Submission #1035545

#	Time	Username	Problem	Language	Result	Execution time	Memory
1035545		vjudge1	Political Development (BOI17_politicaldevelopment)	C++17	16 / 100	3105 ms	337784 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 = 9e2;

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

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

void clean(int x) {
  for (int i = 0; i < n; i++) {
    if (adj[i].size()+1 < x) r[i] = 1;
  }
}

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

  int sz = taken.count();
  if (sz > ans) {
    ans = sz;
    clean(sz+1);
  }

  shuffle(all(adj[x]), rng);
  for (int& y : adj[x]) { 
    if (c++ > X) return;
    if ((r[y] && sz+1 <= ans) || 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;
  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;
      st[i].insert(y);

      if (st[y].find(i) != st[y].end()) {
        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; i++) {
    if (r[vt[i]]) continue;

    c = 0;

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

    dfs(vt[i]);

    if (rng() % 2 == 0) r[vt[i]] = 1;
  }

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

Compilation message (stderr)

politicaldevelopment.cpp: In function 'void clean(int)':
politicaldevelopment.cpp:19:25: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   19 |     if (adj[i].size()+1 < x) r[i] = 1;
      |         ~~~~~~~~~~~~~~~~^~~
politicaldevelopment.cpp: In function 'void dfs(int)':
politicaldevelopment.cpp:35:71: warning: comparison of integer expressions of different signedness: 'std::size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   35 |     if ((r[y] && sz+1 <= ans) || 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