Submission #944752

#	Time	Username	Problem	Language	Result	Execution time	Memory
944752		nguyentunglam	Rarest Insects (IOI22_insects)	C++17	100 / 100	47 ms	1112 KiB

insects

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

const int NN = 1e5 + 10;

bool in[NN];

mt19937 rng(10184104810471);

int rnd(int l, int r) {
  return l + rng() % (r - l + 1);
}

int min_cardinality(int n) {
  int type = 0;
  vector<int> candidate;
  for(int i = 0; i < n; i++) {
    move_inside(i);
    if (press_button() == 1) {
      ++type;
      in[i] = 1;
    }
    else {
      move_outside(i);
      candidate.push_back(i);
    }
  }

  int l = 2, r = n / type, ans = 1;
  int cur = 1;

  while (l <= r) {
    shuffle(candidate.begin(), candidate.end(), rng);
    int mid = type <= 75 ? (l + r + 1) / 2 : (l + r) / 2;
    assert(cur <= mid);
    int last = cur;
    for(auto &i : candidate) {
      move_inside(i);
      int nxt = press_button();
      if (nxt > mid) {
        move_outside(i);
        in[i] = 0;
      }
      else {
        cur = nxt;
        in[i] = 1;
      }
    }
    int total = 0;
    for(int i = 0; i < n; i++) total += in[i];
    vector<int> _candidate;

    if (cur == mid && mid * type == total) {
      for(auto &i : candidate) if (!in[i]) _candidate.push_back(i);
      l = mid + 1;
      ans = mid;
    }
    else {
      for(auto &i : candidate) if (in[i]) {
        _candidate.push_back(i);
        move_outside(i);
        in[i] = 0;
      }
      r = mid - 1;
      cur = last;
    }
    candidate = _candidate;
  }
  return ans;
}

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