#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define ll long long int
#define pii pair <int, int>
#define pb push_back
#define ff first
#define ss second
const int N = 1e5+5;
int dpt[N], cur[N], vis[N], mx;
pii dp[N][2];
vector<pii> E[N];
void calc(int nd, int pr, int w){
vis[nd] = 1;
vector<pii> vec;
for (auto i : E[nd]){
if (i.ff == pr) continue;
calc(i.ff, nd, w+i.ss);
vec.pb({dp[i.ff][0].ff+i.ss, i.ff});
}
sort(all(vec));
if (!vec.size()) return;
if (vec.size() == 1) dp[nd][0] = vec.back();
else{
dp[nd][0] = vec[vec.size()-1];
dp[nd][1] = vec[vec.size()-2];
}
}
void dfs(int nd, int pr, int t, int r){
vis[nd] = 1;
dpt[nd] = max(r, dp[nd][0].ff);
mx = max(mx, dpt[nd]);
cur[t] = min(cur[t], dpt[nd]);
for (auto i : E[nd]){
if (i.ff == pr) continue;
if (dp[nd][0].ss == i.ff) dfs(i.ff, nd, t, max(r+i.ss, dp[nd][1].ff+i.ss));
else dfs(i.ff, nd, t, max(r+i.ss, dp[nd][0].ff+i.ss));
}
}
int travelTime(int n, int m, int L, int A[], int B[], int T[]){
for (int i = 0; i < m; i++){
A[i]++;
B[i]++;
E[A[i]].pb({B[i], T[i]});
E[B[i]].pb({A[i], T[i]});
}
for (int i = 1; i <= n; i++){
if (!vis[i]) calc(i, 0, 0);
}
for (int i = 1; i <= n; i++){
vis[i] = 0;
cur[i] = 2e9+7;
}
int t=0;
for (int i = 1; i <= n; i++){
if (!vis[i]){
t++;
dfs(i, 0, t, 0);
}
}
vector<int> vec;
for (int i = 1; i <= t; i++) vec.pb(cur[i]);
sort(all(vec));
if (vec.size() == 1) return mx;
if (vec.size() == 2) return max(mx, vec[0]+vec[1]+L);
return max({mx, vec[vec.size()-1]+vec[vec.size()-2]+L, vec[vec.size()-2]+vec[vec.size()-3]+2*L});
}
// int main ()
// {
// ios::sync_with_stdio(false);
// cin.tie(0);
// int n, m, l;
// cin >> n >> m >> l;
// int A[m], B[m], T[m];
// for (int i = 0; i < m; i++) cin >> A[i] >> B[i] >> T[i];
// cout << travelTime(n, m, l, A, B, T);
// }
Compilation message
/usr/bin/ld: /tmp/cccrDWsT.o: in function `main':
grader.c:(.text.startup+0xd1): undefined reference to `travelTime'
collect2: error: ld returned 1 exit status
