fartherst node by opi

#include<bits/stdc++.h>
#define pb push_back
#define siz 30005
#define inf 1000000004
#define mp make_pair
#define rep(i,n) for(int i=0;i<n;i++)
#define ll long long
#define pii pair<int,int>
using namespace std;
int fx[]={0,0,-1,+1};
int fy[]={-1,1,0,0};
int u,x,mi=0,ans=0,y,cnt=1;
vector<pii> vec[siz];
int vis[siz]={0};
int dis[siz];
int DKT(int u)
{
    memset(vis,0,sizeof vis);
    memset(dis,0,sizeof dis);
    queue<int>q;
    q.push(u);
    vis[u]=1;
    dis[u]=0;
    mi=0,ans=0;
    while(!q.empty())
    {
         int v=q.front();
         q.pop();
         rep(i,vec[v].size())
         {
             int w=vec[v][i].first;
             int we=vec[v][i].second;
             if(vis[w]==0)
             {
                 vis[w]=1;
                 dis[w]=dis[v]+we;
                 if(dis[w]>mi){mi=dis[w];ans=w;}
                 q.push(w);
             }

         }
    }
    return ans;

}
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        rep(i,siz)
        vec[i].clear();
        int n;cin>>n;n--;
        while(n--)
        {
            scanf("%d %d %d",&u,&x,&y);
            vec[u].pb(mp(x,y));
            vec[x].pb(mp(u,y));
        }
        int v=DKT(u);
        int w=DKT(v);
        printf("Case %d: %d\n",cnt++,dis[w]);
    }
return 0;
}
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