Ruudukko

#include <cstdint>
#include <string>
#include <iostream>
#include <vector>
#include <bitset>

int main()
{
	int n, m;
	std::cin >> n >> m;
	std::cin.ignore();

	std::bitset<2000 * 2000> bits;
	int y1, x1, y2, x2;
	for (int i = 0; i < m; ++i)
	{
		std::cin >> y1 >> x1 >> y2 >> x2;
		y1--; x1--; y2--; x2--;

		for (int y = y1; y <= y2; ++y)
		{
			int index1 = y * n + x1;
			int index2 = y * n + x2 + 1;
			bits.flip(index1);
			bits.flip(index2);
		}
	}

	std::string printtaus;
	char merkki = '.';
	for (int i = 0; i < n * n; ++i)
	{
		if (bits.test(i) == 1)
			merkki = merkki == '.' ? '#' : '.';
		printtaus += merkki;
	}

	for (int i = 1; i < n; ++i)
		printtaus.insert(i * n + i - 1, 1, '\n');

	std::cout << printtaus << std::endl;
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 2, 3

Verdict: ACCEPTED

Test 3

Group: 2, 3

Verdict: ACCEPTED

Test 4

Group: 3

Verdict: RUNTIME ERROR

terminate called after throwing an instance of 'std::out_of_range'
  what():  bitset::flip: __position (which is 4000000) >= _Nb (which is 4000000)

Test 5

Group: 3

Verdict: TIME LIMIT EXCEEDED