#include "bits/stdc++.h"
#include <algorithm>
#include "dreaming.h"
using namespace std;
vector<vector<array<int, 2>>> g;
vector<bool> used;
vector<int> dis, nodes, path, par;
int n;
void dfs(int u, bool collect = 0, int p = -1) {
if (collect) {
nodes.push_back(u);
}
used[u] = 1;
par[u] = p;
for (auto &[v, w] : g[u]) {
if (v == p) continue;
dis[v] = dis[u] + w;
dfs(v, collect, u);
}
}
pair<int, vector<int>> findDiameter(int u) {
dis[u] = 0;
nodes.clear();
dfs(u, 1);
int start = 0;
for (auto i : nodes) if (dis[i] > dis[start]) start = i;
nodes.clear();
dis[start] = 0;
dfs(start, 1);
int finish = 0;
for (auto i : nodes) if (dis[i] > dis[finish]) finish = i;
nodes.clear();
vector<int> path;
for (int v = finish; v != -1; v = par[v])
path.push_back(v);
return {dis[finish], path};
}
array<int, 2> findCenter(int u) {
int ans = 1e9, cent;
auto [diameter, path] = findDiameter(u);
for (auto &i : path) {
int cur = max(dis[i], diameter - dis[i]);
if (cur <= ans) {
ans = cur;
cent = i;
}
}
return {ans, cent};
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
int m = M, l = L;
n = N;
dis.resize(n + 1, 0);
par.resize(n + 1, 0);
g.resize(n + 1);
used.assign(n + 1, false);
for (int i = 0; i < m; i++) {
int u = A[i], v = B[i], w = T[i];
u++, v++;
g[u].push_back({v, w});
g[v].push_back({u, w});
}
vector<array<int, 2>> mx;
for (int u = 1; u <= n; u++) {
if (used[u]) continue;
mx.push_back(findCenter(u));
}
sort(mx.rbegin(), mx.rend());
for (int i = 1; i < size(mx); i++) {
g[mx[i][1]].push_back({mx[0][1], l});
g[mx[0][1]].push_back({mx[i][1], l});
}
int ans = 0;
ans = findDiameter(1).first;
return ans;
}
