欢迎访问~原文出处——博客园-zhouzhendong
去博客园看该题解
题目传送门 - BZOJ3091
题意概括
鉴于本人语文不好,此题的描述原题很清晰,废话不多,请看原题。
可怕,原题是图片,不可以复制题目+删掉废话了……
题解
http://blog.csdn.net/popoqqq/article/details/40823659
这位大佬写的很好。
我的代码在找错的时候一边找,一边该,然后发现和他改的好像……
代码
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
#include <cmath>
using namespace std;
typedef long long LL;
const int N=50005;
struct Gragh{
int cnt,y[N*2],nxt[N*2],fst[N];
void clear(){
cnt=0;
memset(fst,0,sizeof fst);
}
void add(int a,int b){
y[++cnt]=b,nxt[cnt]=fst[a],fst[a]=cnt;
}
}g;
int n,m;
int fa[N],son[N][2],rev[N];
LL size[N],val[N],add[N],sum[N],Lsum[N],Rsum[N],Exp[N];
bool isroot(int x){
return son[fa[x]][0]!=x&&son[fa[x]][1]!=x;
}
void pushup(int x){
int ls=son[x][0],rs=son[x][1],lsz=size[ls],rsz=size[rs];
size[x]=lsz+rsz+1;
sum[x]=sum[ls]+sum[rs]+val[x];
Lsum[x]=Lsum[ls]+(lsz+1)*val[x]+Lsum[rs]+sum[rs]*(lsz+1);
Rsum[x]=Rsum[rs]+(rsz+1)*val[x]+Rsum[ls]+sum[ls]*(rsz+1);
Exp[x]=Exp[ls]+Exp[rs]+Lsum[ls]*(rsz+1)+Rsum[rs]*(lsz+1)+val[x]*(lsz+1)*(rsz+1);
}
void pushson(int x,LL v){
if (!x)
return;
val[x]+=v,sum[x]+=v*size[x],add[x]+=v;
Lsum[x]+=v*size[x]*(size[x]+1)/2;
Rsum[x]+=v*size[x]*(size[x]+1)/2;
Exp[x]+=v*size[x]*(size[x]+1)*(size[x]+2)/6;
}
void pushrev(int x){
rev[x]^=1;
swap(son[x][0],son[x][1]);
swap(Lsum[x],Rsum[x]);
}
void pushdown(int x){
int &ls=son[x][0],&rs=son[x][1];
if (rev[x]){
rev[x]=0;
pushrev(ls);
pushrev(rs);
}
if (add[x]){
LL &a=add[x];
pushson(ls,a);
pushson(rs,a);
a=0;
}
}
void pushadd(int x){
if (!isroot(x))
pushadd(fa[x]);
pushdown(x);
}
int wson(int x){
return son[fa[x]][1]==x;
}
void rotate(int x){
if (isroot(x))
return;
int y=fa[x],z=fa[y],L=wson(x),R=L^1;
if (!isroot(y))
son[z][wson(y)]=x;
fa[x]=z,fa[y]=x,fa[son[x][R]]=y;
son[y][L]=son[x][R],son[x][R]=y;
pushup(y),pushup(x);
}
void splay(int x){
pushadd(x);
for (int y=fa[x];!isroot(x);rotate(x),y=fa[x])
if (!isroot(y))
rotate(wson(x)==wson(y)?y:x);
}
void access(int x){
int t=0;
while (x){
splay(x);
son[x][1]=t;
pushup(x);
t=x;
x=fa[x];
}
}
void rever(int x){
access(x);
splay(x);
pushrev(x);
}
void link(int x,int y){
rever(x);
fa[x]=y;
}
void cut(int x,int y){
rever(x);
access(y);
splay(y);
fa[x]=son[y][0]=0;
}
int find(int x){
access(x);
splay(x);
while (1){
pushdown(x);
if (son[x][0])
x=son[x][0];
else
break;
}
return x;
}
void dfs(int x,int pre){
fa[x]=pre;
for (int i=g.fst[x];i;i=g.nxt[i])
if (g.y[i]!=pre)
dfs(g.y[i],x);
}
LL gcd(LL a,LL b){
return b==0?a:gcd(b,a%b);
}
void solve(int x,int y){
if (find(x)!=find(y)){
puts("-1");
return;
}
rever(x);
access(y);
splay(y);
LL a=Exp[y];
LL b=size[y]*(size[y]+1)/2;
LL Gcd=gcd(a,b);
a/=Gcd,b/=Gcd;
printf("%lld/%lld\n",a,b);
}
int main(){
scanf("%d%d",&n,&m);
for (int i=1;i<=n;i++){
scanf("%lld",&val[i]);
fa[i]=son[i][0]=son[i][1]=rev[i]=0;
size[i]=1,Exp[i]=Lsum[i]=Rsum[i]=sum[i]=val[i],add[i]=0;
}
g.clear();
for (int i=1,a,b;i<n;i++){
scanf("%d%d",&a,&b);
g.add(a,b),g.add(b,a);
}
dfs(1,0);
for (int i=1;i<=m;i++){
int op,x,y;
LL v;
scanf("%d%d%d",&op,&x,&y);
if (op==1){
if (find(x)==find(y))
cut(x,y);
}
else if (op==2){
if (find(x)!=find(y))
link(x,y);
}
else if (op==3){
scanf("%lld",&v);
if (find(x)!=find(y))
continue;
rever(x);
access(y);
splay(y);
pushson(y,v);
}
else
solve(x,y);
}
return 0;
}