#include<bits/stdc++.h> //:3
using namespace std;
typedef long long ll;
#define all(a) (a).begin(), (a).end()
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define pi pair<int, int>
#define sz(x) (int)((x).size())
//#define int long long
const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};
const ll inf = 2e9;
const ll mod = 1e9 + 7;
const int N = 2e5 + 11;
const int X = 1e6;
const ll INF64 = 3e18 + 1;
const double eps = 1e-14;
const double PI = acos(-1);
//ifstream in(".in");
//ofstream out(".out");
int path[N], viz[N], s[N], dp_up[N], dp_down[N], nr;
vector<pi> v[N];
vector<int> c[N];
void dfs(int nod, int P){
c[nr].pb(nod);
viz[nod] = 1;
for(auto it : v[nod]){
if(it.ff == P)continue;
s[nod] = max(s[nod], s[it.ff] + it.ss);
}
int mx1 = 0, mx2 = 0;
for(auto it : v[nod]){
if(it.ff == P)continue;
if(s[it.ff] + it.ss > mx1){
mx2 = mx1;
mx1 = s[it.ff] + it.ss;
continue;
}
if(s[it.ff] + it.ss > mx2){
mx2 = s[it.ff] + it.ss;
continue;
}
}
dp_down[nod] = mx1 + mx2;
}
void dfs2(int nod, int P, int cost){
dp_up[nod] = max(dp_up[nod], dp_up[P] + cost);
int mx1 = 0, mx2 = 0, F = 0;
for(auto it : v[nod]){
if(it.ff == P)continue;
if(s[it.ff] + it.ss > mx1){
mx2 = mx1;
mx1 = s[it.ff] + it.ss;
F = it.ff;
continue;
}
if(s[it.ff] + it.ss > mx2){
mx2 = s[it.ff] + it.ss;
continue;
}
}
for(auto it : v[nod]){
if(it.ff == P)continue;
if(it.ff == F){
dp_up[it.ff] = max(dp_up[it.ff], mx2 + it.ss);
continue;
}
dp_up[it.ff] = max(dp_up[it.ff], mx1 + it.ss);
}
for(auto it : v[nod]){
if(it.ff == P)continue;
dfs2(it.ff, nod, it.ss);
}
}
int travelTime (int n, int m, int l, int a[], int b[], int cost[]){
for(int i = 0; i <= n; i++){
v[i].clear();
}
for(int i = 0; i < m; i++){
int x = a[i], y = b[i], z = cost[i];
x++, y++;
v[x].push_back({y, z});
v[y].push_back({x, z});
}
memset(viz,0,sizeof(viz));
memset(dp_up,0,sizeof(dp_up));
memset(dp_down,0,sizeof(dp_down));
memset(s,0,sizeof(s));
int nr_comp = 0;
for(int i = 1; i <= n; i++){
if(viz[i])continue;
nr_comp++;
dfs(i, 0);
dfs2(i, 0, 0);
}
int ans = 0;
for(int i = 1;i <= nr; i++){
int mn = inf;
for(auto nod : c[i]){
int dist_max = max(dp_up[nod] + s[nod], dp_down[nod]);
ans = max(ans, dist_max);
int dist = max(s[nod], dp_up[nod]);
mn = min(mn,dist);
}
path[i] = mn;
}
sort(path + 1, path + nr + 1);
if(nr >= 2)ans = max(ans, path[nr] + path[nr - 1] + l);
if(nr >= 3)ans = max(ans, path[nr - 1] + path[nr - 2] + 2*l);
return ans;
}
Compilation message
/tmp/ccTmfRha.o: In function `main':
grader.c:(.text.startup+0xa7): undefined reference to `travelTime'
collect2: error: ld returned 1 exit status
