bzoj 2631 LCT

/**************************************************************
    Problem: 2631
    User: wangyucheng
    Language: C++
    Result: Accepted
    Time:18408 ms
    Memory:9252 kb
****************************************************************/
 
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
#define N 110000
#define uint unsigned int
int rt[N];
int ch[N][2];
int pre[N];
uint s[N],c[N];
uint sum[N];
uint siz[N];
int rev[N];
uint val[N];
const uint mod=51061;
int n,q;
int nn,e[N],ne[N*2],v[N*2];
void add(int x,int y){
    ne[++nn]=e[x],e[x]=nn,v[nn]=y;
}
void mul(int x,uint y){
    if(!x)return;
    sum[x]=(sum[x]*y)%mod;
    val[x]=(val[x]*y)%mod;
    s[x]=(s[x]*y)%mod;
    c[x]=(c[x]*y)%mod;
}
void revs(int x){
    if(!x)return;
    rev[x]^=1;
    swap(ch[x][0],ch[x][1]);
}
void plu(int x,uint y){
    if(!x)return;
    val[x]=(val[x]+y)%mod;
    sum[x]=(siz[x]%mod*y+sum[x])%mod;
    s[x]=(s[x]+y)%mod;
}
void push(int x){
    if(rev[x]){
        revs(ch[x][0]);
        revs(ch[x][1]);
        rev[x]=0;
    }
    if(c[x]!=1){
        mul(ch[x][0],c[x]);
        mul(ch[x][1],c[x]);
        c[x]=1;
    }
    if(s[x]){
         plu(ch[x][0],s[x]);
         plu(ch[x][1],s[x]);
        s[x]=0;
    }
}
void up(int x){
    sum[x]=(sum[ch[x][0]]+sum[ch[x][1]]+val[x])%mod;
    siz[x]=siz[ch[x][0]]+siz[ch[x][1]]+1;   
}
void rotate(int x){
    int y=pre[x],z=pre[y],k=ch[y][0]==x;
    pre[ch[y][!k]=ch[x][k]]=y;
    pre[ch[x][k]=y]=x;
    pre[x]=z;
    if(!rt[y])ch[z][ch[z][1]==y]=x;
    else rt[y]=0,rt[x]=1;
    up(y);
}
void dfs(int x){
    if(!rt[x])dfs(pre[x]);
    push(x);
}
void splay(int x){
    dfs(x);
    int y,z;
    for(;!rt[x];){
        y=pre[x],z=pre[y];
        if(rt[y])rotate(x);
        else if((ch[y][1]==x)^(ch[z][1]==y))rotate(x),rotate(x);
        else rotate(y),rotate(x);       
    }
    up(x);
}
int acess(int x){
    int y=0;
    for(;x;y=x,x=pre[x]){
        splay(x);
        rt[ch[x][1]]=1;
        ch[x][1]=y;
        rt[y]=0;
        up(x);
    }
    return y;
}
void cut(int x,int y){
    acess(y);
    splay(x);
    if(pre[x]==y)pre[x]=0;
    else{
        acess(x);
        splay(y);
        pre[y]=0;
    }
}
void makeroot(int x){
    acess(x);
    splay(x);
    revs(x);
}
void link(int x,int y){
    makeroot(x);
    pre[x]=y;
}
int qu[N],he,bo;
void init(){
    for(int i=1;i<=n;i++){
        c[i]=1,siz[i]=1;
        val[i]=1;
        sum[i]=1;
        rt[i]=1;
    }
    int x;
    qu[he=bo=1]=1;
    while(he>=bo){
        for(int i=e[x=qu[bo++]];i;i=ne[i]){
            if(!pre[v[i]]&&v[i]!=1)pre[v[i]]=x,qu[++he]=v[i];
        }
    }
}
int ask(int a,int b){
    acess(a);
    int y=acess(b);
    if(y==a)return (sum[ch[a][1]]+val[a])%mod;
    splay(a);
    return (sum[ch[y][1]]+val[y]+sum[a])%mod;
}
void jia(int a,int b,uint z){
     acess(a);
     z%=mod;
     int y=acess(b);
      if(y==a){
        plu(ch[y][1],z);
        val[y]=(val[y]+z)%mod;
        up(y);
          return;
      }
      splay(a);
      plu(a,z);
      plu(ch[y][1],z);
      val[y]=(val[y]+z)%mod;
      up(y);
}
void cheng(int a,int b,uint z){
    acess(a);
    int y=acess(b);
    z%=mod;
    if(y==a){
        mul(ch[y][1],z);
        val[y]=(val[y]*z)%mod;
        up(y);
        return;
    }
    splay(a);
    mul(a,z);
    mul(ch[y][1],z);
    val[y]=(val[y]*z)%mod;
    up(y);
}
int main(){
    scanf("%d%d",&n,&q);
    for(int i=1;i<n;i++){
        int a,b;
        scanf("%d%d",&a,&b);
        add(a,b);
        add(b,a);
    }
    init();
    for(int i=1;i<=q;i++){
        char in;
        int a,b,g,h;
        scanf(" %c",&in);
        if(in==‘+‘){
            scanf("%d%d%d",&a,&b,&g);
            jia(a,b,g);
        }
        if(in==‘/‘){
            scanf("%d%d",&a,&b);
            printf("%d\n",ask(a,b));
        }
        if(in==‘*‘){
            scanf("%d%d%d",&a,&b,&g);
            cheng(a,b,g);
        }
        if(in==‘-‘){
            scanf("%d%d%d%d",&a,&b,&g,&h);
            cut(a,b);
            link(g,h);
        }
    }
      
}