#include <bits/stdc++.h>
#include"dreaming.h"
using namespace std;
#define ll long long
#define endl '\n'
const int N = 1e5 + 5;
ll dp[N], res, vis[N], vis2[N], diameter;
vector<pair<ll, ll>> node[N];
void dfsFirst(ll u){
vis[u] = 1;
for (auto j : node[u]){
if (vis[j.first]) continue;
dfsFirst(j.first);
dp[u] = max(dp[u], dp[j.first] + j.second);
}
}
void reroot(ll u, ll v){
dp[u] = 0;
for (auto j : node[u]){
if (j.first == v) continue;
dp[u] = max(dp[u], dp[j.first] + j.second);
}
dp[v] = 0;
for (auto j : node[v]){
dp[v] = max(dp[v], dp[j.first] + j.second);
}
if (res >= dp[v]){
res = min(res, dp[v]);
vector<ll> mem;
for (auto j : node[v]){
mem.push_back(dp[j.first] + j.second);
}
diameter = 0;
if (mem.size()){
sort(mem.begin(), mem.end());
for (int i = mem.size() - 1; i >= max((ll)mem.size() - 2, 0ll); i--){
diameter += mem[i];
}
}
}
}
void dfs(ll u, ll p){
for (auto j : node[u]){
if (j.first == p) continue;
reroot(u, j.first);
dfs(j.first, u);
reroot(j.first, u);
}
}
int travelTime(int N, int M, int L, vector<int> A, vector<int> B, vector<int> T){
for (int i = 1; i <= M; i++){
node[A[i - 1]].push_back({B[i - 1], T[i - 1]});
node[B[i - 1]].push_back({A[i - 1], T[i - 1]});
}
priority_queue<ll> pq;
ll ans = 0;
for (int i = 1; i <= N; i++){
if (!vis[i]){
diameter = 0;
dfsFirst(i);
res = dp[i];
dfs(i, i);
ans = max(ans, diameter);
pq.push(res);
}
}
ll root = pq.top();
pq.pop();
ll mx = -1e18;
ll res = root;
while (pq.size()){
ans = max(ans, pq.top() + 2 * L + mx);
ans = max(ans, pq.top() + L + root);
mx = max(mx, pq.top());
pq.pop();
}
return ans;
}
/*
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
if (fopen("VietCT.INP", "r")){
freopen("VietCT.INP", "r", stdin);
freopen("VietCT.OUT", "w", stdout);
}
int n, m, l;
cin >> n >> m >> l;
vector<int> a, b, t;
for (int i = 1; i <= m; i++){
int u, v, c;
cin >> u >> v >> c;
a.push_back(u + 1);
b.push_back(v + 1);
t.push_back(c);
}
cout << travelTime(n, m, l, a, b, t);
}
*/
/*
12 8 2
0 8 4
8 2 2
2 7 4
5 11 3
5 1 7
1 3 1
1 9 5
10 6 3
*/
Compilation message
dreaming.cpp: In function 'int travelTime(int, int, int, std::vector<int>, std::vector<int>, std::vector<int>)':
dreaming.cpp:72:12: warning: unused variable 'res' [-Wunused-variable]
72 | ll res = root;
| ^~~
/tmp/cc4zJ5P1.o: In function `main':
grader.c:(.text.startup+0xa7): undefined reference to `travelTime'
collect2: error: ld returned 1 exit status
