Ruudukko

#pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int n, m;
bitset<2002> g[2002];

int main() {
  ios_base::sync_with_stdio(0); cin.tie(0);
  cin>>n>>m;

  for (int qi = 0; qi < m; qi++) {
    int y1, x1, y2, x2;
    cin>>y1>>x1>>y2>>x2;
    y1--; x1--; y2--; x2--;
    for (int jy = y1; jy <= y2; jy++) {
      g[jy].flip(x1);
      g[jy].flip(x2+1);
    }
  }

  for (int y = 0; y < n; y++) {
    int rowsum = 0;
    for (int x = 0; x < n; x++) {
      rowsum ^= g[y][x];
      cout << ((rowsum & 1) ? '#' : '.');
    }
    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: TIME LIMIT EXCEEDED