Submission #572963

#	Time	Username	Problem	Language	Result	Execution time	Memory
572963		piOOE	Amusement Park (CEOI19_amusementpark)	C++17	100 / 100	1556 ms	234720 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 adj[N];

map<int, int> dp[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);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        --a, --b;
        adj[a] |= (1 << b);
        adj[b] |= (1 << a);
    }
    dp[0][(1 << n) - 1] = 1;
    for (int a = 0; a < (1 << n); ++a) {
        for (auto [b, cnt] : dp[a]) {
            for (int i = 0; i < n; ++i) {
                if (b & 1 << i) {
                    int newb = b & (1 << n) - (1 << (i + 1));
                    newb = newb | ((adj[i] | a) ^ a);
                    dp[a ^ (1 << i)][newb] = add(dp[a ^ (1 << i)][newb], cnt);
                }
            }
        }
    }
    cout << mul(dp[(1 << n) - 1][0], mul(m, (MOD + 1) / 2));
    return 0;
}

Compilation message (stderr)

amusementpark.cpp: In function 'int main()':
amusementpark.cpp:46:45: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   46 |                     int newb = b & (1 << n) - (1 << (i + 1));
      |                                    ~~~~~~~~~^~~~~~~~~~~~~~~~

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