Submission #1162468

#	Time	Username	Problem	Language	Result	Execution time	Memory
1162468		The_Samurai	Rarest Insects (IOI22_insects)	C++20	95.18 / 100	20 ms	436 KiB

insects

#include "insects.h"
#include "bits/stdc++.h"
using namespace std;
mt19937 rng(time(0));
int rand(int l, int r) {
    int x = rng(); x = abs(x);
    return x % (r - l + 1) + l;
}

int asked;

int min_cardinality(int n) {
    vector<int> ord(n);
    iota(ord.begin(), ord.end(), 0);
    for (int i = 1; i < n; i++) swap(ord[i], ord[rand(0, i)]);
    vector<bool> vis(n);
    vector<int> pos = {0};
    move_inside(0);

    for (int i = 1; i < n; i++) {
        move_inside(i);
        int x = press_button();
        if (x > 1) {
            move_outside(i);
        } else {
            pos.emplace_back(i);
        }
    }

    for (int x: pos) vis[x] = true;
    // int sq = min(n, 5 * (int) sqrt(n));
    if (pos.size() <= 7) {
        int ans = 1e9;
        for (int t = 0; t < pos.size(); t++) {
            int old = 1;
            vector<int> added;
            for (int i: ord) {
                if (vis[i]) continue;
                move_inside(i);
                int nw = press_button();
                if (nw == old) {
                    move_outside(i);
                } else {
                    added.emplace_back(i);
                    vis[i] = true;
                    old = nw;
                    // if (nw >= ans) break;
                }
            }
            for (int x: added) move_outside(x);
            ans = min(ans, old);
            if (ans == 1) break;
        }
        return ans;
    }
    if (pos.size() == 1) return n;
    if (pos.size() == n) return 1;
    auto ok = [&](int mid) -> bool {
        int cnt = count(vis.begin(), vis.end(), true);
        vector<int> added;
        for (int i: ord) {
            if (vis[i]) continue;
            move_inside(i);
            int now = press_button();
            if (now > mid) {
                move_outside(i);
            } else {
                added.emplace_back(i);
                cnt++;
            }
        }
        if (cnt == mid * pos.size()) {
            for (int x: added) vis[x] = true;
            return true;
        }

        for (int x: added) move_outside(x);
        ord = added;
        return false;
    };

    int lx = 2, rx = n / pos.size(), best = 1;
    while (lx <= rx) {
        int mid = (lx + rx) >> 1;
        if (ok(mid)) {
            best = mid;
            lx = mid + 1;
        } else {
            rx = mid - 1;
        }
    }
    return best;
}

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 70.18 / 75