Submission #1247838

#	Time	Username	Problem	Language	Result	Execution time	Memory
1247838		firegirlwaterboy	Amusement Park (CEOI19_amusementpark)	C++20	100 / 100	1983 ms	2764 KiB

amusementpark

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

const int MAXN = 1e6 + 5;
const ll MOD = 998244353;

int n, m, g[MAXN];
bool works[MAXN];
ll dp[MAXN];

void solve() {
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int x, y;
        cin >> x >> y;
        x--, y--;
        g[x] |= (1 << y), g[y] |= (1 << x);
    }
    for (int i = 0; i < (1 << n); i++) {
        works[i] = 1;
        for (int j = 1; j <= n; j++) {
            if (i >> j & 1) works[i] &= ((g[j] & i) == 0);
        }
    }
    dp[0] = 1;
    for (int i = 1; i < (1 << n); i++) {
        for (int j = i; j; j = (j - 1) & i) {
            if (!works[j]) continue;
            dp[i] += (__builtin_popcount(j) & 1 ? 1 : -1) * dp[i ^ j];
            (dp[i] += MOD) %= MOD;
        }
    }
    cout << dp[(1 << n) - 1] * m % MOD * (MOD + 1 >> 1) % MOD << "\n";
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
    return 0;
}

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