Submission #705607

#	Time	Username	Problem	Language	Result	Execution time	Memory
705607		finn__	Amusement Park (CEOI19_amusementpark)	C++17	42 / 100	36 ms	564 KiB

amusementpark

#include <bits/stdc++.h>
using namespace std;

#define N 18
#define MOD 998244353

int64_t g[N], f[1 << N];
bitset<1 << N> is_independent;

int main()
{
    size_t n, m;
    cin >> n >> m;

    for (size_t i = 0; i < m; i++)
    {
        size_t u, v;
        cin >> u >> v;
        g[u - 1] ^= (1 << (v - 1));
        g[v - 1] ^= (1 << (u - 1));
    }

    for (size_t i = 0; i < 1U << n; i++)
    {
        is_independent[i] = 1;
        for (size_t j = 0; j < n; j++)
            if (i & (1 << j))
                is_independent[i] = is_independent[i] && !(g[j] & i);
    }

    f[0] = 1;
    for (size_t i = 0; i < 1U << n; i++)
    {
        for (size_t j = i; j; j = (j - 1) & i)
            if (is_independent[j])
                f[i] += f[i ^ j] * ((__builtin_popcount(j) & 1) ? 1 : -1);
        f[i] %= MOD;
    }

    cout << ((m * f[(1 << n) - 1] % MOD) * 499122177) % MOD << '\n';
}

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