【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][],fa[N],xr[N],st[N],rev[N];
 inline int read(){
     int k=,f=; char c=getchar();
     while(c<''||c>'')c=='-'&&(f=-),c=getchar();
     while(''<=c&&c<='')k=k*+c-'',c=getchar();
     return k*f;
 }
 inline bool isroot(int u){
     return c[fa[u]][]!=u&&c[fa[u]][]!=u;
 }
 inline bool which(int u){
     return c[fa[u]][]==u;
 }
 inline void pushup(int u){
     xr[u]=xr[ls]^xr[rs]^val[u];
 }
 inline void pushdown(int u){
     rev[ls]^=; rev[rs]^=; rev[u]=; 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^]]=f;
     c[f][wh]=c[u][wh^]; c[u][wh^]=f;
     pushup(f); pushup(u);
 }
 void splay(int u){
     st[top=]=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=;u;son=u,u=fa[u]) splay(u),c[u][]=son,pushup(u);
 }
 inline void makeroot(int u){
     access(u); splay(u); rev[u]^=;
 }
 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=;
     int t=c[y][];
     while(c[t][]) t=c[t][],goright=;
     if(t==x&&goright) c[fa[t]][]=,fa[x]=;
     if(t==x&&(!goright)) c[y][]=,fa[x]=;
 }
 void link(int x,int y){
     makeroot(x); fa[x]=y;
 }
 int main(){
     n=read(); m=read();
     for(rg int i=;i<=n;i++) val[i]=xr[i]=read();
     while(m--){
         opt=read(); x=read(); y=read();
         if(opt==) split(x,y),printf("%d\n",xr[y]);
         if(opt==) if(find(x)!=find(y))link(x,y);
         if(opt==) if(find(x)==find(y)) cut(x,y);
         if(opt==) access(x),splay(x),val[x]=y,pushup(x);
     }
     return ;
 }