// IOI 2013 - Dreaming
// Lúcio Cardoso
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5+10;
typedef pair<int, int> pii;
int pai[MAXN], dist[MAXN], comp[MAXN], n, m, l, ind, maior;
bool mark[MAXN];
vector<pii> grafo[MAXN];
void DFS(int u, int p, int c)
{
comp[c] = u, mark[u] = 1;
for (auto v: grafo[u])
{
if (v.first == p) continue;
DFS(v.first, u, c);
}
}
void DFS2(int u, int p, int d)
{
for (auto v: grafo[u])
{
if (v.first == p) continue;
dist[v.first] = d+v.second;
if (dist[v.first] > maior)
maior = dist[v.first], ind = v.first;
pai[v.first] = u;
DFS2(v.first, u, dist[v.first]);
}
}
int travelTime(int N, int M, int L, int A[], int B[], int T[])
{
n = N, m = M, l = L;
for (int i = 0; i < m; i++)
grafo[A[i]].push_back({B[i], T[i]}), grafo[B[i]].push_back({A[i], T[i]});
int c = -1;
for (int i = 0; i < n; i++)
if (!mark[i])
DFS(i, -1, ++c);
int maxdiam = 0, m1 = 0, m2 = 0, m3 = 0;
for (int i = 0; i <= c; i++)
{
maior = 0, ind = comp[i];
int u = comp[i];
DFS2(u, -1, 0);
u = ind;
maior = 0, ind = comp[i];
dist[u] = 0, pai[u] = -1;
DFS2(u, -1, 0);
maxdiam = max(maxdiam, maior);
int v = ind, diam = maior, ans = maior;
while (v != -1)
{
if (max(dist[v], diam-dist[v]) < ans)
ans = max(dist[v], diam-dist[v]);
v = pai[v];
}
if (ans >= m1) m3 = m2, m2 = m1, m1 = ans;
else if (ans >= m2) m3 = m2, m2 = ans;
else if (ans >= m3) m3 = ans;
}
if (c == 0) return maxdiam;
else if (c == 1) return max(maxdiam, m1+m2+l);
return max(maxdiam, max(m1+m2+l, m2+m3+2*l));
}
Compilation message
/tmp/cc6b2Gqv.o: In function `main':
grader.c:(.text.startup+0xa2): undefined reference to `travelTime'
collect2: error: ld returned 1 exit status
