洛谷3690：【模板】Link Cut Tree——题解

#include<algorithm>
#include<iostream>
#include<cstring>
#include<cctype>
#include<cstdio>
#include<vector>
#include<queue>
#include<cmath>
using namespace std;
const int N=3e5+5;
int n,m,r,fa[N],tr[N][2],rev[N],q[N],key[N],val[N];
inline int read(){
    int X=0,w=0;char ch=0;
    while(!isdigit(ch)){w|=ch==‘-‘;ch=getchar();}
    while(isdigit(ch))X=(X<<3)+(X<<1)+(ch^48),ch=getchar();
    return w?-X:X;
}
inline bool get(int x){
    return tr[fa[x]][1]==x;
}
inline bool isroot(int x){
    if(!fa[x])return 1;
    return tr[fa[x]][0]!=x&&tr[fa[x]][1]!=x;
}
inline void upt(int x){
    int ans=0;
    if(tr[x][0])ans^=val[tr[x][0]];
    if(tr[x][1])ans^=val[tr[x][1]];
    val[x]=key[x]^ans;
}
inline void pushrev(int x){
    if(!rev[x])return;
    swap(tr[x][0],tr[x][1]);
    if(tr[x][0])rev[tr[x][0]]^=1;
    if(tr[x][1])rev[tr[x][1]]^=1;
    rev[x]=0;
}
inline void rotate(int x){
    int y=fa[x],z=fa[y],b=tr[y][0]==x?tr[x][1]:tr[x][0];
    if(z&&!isroot(y))(tr[z][0]==y?tr[z][0]:tr[z][1])=x;
    fa[x]=z;fa[y]=x;b?fa[b]=y:0;
    if(tr[y][0]==x)tr[x][1]=y,tr[y][0]=b;
    else tr[x][0]=y,tr[y][1]=b;
    upt(y);upt(x);
}
inline void splay(int x){
    q[r=0]=x;
    for(int y=x;!isroot(y);y=fa[y])q[++r]=fa[y];
    for(int i=r;i>=0;i--)pushrev(q[i]);
    while(!isroot(x)){
    if(!isroot(fa[x]))
        rotate((get(x)==get(fa[x])?fa[x]:x));
    rotate(x);
    }
    upt(x);
}
inline void access(int x){
    for(int y=0;x;y=x,x=fa[x]){
    splay(x);tr[x][1]=y;
    if(y)fa[y]=x;
    }
}
inline int findroot(int x){
    access(x);splay(x);
    while(pushrev(x),tr[x][0])x=tr[x][0];
    splay(x);
    return x;
}
inline void makeroot(int x){
    access(x);splay(x);
    rev[x]^=1;
}
inline void link(int x,int y){
    makeroot(x);fa[x]=y;
}
inline void cut(int x,int y){
    makeroot(x);access(y);splay(y);
    tr[y][0]=0;fa[x]=0;
}
inline void split(int u,int v){
    makeroot(u);access(v);splay(v);
}
int main(){
    n=read(),m=read();
    for(int i=1;i<=n;i++)key[i]=read();
    for(int i=1;i<=m;i++){
    int op=read(),u=read(),v=read();
    if(op==0){
        split(u,v);
        printf("%d\n",val[v]);
    }
    if(op==1){
        if(findroot(u)!=findroot(v))link(u,v);
    }
    if(op==2){
        if(findroot(u)==findroot(v))cut(u,v);
    }
    if(op==3){
        access(u);splay(u);
        key[u]=v;upt(u);
    }
    }
    return 0;
}