Submission #1114312

#	Time	Username	Problem	Language	Result	Execution time	Memory
1114312		n3rm1n	Amusement Park (CEOI19_amusementpark)	C++17	19 / 100	175 ms	13816 KiB

amusementpark

#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
const int MAXN = 12, MAXM = 200;
void speed()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}
int n, m;
int from[MAXM], to[MAXM];
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 int mod = 998244353;
unordered_set < long long > mp;
vector < int > g[MAXN];
void dfs(int beg)
{
    if(imp)return;
    visited[beg] = 1;
    in_cycle[beg] = 1;
    for (auto nb: g[beg])
    {
        if(imp)return;
        if(!visited[nb])dfs(nb);
        else if(in_cycle[nb])imp = 1;
    }
    in_cycle[beg] = 0;
}

void check()
{
    int cnt = 0;
    long long curr = 0;
    for (long long i = 1; i <= m; ++ i)
    {
        if(order[from[i]] > order[to[i]])
            curr = curr;
        else
            curr = curr + 1LL * (1 << (i-1));
    }
    if(mp.find(curr) != mp.end())return;
    mp.insert(curr);
    for (int i = 1; i <= n; ++ i)
    {
        g[i].clear();
        visited[i] = 0;
        in_cycle[i] = 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]);
        }
    }
    imp = 0;
    for (int i = 1; i <= n && (!imp); ++ 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;
}
/**
10 45
8 2
8 9
5 2
4 9
7 5
4 8
2 6
10 2
10 9
4 5
6 9
2 7
7 3
3 10
1 2
5 1
3 6
10 7
1 8
1 6
1 4
3 4
10 5
4 7
4 10
6 10
9 7
4 2
8 10
8 7
9 5
6 4
10 1
3 2
5 3
6 7
9 1
8 5
1 7
1 3
2 9
6 5
8 3
8 6
9 3



*/

• Subtask 1: 7 / 7
• Subtask 2: 12 / 12
• Subtask 3: 0 / 23
• Subtask 4: 0 / 21
• Subtask 5: 0 / 37