Submission #572694

#	Time	Username	Problem	Language	Result	Execution time	Memory
572694		piOOE	Amusement Park (CEOI19_amusementpark)	C++17	0 / 100	1 ms	340 KiB

amusementpark

#include <bits/stdc++.h>

using namespace std;

#define sz(x) ((int)size(x))
#define all(x) begin(x), end(x)
#define trace(x) cout << #x << ": " << (x) << endl;

typedef long long ll;

mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

int rand(int l, int r) { return (int) ((ll) rnd() % (r - l + 1)) + l; }

const int N = 18, mod = 998244353;

int sum[1 << N], dp[1 << N];

vector<int> g[N], rg[N];
bool used[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        --a, --b;
        g[a].push_back(b);
        rg[b].push_back(a);
    }
    for (int mask = 1; mask < (1 << n); ++mask) {
        vector<int> now;
        memset(used, 0, sizeof(used));
        for (int i = 0; i < n; ++i) {
            if (mask & 1 << i) {
                used[i] = true;
                now.push_back(i);
            }
        }
        if (sz(now) == 1) {
            dp[mask] = 1;
            sum[mask] = 0;
        } else {
            bool none = true;
            for (int i: now) {
                int msk = mask ^ (1 << i);
                int cnt = 0;
                for (int to: rg[i]) {
                    if (used[to]) {
                        ++cnt;
                    }
                }
                if (cnt) {
                    dp[mask] = (dp[mask] + dp[msk]) % mod;
                    sum[mask] = (sum[mask] + sum[msk] + dp[msk] * (ll) cnt) % mod;
                    none = false;
                }
            }
            if (none) {
                dp[mask] = 1;
            }
        }
    }
    cout << sum[(1 << n) - 1];
    return 0;
}

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