Submission #627645

#	Time	Username	Problem	Language	Result	Execution time	Memory
627645		I_love_Hoang_Yen	Rarest Insects (IOI22_insects)	C++17	93.70 / 100	95 ms	556 KiB

insects

#include "insects.h"
#include "bits/stdc++.h"
#define SZ(s) ((int) s.size())
using namespace std;

#ifndef RR
#define DEBUG(X)
#endif

/* sub1
// Sub 1 {{{
int min_cardinality(int n) {
    std::vector<int> v_ids(n);
    std::iota(v_ids.begin(), v_ids.end(), 0);

    std::set<int> ids(v_ids.begin(), v_ids.end());
    int freq = 0, last_cnt = 0;

    while (true) {
        ++freq;
        std::set<int> new_ids;

        for (int id : ids) {
            move_inside(id);
            if (press_button() > freq) {
                move_outside(id);
                new_ids.insert(id);
            }
        }

        int unique_values = SZ(ids) - SZ(new_ids);
        if (unique_values < last_cnt) {
            return freq - 1;
        }
        last_cnt = unique_values;

        if (unique_values > SZ(new_ids)) {
            return freq;
        }

        ids = std::move(new_ids);
    }

    return 0;
}
// }}}
*/

// seeds = set containing unique indices
int solve_small(int n, const std::set<int>& seeds) {
    std::set<int> used;
    int res = n;

    int n_unique = SZ(seeds);
    for (int turn = 0; turn + 1 < n_unique; ++turn) {
        std::set<int> cur;

        for (int i = 0; i < n; ++i) {
            if (!seeds.count(i) && !used.count(i)) {
                cur.insert(i);
                move_inside(i);

                if (press_button() != SZ(cur) + 1) {
                    move_outside(i);
                    cur.erase(i);
                }
            }
        }

        used.insert(cur.begin(), cur.end());
        res = std::min(res, SZ(cur) + 1);

        for (int i : cur) move_outside(i);
    }

    int remaining = n - SZ(used) - SZ(seeds) + 1;
    res = std::min(res, remaining);

    return res;
}

int min_cardinality(int n) {
    std::set<int> insides;
    int freq = 1;

    auto add = [&] (int i) {
        insides.insert(i);
        move_inside(i);
    };
    auto remove = [&] (int i) {
        insides.erase(i);
        move_outside(i);
    };

    for (int i = 0; i < n; ++i) {
        add(i);
        if (press_button() > 1) {
            remove(i);
        }
    }
    int unique_vals = SZ(insides);
    DEBUG(unique_vals);

    auto save_ids = insides;

    if (unique_vals <= 5) {
        return solve_small(n, insides);
    }

    int l = 2, r = n / unique_vals, res = 1;
    while (l <= r) {
        int mid = l + (r - l + 1) / 2;

        assert(mid != freq);
        if (mid > freq) {
            for (int i = 0; i < n; ++i) {
                if (!insides.count(i)) {
                    add(i);
                    if (press_button() > mid) {
                        remove(i);
                    }
                }
            }
        } else {
            auto ids = insides;
            for (int id : save_ids) ids.erase(id);

            for (int id : ids) remove(id);

            for (int i : ids) {
                add(i);
                if (press_button() > mid) {
                    remove(i);
                }
            }
        }
        freq = mid;
        int total = SZ(insides);

        if (total >= unique_vals * mid) {
            save_ids = insides;

            // all values have at least frequency = mid
            res = mid;
            l = mid + 1;
        } else {
            r = mid - 1;
        }
    }
    return res;
}

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 68.7 / 75