#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
typedef pair<int,int> ii;
vector<int> sz, dep;
vector<vector<ii>> adj;
void dfs(int cur, int par) {
sz[cur] = 1;
for (auto nx : adj[cur]) {
if (nx.fi == par) continue;
dfs(nx.fi,cur);
sz[cur] += sz[nx.fi];
}
}
int maxDist(int cur, int par) {
int ret = dep[cur];
for (auto nx : adj[cur]) {
if (nx.fi == par) continue;
dep[nx.fi] = dep[cur]+nx.se;
ret = max(ret,maxDist(nx.fi,cur));
}
return ret;
}
int centroid(int cur, int par, int sub) {
for (auto nx : adj[cur]) {
if (nx.fi == par) continue;
if (sz[nx.fi]*2 >= sub) return centroid(nx.fi,cur,sub);
}
return cur;
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
adj = vector<vector<ii>>(N);
for (int i = 0; i < M; i++) {
adj[A[i]].push_back(ii(B[i],T[i]));
adj[B[i]].push_back(ii(A[i],T[i]));
}
sz = dep = vector<int>(N,0);
vector<int> tmp;
for (int i = 0; i < N; i++) {
if (!sz[i]) {
dfs(i,-1);
int cent = centroid(i,-1,sz[i]);
int maxi = maxDist(cent,-1);
tmp.push_back(maxi);
}
}
sort(tmp.rbegin(),tmp.rend());
if (tmp.size() == 1) return tmp[0];
else {
int ans = tmp[0]+tmp[1]+L;
if (tmp.size() >= 3) ans = max(ans,tmp[1]+tmp[2]+2*L);
return ans;
}
}
