Submission #641455

#	Time	Username	Problem	Language	Result	Execution time	Memory
641455		TimDee	Rarest Insects (IOI22_insects)	C++17	99.89 / 100	61 ms	432 KiB

insects

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

int n,d;
vector<int> in(2005,0);
vector<int> uniq;

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

int min_cardinality(int N) {
  n=N;
  d=0;

  vector<int> use; 
  for (int i=0; i<n; ++i) {
    use.push_back(i);
  }
  shuffle(use.begin(), use.end(),rng);

  for(int i=0; i<n; ++i) {
    move_inside(use[i]);
    int x=press_button();
    if (x>1) move_outside(use[i]);
    else { in[use[i]]=1; ++d; }
  }

  for (int i=0; i<n; ++i) if (in[i]) uniq.push_back(i);
  if (d==1) return n;
  if (d>n/2) return 1;
  if (d==2) {
    for (auto x:uniq) move_outside(x);
    int cnt=0;
    for (auto x:use) {
      move_inside(x);
      int X=press_button();
      if (X==cnt+1) ++cnt;
      else move_outside(x);
    }
    return min(cnt,n-cnt);
  }

  int l=1, r=n/d;
  int now=d;
  while (l<r) {
    vector<int> add;
    int mid=(l+r+1)>>1;
    int extra=0;
    int cnt=now;
    shuffle(use.begin(), use.end(),rng);
    for (auto x:use) {
      if (in[x]) continue;
      in[x]=1;
      move_inside(x);
      int X=press_button();
      if (X>mid) {
        extra=1;
        move_outside(x);
        in[x]=0;
      } else {
        ++cnt;
        add.push_back(x);
      }
    }
    if (cnt==mid*d) {
      if (extra==0) {
        return mid;
      } else {
        l=mid;
        now=cnt;
      }
    } else {
      now=cnt;
      r=mid-1;
      use=add;
      for (auto x:add) {
        --now;
        in[x]=0;
        move_outside(x);
      }
    }
  }
  return r;

}

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 74.89 / 75