Submission #794445

#	Time	Username	Problem	Language	Result	Execution time	Memory
794445		IvanJ	Rarest Insects (IOI22_insects)	C++17	97.90 / 100	60 ms	456 KiB

insects

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

#define pb push_back
#define x first
#define y second
#define all(a) (a).begin(), (a).end()

using namespace std;

typedef long long ll;
typedef pair<int, int> ii;

mt19937 rng(1209747089);
const int maxn = 2005;

int n, D, step;
int vis[maxn];
int forb[maxn];
vector<ii> in;
vector<int> p;

int check(int x) {
	int y = -1, lst = 0;
	int num = 0;
	for(int i = 0;i < n;i++) num += !(forb[i] | vis[i]);
	shuffle(all(p), rng);
	for(int i : p) {
		if(vis[i] || forb[i]) continue;
		num--;
		move_inside(i);
		int cnt = press_button();
		if(lst < x && cnt == x) y = i;
		if(cnt > x) 
			move_outside(i), forb[i] = 1;
		else in.pb({i, step}), vis[i] = 1;
		if((int)in.size() == x * D) return 1;
		lst = cnt;
		if((int)in.size() + num < x * D) break;
	}
	if(y != -1) forb[y] = 1;
	return 0;
}

int min_cardinality(int N) {
	srand(time(0));
	n = N, D = 0, step = 1;
	
	for(int i = 0;i < n;i++) p.pb(i);
	shuffle(all(p), rng);
	
	for(int i : p) {
		move_inside(i);
		if(press_button() > 1) 
			move_outside(i);
		else in.pb({i, step}), vis[i] = 1, D++;
	}
	
	int lo = 1, hi = n / D, ans = 1;
	while(lo <= hi) {
		step++;
		int mid = (lo + hi) / 2;
		int num = 0;
		for(int i = 0;i < n;i++) num += !(forb[i] | vis[i]);
		if((num / D) < (mid - ans)) {hi = mid - 1;continue;}
		int flag = check(mid);
		if(flag) {
			ans = mid, lo = mid + 1;
			for(int i = 0;i < n;i++) forb[i] = 0;
		} else {
			hi = mid - 1;
			while(in.back().y == step)
				move_outside(in.back().x), vis[in.back().x] = 0, in.pop_back();
		}
	}
	return ans;
}

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 72.9 / 75