#include <bits/stdc++.h>
#include "dreaming.h"
#define ff first
#define ss second
using namespace std;
int inf = INT_MAX;
vector<vector<pair<int,int> > > gp;
vector<int> vis, dis,parents;
void dfs(int u, int pes){
vis[u] = 1;
dis[u] += pes;
for(auto it: gp[u]){
if(vis[it.ff] == 0){
vis[it.ff] = 1;
parents[it.ff] = u;
dfs(it.ff, it.ss + dis[u]);
}
}
}
int radius(int u){
int distan1 = dis[u], distan2 = 0, ans = dis[u];
while(parents[u] != -1){
ans = min(ans,max(distan1,distan2));
int pospar = -1;
for(int i = 0; i < (int)gp[u].size(); i++){
if(gp[u][i].ff == parents[u]) pospar = gp[u][i].ss;
}
u = parents[u];
distan1 -= pospar; distan2 += pospar;
}
return ans;
}
int fndext(int n){
int ans = 0, maypes = 0;
for(int i = 0; i < n; i++){
if(dis[i] > maypes){
maypes = dis[i];
ans = i;
}
}
return ans;
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
gp.resize(N); vis.resize(N); dis.resize(N); parents.resize(N);
for(int i = 0; i < N; i++) vis[i] = 0, dis[i] = 0;
for(int i = 0; i < M; i++){
gp[A[i]].push_back(make_pair(B[i],T[i]));
gp[B[i]].push_back(make_pair(A[i],T[i]));
}
dfs(0,0);
int nodext1, nodext2, nodext11, nodext22;
nodext1 = fndext(N);
dis.clear();
for(int i = 0; i < N; i++) vis[i] = 0, dis[i] = 0;
parents[nodext1] = -1;
dfs(nodext1,0);
nodext2 = fndext(N);
int diam1 = dis[nodext2], diam2 = 0, radi1 = radius(nodext2), radi2 = 0;
for(int i = 0; i < N; i++) dis[i] = 0;
int posext;
for(int i = 0; i < N; i++){
if(vis[i] == 0){
dfs(i,0);
posext = i;
}
}
bool calc = false;
for(int i = 0; i < N; i++){
if(dis[i] != 0) calc = true;
}
if(calc) nodext11 = fndext(N);
else nodext11 = posext;
dis.clear();
for(int i = 0; i < N; i++) vis[i] = 0, dis[i] = 0;
parents[nodext11] = -1;
dfs(nodext11,0);
nodext22 = fndext(N);
diam2 = dis[nodext22];
radi2 = radius(nodext22);
return max(diam1,max(diam2,radi1 + radi2 + L));
}
