Submission #824259

#	Time	Username	Problem	Language	Result	Execution time	Memory
824259		thimote75	Counting Mushrooms (IOI20_mushrooms)	C++14	79.86 / 100	7 ms	316 KiB

mushrooms

#include "mushrooms.h"

#include <bits/stdc++.h>

using namespace std;

using idata = vector<int>;

const int QK = 273;

int count_mushrooms(int n) {
	idata Av = { 0 };
	idata Bv = { };

	if (n < QK) {
		for (int i = 1; i < n; i ++) {
			int res = use_machine({ 0, i });
			if (res) Bv.push_back(i);
			else Av.push_back(i);
		}

		return Av.size();
	}

	if (use_machine({ 0, 1 }) == 0) Av.push_back(1);
	else Bv.push_back(1);

	if (use_machine({ 0, 2 }) == 0) Av.push_back(2);
	else Bv.push_back(2);
	
	if (Av.size() >= 2) {
		for (int i = 3; i < QK; i += 2) {
			int res = use_machine({ i, 0, i + 1, Av[1] });

			if (res & 1) Bv.push_back(i);
			else Av.push_back(i);

			if (res & 2) Bv.push_back(i + 1);
			else Av.push_back(i + 1);
		}
	} else {
		for (int i = 3; i < QK; i += 2) {
			int res = use_machine({ i, Bv[0], i + 1, Bv[1] });

			if (res & 1) Av.push_back(i);
			else Bv.push_back(i);

			if (res & 2) Av.push_back(i + 1);
			else Bv.push_back(i + 1);
		}
	}

	int offset     = 0;
	int multiplier = 1;
	
	if (Bv.size() > Av.size()) {
		Bv.swap(Av);
		offset = n;
		multiplier = -1;
	}

	int total = Av.size();

	for (int i = QK; i < n; i += Av.size() - 1) {
		idata templ;

		int cnt = 0;
		for (int j = 0; j < Av.size() - 1; j ++) {
			templ.push_back(Av[j]);

			if (i + j >= n) continue ;

			cnt ++;
			templ.push_back(i + j);
		}
		templ.push_back(Av[Av.size() - 1]);

		int res = use_machine(templ);

		int c0 = (cnt) - (res >> 1);
		total += c0;
	}

	return offset + multiplier * total;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:68:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   68 |   for (int j = 0; j < Av.size() - 1; j ++) {
      |                   ~~^~~~~~~~~~~~~~~

• Subtask 1: 79.8587 / 100