Submission #961333

#	Time	Username	Problem	Language	Result	Execution time	Memory
961333		mgch	Chessboard (IZhO18_chessboard)	C++14	8 / 100	19 ms	2920 KiB

chessboard

#include <bits/stdc++.h>

using namespace std;

const int N = 4107, L = 26, K = 66, MOD = 1000000007;

int main() {
//  freopen("input.txt", "r", stdin);
//    ios::sync_with_stdio(false); cin.tie(0);
    int n, k;
    scanf("%d%d", &n, &k);
    vector < pair <int, int> > l(k), r(k);
    long long sq = 0;
    for (int i = 0; i < k; ++i) {
        scanf("%d%d%d%d", &l[i].first, &l[i].second, &r[i].first, &r[i].second);
        sq += 1LL * (r[i].first - l[i].first + 1) * (r[i].second - l[i].second + 1);
    }
    auto ways = [&](int l, int r, int d, int s) {
        //return ((r - 1) / (2 * d) + max((r - 1) % (2 * d) - d, 0)) - (l > 1 ? (l - 2) / (2 * d) + max((l - 2) % (2 * d) - d, 0));
        int cnt = 0;
        for (int i = l; i <= r; ++i) {
            cnt += (i - 1) / d % 2 == s;
        }
        return cnt;
    };
    auto calc = [&](int d, int s) {
        long long ret = 0;
        for (int i = 0; i < k; ++i) {
            //lx[i] <= x <= rx[i] and ly[i] <= y <= ry[i] and (x-1)/d % 2 == 0 and (y-1)/d % 2 == 0
            ret += 1LL * ways(l[i].first, r[i].first, d, s) * ways(l[i].second, r[i].second, d, s);
        }
        return (sq - ret) + 1LL * (1LL * (n / d) * (n / d) + 1 - s) / 2 * (1LL * d * d) - ret;
        //  min  + 1LL * n * n - 1LL * (1LL * (n / d) * (n / d) + 1 - s) / 2 - (sq - ret) + ret;
    };
    long long ans = LLONG_MAX / 2;
    for (int d = 1; d * d <= n; ++d) {
        if (n % d == 0) {
            ans = min(ans, calc(d, 0));
            ans = min(ans, calc(d, 1));
            if (d * d != n && d != 1) ans = min(ans, calc(n / d, 0));
            if (d * d != n && d != 1) ans = min(ans, calc(n / d, 1));
        }
    }
    cout << ans << '\n';
	return 0;
}

Compilation message (stderr)

chessboard.cpp: In function 'int main()':
chessboard.cpp:11:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |     scanf("%d%d", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~
chessboard.cpp:15:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |         scanf("%d%d%d%d", &l[i].first, &l[i].second, &r[i].first, &r[i].second);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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