【模板】Link-Cut Tree

#include<cstdio>
#include<algorithm>
#define N 500010
#define rg register
#define ls (c[u][0])
#define rs (c[u][1])
using namespace std;
int n,m,x,y,opt,top,val[N],c[N][2],fa[N],xr[N],st[N],rev[N];
inline int read(){
    int k=0,f=1; char c=getchar();
    while(c<'0'||c>'9')c=='-'&&(f=-1),c=getchar();
    while('0'<=c&&c<='9')k=k*10+c-'0',c=getchar();
    return k*f;
}
inline bool isroot(int u){
    return c[fa[u]][0]!=u&&c[fa[u]][1]!=u;
}
inline bool which(int u){
    return c[fa[u]][1]==u;
}
inline void pushup(int u){
    xr[u]=xr[ls]^xr[rs]^val[u];
}
inline void pushdown(int u){
    rev[ls]^=1; rev[rs]^=1; rev[u]=0; swap(ls,rs);
}
void rotate(int u){
    int f=fa[u],gf=fa[f],wh=which(u);
    if(!isroot(f)) c[gf][which(f)]=u;
    fa[u]=gf; fa[f]=u; fa[c[u][wh^1]]=f;
    c[f][wh]=c[u][wh^1]; c[u][wh^1]=f;
    pushup(f); pushup(u);
}
void splay(int u){
    st[top=1]=u;
    for(rg int i=u;!isroot(i);i=fa[i]) st[++top]=fa[i];
    for(rg int i=top;i;i--) if(rev[st[i]]) pushdown(st[i]);
    while(!isroot(u)){
        if(!isroot(fa[u])) rotate(which(u)==which(fa[u])?fa[u]:u);
        rotate(u);
    }
}
inline void access(int u){
    for(rg int son=0;u;son=u,u=fa[u]) splay(u),c[u][1]=son,pushup(u);
}
inline void makeroot(int u){
    access(u); splay(u); rev[u]^=1;
}
int find(int u){
    access(u); splay(u);
    while(ls) u=ls; return u;
}
void split(int x,int y){
    makeroot(x); access(y); splay(y);
}
void cut(int x,int y){
    split(x,y); bool goright=0;
    int t=c[y][0];
    while(c[t][1]) t=c[t][1],goright=1;
    if(t==x&&goright) c[fa[t]][1]=0,fa[x]=0;
    if(t==x&&(!goright)) c[y][0]=0,fa[x]=0;
}
void link(int x,int y){
    makeroot(x); fa[x]=y;
}
int main(){
    n=read(); m=read();
    for(rg int i=1;i<=n;i++) val[i]=xr[i]=read();
    while(m--){
        opt=read(); x=read(); y=read();
        if(opt==0) split(x,y),printf("%d
",xr[y]);
        if(opt==1) if(find(x)!=find(y))link(x,y);
        if(opt==2) if(find(x)==find(y)) cut(x,y);
        if(opt==3) access(x),splay(x),val[x]=y,pushup(x);
    }
    return 0;
}