bzoj 2631 tree

LCT简单题，但是标记有点恶心

就当复习SPLAY了吧。

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<cmath>
#define N 100050
#define int long long
#define mod 51061
using namespace std;
int n,m;
char ch[2];
struct Node{
    Node *ch[2],*fa;
    int id,now,sum,plus,times,size,rev;
    Node();
    void pushdown();
    void pushup();
}*null=new Node,tree[N];
Node :: Node(){
    fa=ch[0]=ch[1]=null;
    sum=now=times=1;id=plus=0;
}
void Plus(Node *x,int val){
    (x->plus+=val)%=mod;
    (x->sum+=val*x->size)%=mod;
    (x->now+=val)%=mod;
}
inline void Times(Node *x,int val){
    (x->times*=val)%=mod;
    (x->sum*=val)%=mod;
    (x->now*=val)%=mod;
    (x->plus*=val)%=mod;
}
void Node :: pushdown(){
    if(rev){
        swap(ch[0],ch[1]);
        if(ch[0]!=null)ch[0]->rev^=1;
        if(ch[1]!=null)ch[1]->rev^=1;
        rev=0;
    }
    if(times!=1){
        Times(ch[0],times);
        Times(ch[1],times);
        times=1;
    }
    if(plus){
        Plus(ch[0], plus);
        Plus(ch[1], plus);
        plus=0;
    }
    
}
void Node :: pushup(){
    sum=(ch[0]->sum+ch[1]->sum+now)%mod;
    size=ch[0]->size+ch[1]->size+1;
}
bool isroot(Node *x){
    return (x->fa->ch[0]!=x)&&(x->fa->ch[1]!=x);
}
void rotate(Node *x){
    Node *y=x->fa,*z=y->fa;
    int w=(y->ch[0]==x);
    x->ch[w]->fa=y;y->ch[w^1]=x->ch[w];
    y->fa=x;x->ch[w]=y;
    if(z->ch[0]==y)z->ch[0]=x;
    if(z->ch[1]==y)z->ch[1]=x;
    x->fa=z;
    y->pushup();x->pushup();
}
void splay(Node *x){
    Node *y,*z;
    x->pushdown();
    while(!isroot(x)){
        y=x->fa;z=y->fa;
        z->pushdown();y->pushdown();x->pushdown();
        if(((z->ch[0]==y)&&(y->ch[0]==x))||((z->ch[1]==y)&&(y->ch[1]==x)))rotate(y);
        rotate(x);
    }
}
void access(Node *x){
    Node *y=null;
    x->pushdown();
    while(x!=null){
        splay(x);
        x->ch[1]=y;
        x->pushup();
        y=x;x=x->fa;
    }
}
void make_root(Node *x){
    access(x);
    splay(x);
    x->rev^=1;
}
void link(Node *x,Node *y){
    make_root(x);
    x->fa=y;
}
void cut(Node *x,Node *y){
    make_root(x);
    access(y);
    splay(y);
    x->fa=y->ch[0]=null;
    y->pushup();
}
void query(Node *x,Node *y){
    make_root(x);
    access(y);
    splay(x);
    x->pushdown();
    printf("%lld
",x->sum %mod);
}
void make_plus(Node *x,Node *y,int z){
    make_root(x);
    access(y);
    splay(y);
    Plus(y,z);
}
void make_times(Node *x,Node *y,int z){
    make_root(x);
    access(y);
    splay(y);
    Times(y,z);
}
signed main(){
    null->ch[0]=null->ch[1]=null->fa=null;
    null->sum=null->plus=null->times=null->rev=null->size=0;
    scanf("%lld%lld",&n,&m);
    for(int i=1;i<=n;i++)tree[i].id=i;
    for(int i=1,u,v;i<n;i++){
        scanf("%lld%lld",&u,&v);
        link(&tree[u],&tree[v]);
    }
    for(int i=1,u,v,x,y;i<=m;i++){
        scanf("%s",ch);
        if(ch[0]=='+'){
            scanf("%lld%lld%lld",&u,&v,&x);
            make_plus(&tree[u],&tree[v],x);
        }
        if(ch[0]=='-'){
            scanf("%lld%lld%lld%lld",&u,&v,&x,&y);
            cut(&tree[u],&tree[v]);
            link(&tree[x],&tree[y]);
        }
        if(ch[0]=='*'){
            scanf("%lld%lld%lld",&u,&v,&x);
            make_times(&tree[u],&tree[v],x);
        }
        if(ch[0]=='/'){
            scanf("%lld%lld",&u,&v);
            query(&tree[u],&tree[v]);
        }
    }
    return 0;
}