#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
const int MAXN = 20;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
int n, m;
int from[MAXN], to[MAXN];
void read()
{
cin >> n >> m;
for (int i = 1; i <= m; ++ i)
cin >> from[i] >> to[i];
}
int order[MAXN], used[MAXN], visited[MAXN], in_cycle[MAXN]; /// na koq poziciq e i
long long ans = 0, imp = 0;
const long long mod = 998244353;
vector < int > g[MAXN];
void dfs(int beg)
{
visited[beg] = 1;
in_cycle[beg] = 1;
for (auto nb: g[beg])
{
if(!visited[nb])dfs(nb);
else if(in_cycle[nb])imp = 1;
}
in_cycle[beg] = 0;
}
void check()
{
for (int i = 1; i <= n; ++ i)
g[i].clear();
int cnt = 0;
for (int i = 1; i <= m; ++ i)
{
if(order[from[i]] > order[to[i]])
g[from[i]].push_back(to[i]);
else
{
cnt ++;
g[to[i]].push_back(from[i]);
}
}
memset(visited, 0, sizeof(visited));
memset(in_cycle, 0, sizeof(in_cycle));
imp = 0;
for (int i = 1; i <= n; ++ i)
{
if(visited[order[i]])continue;
dfs(visited[order[i]]);
}
if(imp)return;
ans += cnt;
ans %= mod;
}
void gen(int pos)
{
if(pos > n)
{
check();
return;
}
for (int i = 1; i <= n; ++ i)
{
if(used[i])continue;
order[pos] = i;
used[i] = 1;
gen(pos+1);
used[i] = 0;
}
}
int main()
{
speed();
read();
gen(1);
cout << ans << endl;
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
1 ms |
336 KB |
Output is correct |
3 |
Incorrect |
1 ms |
336 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
1 ms |
336 KB |
Output is correct |
3 |
Incorrect |
1 ms |
336 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
1 ms |
336 KB |
Output is correct |
3 |
Incorrect |
1 ms |
336 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
1 ms |
336 KB |
Output is correct |
3 |
Incorrect |
1 ms |
336 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
336 KB |
Output is correct |
2 |
Correct |
1 ms |
336 KB |
Output is correct |
3 |
Incorrect |
1 ms |
336 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |