Submission #628148

#	Time	Username	Problem	Language	Result	Execution time	Memory
628148		I_love_Hoang_Yen	Rarest Insects (IOI22_insects)	C++17	47.50 / 100	193 ms	540 KiB

insects

#include "insects.h"
#include "bits/stdc++.h"

#define SZ(s) ((int) s.size())
using namespace std;

#ifndef RR
#define DEBUG(X)
#endif

/*
int min_cardinality(int n) {
    int res = n + 1;  // final result

    // used(i) = true if we already counted species of i
    std::vector<bool> used(n, false);
    for (int i = 0; i < n; ++i) {
        if (!used[i]) {
            // set containing all insects of this species
            std::set<int> same_species {i};
            move_inside(i);

            for (int j = i + 1; j < n; ++j) {
                if (!used[j]) {
                    move_inside(j);
                    if (press_button() == 1 + SZ(same_species)) {
                        same_species.insert(j);
                    } else {
                        move_outside(j);
                    }
                }
            }

            res = std::min(res, SZ(same_species));

            // remove all insects from machine
            for (int j : same_species) {
                move_outside(j);
                used[j] = true;
            }
        }
    }
    return res;
}
*/

int min_cardinality(int n) {
    std::set<int> insides;  // set of insects inside machine
    // lambda function to add one insect to machine
    auto add = [&] (int i) { move_inside(i); insides.insert(i); };
    // lambda function to remove one insect from machine
    auto remove = [&] (int i) { move_outside(i); insides.erase(i); };
    // lambda function to remove all insects from machine
    auto reset_machine = [&] () { auto ids = insides; for (int i : ids) remove(i); };

    // Step 1: Find set containing unique insects
    for (int i = 0; i < n; ++i) {
        add(i);
        if (press_button() > 1) {  // this species appeared before
            remove(i);
        }
    }
    int unique_vals = SZ(insides);
    reset_machine();

    // Step 2: Binary search for min f
    int l = 2, r = n / unique_vals, res = 1;
    while (l <= r) {
        int mid = (l + r) / 2;

        for (int i = 0; i < n; ++i) {
            add(i);
            if (press_button() > mid) remove(i);
        }
        int total = SZ(insides);
        reset_machine();

        if (total >= unique_vals * mid) {
            res = mid;
            l = mid + 1;
        } else {
            r = mid - 1;
        }
    }
    return res;
}

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 22.5 / 75