Submission #1222076

#	Time	Username	Problem	Language	Result	Execution time	Memory
1222076		_callmelucian	Amusement Park (CEOI19_amusementpark)	C++17	42 / 100	11 ms	4676 KiB

amusementpark

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

using ll = long long;
using ld = long double;
using pl = pair<ll,ll>;
using pii = pair<int,int>;
using tpl = tuple<int,int,int>;

#define all(a) a.begin(), a.end()
#define filter(a) a.erase(unique(all(a)), a.end())

const int MOD = 998'244'353;
bitset<19> adj[19];
int dp[1 << 10][1 << 10], n, m;

bool getCur (int mask, int pos) {
    return mask >> pos & 1;
}

int add (int a, int b) { return a + b - (a + b < MOD ? 0 : MOD); }
int sub (int a, int b) { return a - b + (a - b >= 0 ? 0 : MOD); }
int mul (int a, int b) { return 1LL * a * b % MOD; }

int binpow (int a, int b) {
    int ans = 1;
    for (; b; b >>= 1, a = mul(a, a))
        if (b & 1) ans = mul(ans, a);
    return ans;
}

const int inv2 = binpow(2, MOD - 2);

bool selfIntersect (int mask) {
    for (int i = 0; i < n; i++) {
        if (getCur(mask, i) && (adj[i] & bitset<19>(mask)).count()) return 1;
    }
    return 0;
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int a, b; cin >> a >> b;
        a--, b--;
        adj[a][b] = adj[b][a] = 1;
    }

    for (int mask = 0; mask < (1 << n); mask++) {
        for (int sub = mask; sub; sub = (sub - 1) & mask) {
            int last = mask ^ sub;
            if (selfIntersect(last)) continue;
            for (int preLast = sub;; preLast = (preLast - 1) & sub) {
                bool flag = 1;
                for (int i = 0; i < n; i++)
                    if (getCur(preLast, i) && !(adj[i] & bitset<19>(last)).count()) { flag = 0; break; }
                if (flag) dp[mask][last] = add(dp[sub][preLast], dp[mask][last]);
                if (!preLast) break;
            }
        }
        dp[mask][mask] = !selfIntersect(mask);
    }

    int ans = 0;
    for (int mask = 0; mask < (1 << n); mask++)
        ans = add(ans, dp[(1 << n) - 1][mask]);

    cout << mul(mul(ans, inv2), m);

    return 0;
}

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