Submission #289653

#	Time	Username	Problem	Language	Result	Execution time	Memory
289653		luciocf	Chessboard (IZhO18_chessboard)	C++14	70 / 100	272 ms	1144 KiB

chessboard

#include <bits/stdc++.h>

#define ff first
#define ss second

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;

const int maxn = 1e5+10;
const ll inf = 1e18+10;

pii pt[maxn];

int main(void)
{
	int n, k;
	scanf("%d %d", &n, &k);

	for (int i = 1; i <= k; i++)
	{
		scanf("%d %d", &pt[i].ff, &pt[i].ss);
		scanf("%d %d", &pt[i].ff, &pt[i].ss);

		pt[i].ff--, pt[i].ss--;
	}

	vector<int> D;

	for (int d = 1; d*d <= n; d++)
	{
		if (n%d) continue;

		D.push_back(d);
		if (n/d != d) D.push_back(n/d);
	}

	ll ans = inf;

	for (auto d: D)
	{
		if (d == n) continue;

		int p = 0, b = 0;

		for (int i = 1; i <= k; i++)
		{
			int ma = pt[i].ff%(2*d);
			int mb = pt[i].ss%(2*d);

			if ((ma < d && mb < d) || (ma >= d && mb >= d)) p++;
			else b++;
		}

		ll x = ((n+2*d-1)/(2*d));
		ll y = n/(2*d);

		ll tot_p = 1ll*d*d*(x*x+y*y);

		ans = min(ans, (tot_p-p)+b);

		swap(p, b);
		tot_p = 1ll*n*n-tot_p;

		ans = min(ans, (tot_p-p)+b);
	}

	printf("%lld\n", ans);
}

Compilation message (stderr)

chessboard.cpp: In function 'int main()':
chessboard.cpp:19:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   19 |  scanf("%d %d", &n, &k);
      |  ~~~~~^~~~~~~~~~~~~~~~~
chessboard.cpp:23:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   23 |   scanf("%d %d", &pt[i].ff, &pt[i].ss);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
chessboard.cpp:24:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   24 |   scanf("%d %d", &pt[i].ff, &pt[i].ss);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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