Submission #1185418

#	Time	Username	Problem	Language	Result	Execution time	Memory
1185418		anmattroi	Rarest Insects (IOI22_insects)	C++17	25 / 100	71 ms	452 KiB

insects

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

using namespace std;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

vector<int> p;

int pressButton() {
    return press_button();
}

void moveInside(int i) {
    move_inside(p[i]);
}

void moveOutside(int i) {
    move_outside(p[i]);
}

int ok(int N, int X) {
    vector<int> A, B;

    for (int i = 0; i < N; i++) {
        moveInside(i);
        int T = pressButton();
        if (T >= X) {
            moveOutside(i);
            B.emplace_back(i);
        }
    }
    for (int i : B) {
        moveInside(i);
        int T = pressButton();
        if (T > X) {
            moveOutside(i);
            A.emplace_back(i);
        }
    }
    int diff = int(B.size()) - int(A.size());
    return diff * X < N - int(A.size());
}

int polySolution(int N) {
    for (int i = 0; i < N; i++) moveInside(i);
    vector<int> inside, outside;
    inside.resize(N);
    iota(inside.begin(), inside.end(), 0);
    while (1) {
        int X = pressButton();
        if (X == 1 || X == inside.size()) return X;
        for (int i : inside) {
            moveOutside(i);
            int T = pressButton();
            if (T == X) {
                moveOutside(i);
                outside.emplace_back(i);
            }
            else moveInside(i);
        }
        for (int i : inside)
            if (!binary_search(outside.begin(), outside.end(), i)) moveOutside(i);
        for (int i : outside) moveInside(i);
        swap(outside, inside);
        outside.clear();
    }
}

int min_cardinality(int N) {
    p.assign(N, 0);
    iota(p.begin(), p.end(), 0);
    shuffle(p.begin(), p.end(), rng);
    int lo = 1, hi = N+1;
    while (hi - lo > 1) {
        int mid = (lo + hi) >> 1;
        if (ok(N, mid)) hi = mid;
        else lo = mid;
        if (lo >= N/6) {
            return polySolution(N);
        }
        if (lo != hi) for (int i = 0; i < N; i++) moveOutside(i);
    }
    return lo;
}

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 0 / 75