Submission #289676

#	Time	Username	Problem	Language	Result	Execution time	Memory
289676		luciocf	Chessboard (IZhO18_chessboard)	C++14	100 / 100	709 ms	4348 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;

pair<pii, pii> rect[maxn];

ll qtd(int k, int d)
{
	if (k < 0) return 0;
	++k;
	int oldk = k;

	ll ans = (k/(2*d))*d;
	k -= ((k/(2*d))*(2*d));

	return (ans+min(d, k));
}

ll get_menor(int i, int d)
{
	ll linha = qtd(rect[i].ss.ss, d)-qtd(rect[i].ff.ss-1, d);
	ll col = qtd(rect[i].ss.ff, d)-qtd(rect[i].ff.ff-1, d);

	return linha*col;
}

ll get_maior(int i, int d)
{
	ll linha = (rect[i].ss.ss-rect[i].ff.ss+1) - (qtd(rect[i].ss.ss, d)-qtd(rect[i].ff.ss-1, d));
	ll col = (rect[i].ss.ff-rect[i].ff.ff+1) - (qtd(rect[i].ss.ff, d)-qtd(rect[i].ff.ff-1, d));

	return linha*col;
}

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

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

		rect[i].ff.ff--, rect[i].ff.ss--;
		rect[i].ss.ff--, rect[i].ss.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;

		ll p = 0, b = 0;

		for (int i = 1; i <= k; i++)
		{
			ll x = get_menor(i, d) + get_maior(i, d);

			p += x;

			b += (1ll*(rect[i].ss.ff-rect[i].ff.ff+1)*(rect[i].ss.ss-rect[i].ff.ss+1) - x);
		}

		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 'll qtd(int, int)':
chessboard.cpp:20:6: warning: unused variable 'oldk' [-Wunused-variable]
   20 |  int oldk = k;
      |      ^~~~
chessboard.cpp: In function 'int main()':
chessboard.cpp:47:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   47 |  scanf("%d %d", &n, &k);
      |  ~~~~~^~~~~~~~~~~~~~~~~
chessboard.cpp:51:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   51 |   scanf("%d %d", &rect[i].ff.ff, &rect[i].ff.ss);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
chessboard.cpp:52:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   52 |   scanf("%d %d", &rect[i].ss.ff, &rect[i].ss.ss);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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