Submission #841162

#	Time	Username	Problem	Language	Result	Execution time	Memory
841162		peijar	Amusement Park (CEOI19_amusementpark)	C++17	100 / 100	1664 ms	608492 KiB

amusementpark

#include <bits/extc++.h> /** keep-include */
#include <bits/stdc++.h>
#define int long long
using namespace std;

string to_string(string s) { return s; }
template <typename T> string to_string(T v) {
  bool first = true;
  string res = "[";
  for (const auto &x : v) {
    if (!first)
      res += ", ";
    first = false;
    res += to_string(x);
  }
  res += "]";
  return res;
}

void dbg_out() { cout << endl; }
template <typename Head, typename... Tail> void dbg_out(Head H, Tail... T) {
  cout << ' ' << to_string(H);
  dbg_out(T...);
}

#ifdef DEBUG
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif

using ll = int;
// To use most bits rather than just the lowest ones:
struct chash { // large odd number for C
  const uint64_t C = ll(4e18 * acos(0)) | 71;
  ll operator()(ll x) const { return __builtin_bswap64(x * C); }
};

using hash_table = __gnu_pbds::gp_hash_table<int, int, chash>;

template <const int32_t MOD> struct ModInt {
  int32_t x;
  ModInt() : x(0) {}
  ModInt(long long u) : x(u % MOD) {
    if (x < 0)
      x += MOD;
  }
  friend bool operator==(const ModInt &a, const ModInt &b) {
    return a.x == b.x;
  }
  friend bool operator!=(const ModInt &a, const ModInt &b) {
    return a.x != b.x;
  }
  friend bool operator<(const ModInt &a, const ModInt &b) { return a.x < b.x; }
  friend bool operator>(const ModInt &a, const ModInt &b) { return a.x > b.x; }
  friend bool operator<=(const ModInt &a, const ModInt &b) {
    return a.x <= b.x;
  }
  friend bool operator>=(const ModInt &a, const ModInt &b) {
    return a.x >= b.x;
  }
  static ModInt sign(long long k) {
    return ((k & 1) ? ModInt(MOD - 1) : ModInt(1));
  }

  ModInt &operator+=(const ModInt &m) {
    x += m.x;
    if (x >= MOD)
      x -= MOD;
    return *this;
  }
  ModInt &operator-=(const ModInt &m) {
    x -= m.x;
    if (x < 0LL)
      x += MOD;
    return *this;
  }
  ModInt &operator*=(const ModInt &m) {
    x = (1LL * x * m.x) % MOD;
    return *this;
  }

  friend ModInt operator-(const ModInt &a) {
    ModInt res(a);
    if (res.x)
      res.x = MOD - res.x;
    return res;
  }
  friend ModInt operator+(const ModInt &a, const ModInt &b) {
    return ModInt(a) += ModInt(b);
  }
  friend ModInt operator-(const ModInt &a, const ModInt &b) {
    return ModInt(a) -= ModInt(b);
  }
  friend ModInt operator*(const ModInt &a, const ModInt &b) {
    return ModInt(a) *= ModInt(b);
  }

  static long long fp(long long u, long long k) {
    long long res = 1LL;
    while (k > 0LL) {
      if (k & 1LL)
        res = (res * u) % MOD;
      u = (u * u) % MOD;
      k /= 2LL;
    }
    return res;
  }

  static constexpr int mod() { return MOD; }

  ModInt fastpow(long long k) { return ModInt(fp(x, k)); }
  ModInt inv() {
    assert(x);
    return ModInt(fp(x, MOD - 2));
  }
  ModInt &operator/=(const ModInt &m) { return *this *= ModInt(m).inv(); }
  friend ModInt operator/(const ModInt &a, const ModInt &b) {
    return ModInt(a) *= ModInt(b).inv();
  }

  friend ostream &operator<<(ostream &out, const ModInt &a) {
    return out << a.x;
  }
  friend istream &operator>>(istream &in, ModInt &a) { return in >> a.x; }
  friend string to_string(ModInt u) { return to_string(u.x); }
};

// const int MOD = 1e9 + 7;
const int MOD = 998244353;
using Mint = ModInt<MOD>;

signed main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(0);

  int n, m;
  cin >> n >> m;
  vector<int> adj(n);
  vector<int> bitAdj(n);
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    --u, --v;
    adj[u] |= 1 << v;
    bitAdj[u] |= 1 << v;
    bitAdj[v] |= 1 << u;
  }

  vector<int> areBad(n);
  for (int u = 0; u < n; ++u)
    for (int v = 0; v < u; ++v)
      if (!((1 << v) & bitAdj[u]))
        areBad[u] |= 1 << v;
  vector<vector<pair<int, Mint>>> interesting(1 << n);

  interesting[0].emplace_back(0, 1);
  for (int added = 0; added < (1 << n); ++added) {
    sort(interesting[added].begin(), interesting[added].end());
    vector<pair<int, Mint>> compressed;
    for (auto [bad, ways] : interesting[added]) {
      if (compressed.empty() or compressed.back().first != bad)
        compressed.emplace_back(bad, 0);
      auto &[b, w] = compressed.back();
      w += ways;
    }
    int complement = (1 << n) - 1 - added;
    for (auto [bad, ways] : compressed) {
      for (int nxt = 0; nxt < n; ++nxt)
        if (!((1 << nxt) & added) and !((1 << nxt) & bad)) {
          int nxtBad = bad & (bad ^ bitAdj[nxt]);
          nxtBad |= areBad[nxt] & complement;
          interesting[added ^ (1 << nxt)].emplace_back(nxtBad, ways);
        }
    }
  }
  Mint sol = 0;
  for (auto [bad, ways] : interesting[(1 << n) - 1]) {
    assert(!bad);
    sol += ways;
  }
  cout << sol * m / 2 << endl;
}

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