bzoj2631

  题目不难理解，模型也就是比较经典的LCT；

　但需要注意乘法标记和加法标记的下传。

（我难道会告诉你我因此wa了4，5遍吗?）；

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<string>
#include<cmath>
#include<algorithm>
using namespace std;
#define LL unsigned int
#define FILE "dealing"
#define up(i,j,n) for(LL i=(j);i<=(n);i++)
LL read(){
	int ch=getchar(),f=1,x=0;
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch<='9'&&ch>='0')x=(x<<1)+(x<<3)+ch-'0',ch=getchar();
	return f*x;
}
const LL maxn=100100,inf=1000000000,mod=51061;
LL n,m;
LL fa[maxn],c[maxn][2],v[maxn],delet[maxn],w[maxn],ch[maxn],q[maxn],top,rev[maxn],siz[maxn];
struct node{LL y,next;}e[maxn<<1];
LL len=0,linkk[maxn];
void insert(LL x,LL y){e[++len].y=y;e[len].next=linkk[x];linkk[x]=len;}
bool isroot(LL o){return c[fa[o]][1]!=o&&c[fa[o]][0]!=o;}
void updata(LL x){v[x]=(v[c[x][1]]+v[c[x][0]]+w[x])%mod;siz[x]=(siz[c[x][0]]+siz[c[x][1]]+1)%mod;}
void reve(LL x){swap(c[x][0],c[x][1]);rev[x]^=1;}
void dele(LL x,LL t){delet[x]=(delet[x]+t)%mod,v[x]=(v[x]+t*siz[x])%mod,w[x]=(w[x]+t)%mod;}
void cheng(LL x,LL c){v[x]=(v[x]*c)%mod,w[x]=(w[x]*c)%mod,ch[x]=(ch[x]*c)%mod,delet[x]=(delet[x]*c)%mod;}
void downdata(LL x){
	if(ch[x]!=1)cheng(c[x][0],ch[x]),cheng(c[x][1],ch[x]),ch[x]=1;
	if(delet[x])dele(c[x][0],delet[x]),dele(c[x][1],delet[x]),delet[x]=0;
	if(rev[x])rev[x]^=1,reve(c[x][0]),reve(c[x][1]);
}
void rotate(LL x){
	LL y=fa[x],z=fa[y];
	LL d=c[y][1]==x;
	if(!isroot(y))c[z][c[z][1]==y]=x;
	fa[x]=z,fa[y]=x;fa[c[x][d^1]]=y;
	c[y][d]=c[x][d^1],c[x][d^1]=y;
	updata(y);updata(x);
}
void splay(LL x){
	q[++top]=x;
	for(LL i=x;!isroot(i);i=fa[i])q[++top]=fa[i];
	while(top)downdata(q[top--]);
	while(!isroot(x)){
		LL y=fa[x],z=fa[y];
		if(!isroot(y)){
			if(c[y][1]==x^c[z][1]==y)rotate(x);
			else rotate(y);
		}
		rotate(x);
	}
}
void access(LL x){
	for(LL t=0;x;t=x,x=fa[x])splay(x),c[x][1]=t,updata(x);
}
void makeroot(LL x){
	access(x),splay(x),reve(x);
}
void link(LL x,LL y){
	makeroot(x),fa[x]=y;
}
void cut(LL x,LL y){
	makeroot(x);access(y);splay(y);fa[x]=0;c[y][0]=0;
}
void build(LL x){
	ch[x]=siz[x]=v[x]=w[x]=1;
	for(LL i=linkk[x];i;i=e[i].next){
		if(fa[x]==e[i].y)continue;
		fa[e[i].y]=x;
		build(e[i].y);
	}
}
int main(){
	freopen(FILE".in","r",stdin);
	freopen(FILE".out","w",stdout);
	n=read(),m=read();
	up(i,1,n-1){
		LL x=read(),y=read();
		insert(x,y);insert(y,x);
	}
	build(1);
	char s[10];LL x,y,c,u1,u2,v1,v2;
	while(m--){
		scanf("%s",s);
		if(s[0]=='+'){
			x=read(),y=read(),c=read();
			makeroot(x),access(y),splay(y);
			dele(y,c);
		}
		if(s[0]=='-'){
			u1=read(),v1=read(),u2=read(),v2=read();
			cut(u1,v1);
			link(u2,v2);
		}
		if(s[0]=='*'){
			x=read(),y=read(),c=read();
			makeroot(x);access(y);splay(y);
			cheng(y,c);
		}
		if(s[0]=='/'){
			x=read(),y=read();
			makeroot(x);access(y);splay(y);
			printf("%d
",v[y]);
		}
	}
	printf("%d
",clock());
	return 0;
}