이 제출은 이전 버전의 oj.uz에서 채점하였습니다. 현재는 제출 당시와는 다른 서버에서 채점을 하기 때문에, 다시 제출하면 결과가 달라질 수도 있습니다.
#include <vector>
#include <iostream>
#include <set>
#include <bitset>
#include <algorithm>
using namespace std;
int n;
vector< vector<short> > g, tg;
vector< bitset<5001> > mat;
vector<int> was, topoSort, scc;
vector<int> index, lowlink, s;
int cur = 1, gi = 1;
vector<int> as;
vector<int> st;
vector<short> x[2];
int cnt[2][2];
void add_edge(int u, int v) {
g[u].push_back(v);
}
void strongconnect(int u) {
index[u] = gi;
lowlink[u] = gi;
gi++;
s.push_back(u);
was[u] = 2;
for (auto& v : g[u]) {
if (!was[v]) {
strongconnect(v);
lowlink[u] = min(lowlink[v], lowlink[u]);
}
else if (was[v] == 2) {
lowlink[u] = min(lowlink[u], index[v]);
}
}
if (lowlink[u] == index[u]) {
while (true) {
int w = s.back();
s.pop_back();
scc[w] = cur;
if (w == u) break;
}
cur++;
}
was[u] = 1;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n;
mat.assign(n + 1, bitset<5001>());
g.resize(2 * n + 1);
for (int i = 1; i <= n; i++) {
int k;
cin >> k;
while (k--) {
int a;
cin >> a;
mat[a][i] = mat[i][a] = 1;
}
}
for (int i = 1; i <= n - 1; i++) {
for (int j = i + 1; j <= n; j++) {
if (mat[i][j]) {
add_edge(i, j + n);
add_edge(j, i + n);
}
else {
add_edge(i + n, j);
add_edge(j + n, i);
}
}
}
was.assign(2 * n + 1, 0);
scc.assign(2 * n + 1, -1);
index.assign(2 * n + 1, 0);
lowlink.assign(2 * n + 1, 0);
for (int i = 1; i <= 2 * n; i++) {
if (!was[i]) {
strongconnect(i);
}
}
as.resize(n + 1);
for (int i = 1; i <= n; i++) {
if (scc[i] == scc[i + n]) {
cout << 0 << '\n';
return 0;
}
as[i] = scc[i] < scc[i + n];
}
int ans = 1;
int sup = 0, con = 0;
for (int i = 1; i <= n; i++) {
sup += 1 - as[i];
con += as[i];
x[1 - as[i]].push_back(i);
}
if ((sup == 0) || (con == 0)) {
ans = 0;
}
st.resize(n + 1);
for (auto& u : x[0]) {
for (auto& v : x[1]) {
int idx = mat[u][v] ? v : u;
int idx2 = mat[u][v] ? u : v;
if (st[idx] > 0) {
st[idx] = -1;
} else if (st[idx] == 0) {
st[idx] = idx2;
}
}
}
for (int i = 1; i <= n; i++) {
if (st[i] == 0) {
if ((as[i]) && (con > 1)) ans++;
if ((!as[i]) && (sup > 1)) ans++;
}
}
for (int i = 0; i < 2; i++) {
for (auto& u : x[i]) {
if (st[u] == 0) {
cnt[i][0]++;
}
else if (st[u] > 0) {
cnt[i][1]++;
}
}
}
ans += cnt[0][0] * cnt[1][1] + cnt[0][1] * cnt[1][0];
cout << ans << '\n';
return 0;
}
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