Submission #1035434

#	Time	Username	Problem	Language	Result	Execution time	Memory
1035434		vjudge1	Political Development (BOI17_politicaldevelopment)	C++17	16 / 100	1637 ms	524288 KiB

politicaldevelopment

#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector,fast-math,inline")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,lzcnt,mmx,abm,avx,avx2,fma")
#include <bits/stdc++.h>
using namespace std;

#define all(x) x.begin(), x.end()

const int N = 5e4, /*X = 5e5, */X2 = 5e2;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n, k, c, ans;
vector<int> vt, adj[N];
bitset<N> bt[N], bt2[N], taken, toTake;

void dfs2(int x) {
  if (c++ > X2) return;

  int sz = taken.count();
  ans = max(ans, sz);
  
  shuffle(all(adj[x]), rng);
  for (int& y : adj[x]) { 
    if (c++ > X2) return;
    if (!taken[y] && (taken & bt2[y]).count() < sz) continue;

    taken[y] = 1;
    bitset<N> toTakePrev = toTake;
    toTake &= bt2[y];

    dfs2(y);
    if (c++ > X2) return;

    toTake = toTakePrev;
    taken[y] = 0;
  }
}

/*
void dfs(int x) {
  if (c++ > X) return;

  int sz = taken.count();
  ans = max(ans, sz);

  shuffle(all(adj[x]), rng);
  for (int& y : adj[x]) {
    if (c++ > X) return;
    if (!taken[y] && (taken & bt2[y]).count() < sz) continue;

    taken[y] = 1;
    bitset<N> toTakePrev = toTake;
    toTake &= bt2[y];

    dfs(y);
    if (c++ > X) return;

    toTake = toTakePrev;
    taken[y] = 0;
  }
}
*/

signed main() {
  ios::sync_with_stdio(false); cin.tie(nullptr);

  cin >> n >> k;
  //c = 0;
  ans = 1;
  vt.resize(n);
  for (int i = 0; i < n; i++) {
    vt[i] = i;
    bt2[i][i] = toTake[i] = 1;

    int x; cin >> x;
    for (int j = 0; j < x; j++) {
      int y; cin >> y;
      bt[i][y] = 1;

      if (bt[y][i]) {
        bt2[i][y] = 1;
        adj[i].push_back(y);

        bt2[y][i] = 1;
        adj[y].push_back(i);
      }
    }
  }

/*
  shuffle(all(vt), rng);
  for (int i = 0; i < n && c < X; i++) {
    dfs(vt[i]);
  }
  */

  shuffle(all(vt), rng);
  for (int i = 0; i < n; i++) {
    c = 0;

    taken.reset();
    taken[vt[i]] = 1;
    toTake = bt2[vt[i]];

    dfs2(vt[i]);
  }

  cout << ans << "\n";
}

Compilation message (stderr)

politicaldevelopment.cpp: In function 'void dfs2(int)':
politicaldevelopment.cpp:25:47: warning: comparison of integer expressions of different signedness: 'std::size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   25 |     if (!taken[y] && (taken & bt2[y]).count() < sz) continue;
      |                      ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 0 / 23
• Subtask 4: 0 / 38
• Subtask 5: 0 / 23