Submission #992509

#	Time	Username	Problem	Language	Result	Execution time	Memory
992509		tch1cherin	Chessboard (IZhO18_chessboard)	C++17	8 / 100	24 ms	5724 KiB

chessboard

#include <bits/stdc++.h>
using namespace std;
 
int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int N, K;
  cin >> N >> K;
  vector<vector<array<int, 3>>> rect(N + 1);
  for (int i = 0; i < K; i++) {
    int x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    x1--, y1--, y2--;
    rect[x1].push_back({y1, y2, 1});
    rect[x2].push_back({y1, y2, -1});
  }
  auto Even = [&](int L, int R, int d) {
    int l = L % (2 * d) >= d ? L + d - L % d : L;
    int r = R % (2 * d) >= d ? R - R % d - 1 : R;
    return l > r ? pair {0, -1} : pair {l / (2 * d) * d + l % (2 * d), r / (2 * d) * d + r % (2 * d)};
  };
  auto Odd = [&](int L, int R, int d) {
    int l = L % (2 * d) < d ? L + d - L % d : L;
    int r = R % (2 * d) < d ? R - R % d - 1 : R;
    return l > r ? pair {0, -1} : pair {l / (2 * d) * d + (l - d) % (2 * d), r / (2 * d) * d + (r - d) % (2 * d)};
  };
  long long answer = numeric_limits<long long>::max();
  for (int d = 1; d < N; d++) {
    if (N % d == 0) {
      int N_even = N / (2 * d) * d + min(d, N % (2 * d)), N_odd = N / (2 * d) * d + max(0, N % (2 * d) - d);
      int cnt_e = 0, cnt_o = 0;
      long long answer_e = 0, answer_o = 0;
      for (int i = 0; i < N; i++) {
        for (auto [j1, j2, t] : rect[i]) {
          auto [j1_e, j2_e] = Even(j1, j2, d);
          auto [j1_o, j2_o] = Odd(j1, j2, d);
          cnt_e += j2_e - j1_e + 1;
          cnt_o += j2_o - j1_o + 1;
        }
        int r = (i / d) % 2;
        answer_o += (r ? cnt_e : N_even - cnt_e) + (!r ? cnt_o : N_odd - cnt_o);
        answer_e += (!r ? cnt_e : N_even - cnt_e) + (r ? cnt_o : N_odd - cnt_o);
      }
      answer = min({answer, answer_e, answer_o});
    }
  }
  cout << answer << "\n";
}

• Subtask 1: 8 / 8
• Subtask 2: 0 / 8
• Subtask 3: 0 / 15
• Subtask 4: 0 / 16
• Subtask 5: 0 / 23
• Subtask 6: 0 / 30