[LOJ 6159] 最长树链

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<map>
#include<queue>
#include<vector> 
#include<cmath>
using namespace std;
inline int read()
{
    int f=1,ans=0;char c;
    while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){ans=ans*10+c-‘0‘;c=getchar();}
    return f*ans;
}
map<int,int> ma;
struct node{
    int u,v,nex;
}x[200001];
int cnt,n,head[100001];
void add(int u,int v)
{
    x[cnt].u=u,x[cnt].v=v,x[cnt].nex=head[u],head[u]=cnt++;
}
int v[100001],sry,have[100001];
int vis[100001];
int dis[100001];
vector<int> ve[100005];
int vis1[100001];
int maxn;
int bfs(int u)
{
    queue<int> que;
    int ans=u;
    que.push(u);
    vis[u]=1,dis[u]=1;
    while(!que.empty())
    {
        int xx=que.front();que.pop();
        for(int i=head[xx];i!=-1;i=x[i].nex)
        {
            if(have[x[i].v]==0) continue;
            if(vis[x[i].v]) continue;
            vis[x[i].v]=1;
            dis[x[i].v]=dis[xx]+1;
            if(dis[x[i].v]>dis[ans]) ans=x[i].v;
            que.push(x[i].v);
        }
    }
    while(!que.empty()) que.pop();
    que.push(ans),vis1[ans]=1,dis[ans]=1;
    while(!que.empty())
    {
        int xx=que.front();que.pop();
        for(int i=head[xx];i!=-1;i=x[i].nex)
        {
            if(have[x[i].v]==0) continue;
            if(vis1[x[i].v]) continue;
            dis[x[i].v]=dis[xx]+1;
            vis1[x[i].v]=1;
            if(dis[x[i].v]>dis[ans]) ans=x[i].v;
            que.push(x[i].v);
        }
    }
    return dis[ans];
}
int main()
{
    memset(head,-1,sizeof(head));
    n=read();
    for(int i=1;i<n;i++)
    {
        int u=read(),v=read();
        add(u,v),add(v,u);
    }
    for(int i=1;i<=n;i++) v[i]=read();
    for(int i=1;i<=n;i++) 
    {
        int x=v[i];
        for(int j=2;j<=sqrt(x);j++) 
        {
            if(x%j!=0) continue;
            if(ma[j]==0) ma[j]=++sry;
            ve[ma[j]].push_back(i);
            while(x%j==0) x/=j;
        }
        if(x!=1) 
        {
            if(ma[x]==0) ma[x]=++sry;
            ve[ma[x]].push_back(i);
        }
    }
    for(int i=1;i<=sry;i++)
    {
        int size=ve[i].size();
        for(int j=0;j<size;j++) have[ve[i][j]]=1,vis[ve[i][j]]=0,vis1[ve[i][j]]=0;
        for(int j=0;j<size;j++) 
        {
            if(vis[ve[i][j]]==1) continue;
            maxn=max(maxn,bfs(ve[i][j]));
        }
        for(int j=0;j<size;j++) have[ve[i][j]]=0,vis[ve[i][j]]=1,vis1[ve[i][j]]=1;
    }
    cout<<maxn;
}