mirror of
https://git.sb/baoshuo/OI-codes.git
synced 2024-11-27 16:36:28 +00:00
42 lines
948 B
C++
42 lines
948 B
C++
#pragma GCC optimize("Ofast")
|
|
|
|
#include <bits/stdc++.h>
|
|
|
|
using namespace std;
|
|
|
|
int n, m, ans;
|
|
bool f[405];
|
|
bitset<405> g[405];
|
|
pair<int, int> e[50005];
|
|
|
|
int main() {
|
|
std::ios::sync_with_stdio(false);
|
|
cin >> n >> m;
|
|
for (int i = 1; i <= m; i++) {
|
|
cin >> e[i].first >> e[i].second;
|
|
}
|
|
for (int i = 1; i <= n; i++) {
|
|
g[i][i] = true;
|
|
for (int j = m; j > 0; j--) {
|
|
if (g[i][e[j].first] && g[i][e[j].second]) {
|
|
f[i] = true;
|
|
break;
|
|
}
|
|
if (g[i][e[j].first] || g[i][e[j].second]) {
|
|
g[i][e[j].first] = g[i][e[j].second] = true;
|
|
}
|
|
}
|
|
}
|
|
for (int i = 1; i <= n; i++) {
|
|
if (!f[i]) {
|
|
for (int j = i + 1; j <= n; j++) {
|
|
if (!f[j] && !(g[i] & g[j]).count()) {
|
|
ans++;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
cout << ans << endl;
|
|
return 0;
|
|
}
|