Submission #1210085

#	Time	Username	Problem	Language	Result	Execution time	Memory
1210085		That_Salamander	Counting Mushrooms (IOI20_mushrooms)	C++20	80.71 / 100	3 ms	528 KiB

mushrooms

#include "mushrooms.h"

#include <algorithm>
#include <random>

using namespace std;

/*
2 * START + (n - 2 * START) / (START - 1)
*/

int count_mushrooms(int n) {
	vector<int> knownAs, knownBs;
	knownAs.push_back(0);

	int pos = 1;
	int res = knownAs.size();

	vector<int> perm(n);
	for (int i = 0; i < n; i++) perm[i] = i;

	mt19937 rng(7);
	shuffle(perm.begin() + 1, perm.end(), rng);

	while (pos < n) {
		int querySize = max(knownAs.size(), knownBs.size());
		int mushroomsInQuery = min(querySize, n - pos);

		vector<int> query;

		bool isA = knownAs.size() >= knownBs.size();

		for (int i = 0; i < mushroomsInQuery; i++) {
			if (isA) {
				query.push_back(knownAs[i]);
			} else {
				query.push_back(knownBs[i]);
			}

			query.push_back(perm[pos++]);
		}

		int qres = use_machine(query);
		int numChanges = qres / 2 + (qres % 2);
		
		if (isA) {
			res += mushroomsInQuery - numChanges;
			if (qres % 2 == 0) knownAs.push_back(perm[pos-1]);
			else knownBs.push_back(perm[pos-1]);
		} else {
			res += numChanges;
			if (qres % 2 == 0) knownBs.push_back(perm[pos-1]);
			else knownAs.push_back(perm[pos-1]);
		}
	}

	return res;
}

/*
B_B_B_B_B_
*/

• Subtask 1: 80.7143 / 100