Submission #643667

#	Time	Username	Problem	Language	Result	Execution time	Memory
643667		Vanilla	Rarest Insects (IOI22_insects)	C++17	50 / 100	197 ms	336 KiB

insects

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

int min_cardinality(int n) {
  unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();
  std::default_random_engine rng(seed);
  vector <bool> tr (n);
  int tp = 0;
  for (int i = 0; i < n; i++){
    move_inside(i);
    if (press_button() == 2) {
      move_outside(i);
    }
    else {
      tr[i] = 1;
      tp++;
    }
  }
  for (int i = 0; i < n; i++) if (tr[i]) move_outside(i);
  int l = 0, r = n / tp, rs = -1;
  int btn = 0;
  vector <int> in (n);
  while (l <= r){
    int mid = (l + r) / 2;
    auto check = [&] (int x) -> bool {
      int ins = btn;
      vector <int> vis (n);
      vector <int> ord (n);
      iota(ord.begin(), ord.end(), 0);
      shuffle(ord.begin(), ord.end(), rng);
      for (int i: ord) {
        if (in[i]) continue;
        move_inside(i);
        if (press_button() > x) {
          move_outside(i);
        }
        else {
          ins++;
          vis[i] = in[i] = 1;
        }
      }
      if (ins != x * tp) {
        for (int i = 0; i < n; i++) 
          if (vis[i]) {
            in[i] = 0;
            move_outside(i);
          }
        return 0;
      }
      else {
        btn = ins;
        return 1;
      }
    };
    if (check(mid)) {
      rs = mid;
      l = mid + 1;
    }
    else {
      r = mid - 1;
    }
  }
  return rs;
}

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 25 / 75