#include"dreaming.h"
#include<iostream>
#include<vector>
#include<algorithm>
#include<map>
using namespace std;
typedef long long ll;
vector<pair<ll,ll>>nodes[100000];
bool vis[100000];
vector<ll>node_list;
void dfs(ll node){
if(vis[node])
return;
vis[node]=true;
node_list.push_back(node);
for(auto ne:nodes[node])
dfs(ne.first);
}
map<pair<ll,ll>,pair<ll,ll>>dp;
pair<ll,ll>get_max_dist(ll node,ll prev){
if(dp.count({node,prev}))
return dp[{node,prev}];
pair<ll,ll>res={0,0};
for(auto ne:nodes[node]){
if(ne.first==prev)
continue;
{
ll curr=get_max_dist(ne.first,node).first+ne.second;
if(curr>=res.first){
res.second=res.first;
res.first=curr;
}else if(curr>res.second){
res.second=curr;
}
}
}
dp[{node,prev}]=res;
return res;
}
pair<ll,ll> get_diameter(ll root){
node_list.clear();
dfs(root);
/*cout<<"- ";
for(int i:node_list)
cout<<i<<" ";
cout<<"\n";*/
ll res=1e18,diam=0;
for(ll node:node_list){
//cout<<node<<": "<<get_max_dist(node,node)<<"\n";
auto r=get_max_dist(node,node);
res=min(res,r.first);
diam=max(diam,r.first+r.second);
}
return {res,diam};
}
int travelTime(int N,int M,int L,int A[],int B[],int T[]){
for(ll i=0;i<M;i++){
nodes[A[i]].emplace_back(B[i],T[i]);
nodes[B[i]].emplace_back(A[i],T[i]);
}
vector<ll>dists;
ll diam=0;
for(ll i=0;i<N;i++)
if(!vis[i]){
auto r=get_diameter(i);
dists.push_back(r.first);
diam=max(diam,r.second);
}
sort(dists.begin(),dists.end());
reverse(dists.begin(),dists.end());
if(dists.size()==1)
return max(dists[0],diam);
else if(dists.size()==2)
return max(dists[0]+dists[1]+L,diam);
else
return max(max(dists[0]+dists[1]+L,dists[1]+dists[2]+2*L),diam);
}
