Submission #1088384

#	Time	Username	Problem	Language	Result	Execution time	Memory
1088384		abczz	Rarest Insects (IOI22_insects)	C++17	99.89 / 100	46 ms	856 KiB

insects

#include "insects.h"
#include <iostream>
#include <vector>
#include <random>
#define ll long long

using namespace std;

random_device rd;
mt19937 mt(rd());
int min_cardinality(int N) {
  vector <ll> V, X, A, B;
  ll s = 0, a, b, mid, f = 1;
  for (int i=0; i<N; ++i) {
    move_inside(i);
    auto res = press_button();
    if (res > 1) {
      move_outside(i);
      X.push_back(i);
    }
    else V.push_back(i);
  }
  for (auto u : V) move_outside(u);
  s = V.size();
  while (true) {
    A.clear();
    B.clear();
    if (X.size() < s) return f;
    a = (X.size() / s) / 2;
    a = max(a, 1LL);
    b = a+1;
    b = min(b, (ll)X.size()/s);
    if (abs(a*s-(ll)X.size()/2) > abs(b*s-(ll)X.size()/2) || mt() % 4 == 3) mid = b;
    else mid = a;
    ll p = -1;
    for (auto u : X) {
      move_inside(u);
      auto res = press_button();
      if (res == mid && p == -1) p = u;
      if (res > mid) {
        B.push_back(u);
        move_outside(u);
      }
      else A.push_back(u);
    }
    for (auto u : A) move_outside(u);
    if (A.size() == mid * s) {
      swap(X, B);
      f += mid;
    }
    else {
      swap(X, A);
      for (int i=0; i<X.size(); ++i) {
        if (X[i] == p) {
          swap(X[i], X.back());
          X.pop_back();
          break;
        }
      }
    }
  }
}

Compilation message (stderr)

insects.cpp: In function 'int min_cardinality(int)':
insects.cpp:28:18: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
   28 |     if (X.size() < s) return f;
      |         ~~~~~~~~~^~~
insects.cpp:47:18: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
   47 |     if (A.size() == mid * s) {
      |         ~~~~~~~~~^~~~~~~~~~
insects.cpp:53:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |       for (int i=0; i<X.size(); ++i) {
      |                     ~^~~~~~~~~

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