Submission #572991

#	Time	Username	Problem	Language	Result	Execution time	Memory
572991		piOOE	Amusement Park (CEOI19_amusementpark)	C++17	100 / 100	1420 ms	2900 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 dp[1 << N], popc[1 << N];
bool ok[1 << N];

int add(int a, int b) {
    return a + b < MOD ? a + b : a + b - MOD;
}

int mul(int a, int b) {
    return a * (ll) b % MOD;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    memset(ok, 1, sizeof(ok));
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        --a, --b;
        ok[(1 << a) | (1 << b)] = false;
    }
    for (int mask = 1; mask < (1 << n); ++mask) {
        popc[mask] = __builtin_popcount(mask);
        for (int i = 0; i < n; ++i) {
            if ((mask & (1 << i)) && !ok[mask ^ (1 << i)]) {
                ok[mask] = false;
                break;
            }
        }
    }
    dp[0] = 1;
    for (int mask = 1; mask < (1 << n); ++mask) {
        for (int msk = mask; msk > 0; msk = (msk - 1) & mask) {
            if (!ok[msk]) {
                continue;
            }
            if (popc[msk] & 1) {
                dp[mask] = add(dp[mask], dp[mask ^ msk]);
            } else {
                dp[mask] = add(dp[mask], MOD - dp[mask ^ msk]);
            }
        }
    }
    cout << mul(dp[(1 << n) - 1], mul(m, (MOD + 1) >> 1));
    return 0;
}

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