bzoj2631: tree

话说bzoj上叫tree的题可真多...

题目大意：路径加，路径乘，路径求和，加边删边。

思路：动态树搞搞就行了，两个标记要注意。

#include<cstdio>
#include<cstring>
#include<algorithm>
#define ll unsigned int
#define ls c[x][0]
#define rs c[x][1]
const int mod=51061,maxn=100010; 
using namespace std;
int n,m;char op[2];

struct LCT{
	int fa[maxn],c[maxn][2],size[maxn],rev[maxn];
	ll sum[maxn],val[maxn],mul[maxn],add[maxn];
	bool isroot(int x){return c[fa[x]][0]!=x&&c[fa[x]][1]!=x;}
	int which(int x){return c[fa[x]][1]==x;}
	void update(int x){
//		printf("update%d %d %d
",x,sum[x],size[x]);
		sum[x]=(sum[ls]+sum[rs]+val[x])%mod;
		size[x]=(size[ls]+size[rs]+1)%mod;	
	}
	void cal(int x,int m,int a){
		if (!x) return ;
		val[x]=(val[x]*m+a)%mod;
		sum[x]=(sum[x]*m+a*size[x])%mod;
		add[x]=(add[x]*m+a)%mod;
		mul[x]=(mul[x]*m)%mod;
//		printf("%d %d %d %d
",x,sum[x],mul[x],add[x]);
	}
	void flip(int x){swap(c[x][0],c[x][1]),rev[x]^=1;}
	void down(int x){
		if (rev[x]) flip(c[x][0]),flip(c[x][1]),rev[x]^=1;
		if (mul[x]!=1||add[x]) cal(ls,mul[x],add[x]),cal(rs,mul[x],add[x]),mul[x]=1,add[x]=0;
	}
	void relax(int x){if (!isroot(x)) relax(fa[x]);down(x);}
	void rotate(int x){
		int y=fa[x],z=fa[y],nx=which(x),ny=which(y);
//		printf("%d %d %d %d
",x,sum[x],mul[x],add[x]);
		fa[c[x][!nx]]=y,c[y][nx]=c[x][!nx];
		fa[x]=z;if (!isroot(y)) c[z][ny]=x;
		fa[y]=x,c[x][!nx]=y;update(y);
	}
	void splay(int x){
		relax(x);
		while (!isroot(x)){
			if (isroot(fa[x])) rotate(x);
			else if (which(x)==which(fa[x])) rotate(fa[x]),rotate(x);
			else rotate(x),rotate(x);
		}
		update(x);
	}
	void access(int x){for (int p=0;x;x=fa[x]) splay(x),fa[c[x][1]=p]=x,update(x),p=x;}
	void makeroot(int x){access(x),splay(x),flip(x);}
	void link(int a,int b){makeroot(a),fa[a]=b;}
	void cut(int a,int b){makeroot(a),access(b),splay(b),c[b][0]=fa[a]=0;}	
	void change(int a1,int b1,int a2,int b2){cut(a1,b1),link(a2,b2);}
	void qsum(int a,int b){makeroot(a),access(b),splay(b),printf("%d
",sum[b]);}
	void modify(int a,int b,int m,int ad){makeroot(a),access(b),splay(b),cal(b,m,ad);}
}T;

int main(){
	scanf("%d%d",&n,&m);
	for (int i=1;i<=n;i++) T.size[i]=T.val[i]=T.sum[i]=T.mul[i]=1;
	for (int i=1,a,b;i<n;i++) scanf("%d%d",&a,&b),T.link(a,b);
	for (int i=1,a,b,c,d;i<=m;i++){
		scanf("%s",op);
		if (op[0]=='+') scanf("%d%d%d",&a,&b,&c),T.modify(a,b,1,c);
		else if (op[0]=='-') scanf("%d%d%d%d",&a,&b,&c,&d),T.change(a,b,c,d);
		else if (op[0]=='*') scanf("%d%d%d",&a,&b,&c),T.modify(a,b,c,0);
		else scanf("%d%d",&a,&b),T.qsum(a,b);
	}
	return 0;
}