Ruudukko

#include <bits/stdc++.h>

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(0);
    int n, m;
    std::cin >> n >> m;
    std::vector<std::vector<int64_t>> DP(n + 2, std::vector<int64_t>(n + 2));
    for (auto i = 0; i < m; ++i) {
        int y1, x1, y2, x2;
        std::cin >> y1 >> x1 >> y2 >> x2;
        DP[y1][x1] += 1;
        DP[y1][x2 + 1] -= 1;
        DP[y2 + 1][x1] -= 1;
        DP[y2 + 1][x2 + 1] += 1;
    }
    for (auto y = 1; y <= n; ++y) {
        for (auto x = 1; x <= n; ++x) {
            DP[y][x] += DP[y][x - 1];
        }
    }
    for (auto y = 1; y <= n; ++y) {
        for (auto x = 1; x <= n; ++x) {
            DP[y][x] += DP[y - 1][x];
        }
    }
    const std::vector<char> C{'.', '#'};
    for (auto y = 1; y <= n; ++y) {
        for (auto x = 1; x <= n; ++x) {
            std::cout << C[DP[y][x] & 1];
        }
        std::cout << '\n';
    }
}

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: ACCEPTED

Test 5

Group: 3

Verdict: ACCEPTED