=1;i--)down(lb[i]);
    while(!root(x)){ if(!root(fa[x])){ if((lch(x))^(lch(fa[x])))rot(x);else rot(fa[x]); } rot(x); }
}
int access(int x)
{
    int t=0;
    while(x!=0){ splay(x); ch[x][1]=t; up(x); if(t)fa[t]=x; t=x; x=fa[x]; } 
    return t;
}
void cut(int x,int y)
{
    access(x); int z=access(y); splay(x);
    if(x==z){ ch[x][1]=0; fa[y]=0; up(x); }else fa[x]=0;
}
void link(int x,int y)
{
    access(x); splay(x); rev[x]^=1; fa[x]=y;
}
int qsum(int x,int y)
{
    access(x); int z=access(y); splay(x);
    if(x==z)return v[x]+sum[ch[x][1]];else return sum[x]+v[z]+sum[ch[z][1]]; 
}