Submission #378601

#	Time	Username	Problem	Language	Result	Execution time	Memory
378601		8e7	Chessboard (IZhO18_chessboard)	C++14	100 / 100	810 ms	4708 KiB

chessboard

//Challenge: Accepted
#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>
#define ll long long
#define maxn 100005
#define pii pair<int, int>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);cin.tie(0);
using namespace std;
struct rect{
	ll x1, y1, x2, y2;
	rect() {
		x1 = 0, y1 = 0, x2 = 0, y2 = 0;
	}
	rect(int a, int b, int c, int d) {
		x1 = a, y1 = b, x2 = c, y2 = d;
	}
};
vector<rect> v;

inline ll wnum(ll x, ll y, ll len) {
	if (x < 0 || y < 0) return 0;
	ll ret = 0;
	ll cx = x / len, cy = y / len;
	ll lx = x % len, ly = y % len;
	if (cx % 2 == 0 || cy % 2 == 0) {
		ret += len * len * (cx * cy / 2);
	} else {
		ret += len * len * ((cx * cy + 1) / 2);
	}

	if (cy % 2 == 0) { //white
		ret += ly * ((cx + 1) / 2) * len;
	} else {
		ret += ly * (cx / 2) * len;
	}
	if (cx % 2 == 0) {
		ret += lx * ((cy + 1) / 2) * len;
	} else {
		ret += lx * (cy / 2) * len;
	}
	if (((cx + cy) % 2) == 0) ret += lx * ly;
	//cout << x << " " << y << " " << len << " " << ret << endl;
	return ret;
}
ll solve(ll n, ll len) {
	ll val = n * n - wnum(n, n, len);
	//cout << len << endl;
	for (rect a:v) {
		ll wn = wnum(a.x2+1, a.y2+1, len) - wnum(a.x1, a.y2+1, len) - wnum(a.x2+1, a.y1, len) + wnum(a.x1, a.y1, len);
		//cout << a.x1 << " " << a.y1 << " " << wn << endl;
		val += 2 * wn - (a.x2 - a.x1 + 1) * (a.y2 - a.y1 + 1);
	}
	val = min(val, n * n - val);
	//cout << len << " " << val << endl;
	return val;
}
int main() {
	io
	ll n, k;
	cin >> n >> k;
	for (int i = 0;i < k;i++) {
		ll x1, y1, x2, y2;
		cin >> x1 >> y1 >> x2 >> y2;
		x1--, y1--, x2--, y2--;
		v.push_back(rect(x1, y1, x2, y2));
	}
	ll ans = 1LL<<60;
	for (ll i = 1;i * i <= n;i++) {
		if (n % i == 0) {
			ans = min(ans, solve(n, i));
			if (i * i != n && i != 1) {
				ans = min(ans, solve(n, n / i));
			}
		}
	}
	cout << ans << endl;
}
/*
2 0

6 8
3 3 3 3
1 2 1 2
3 4 3 4
5 5 5 5
4 3 4 3
4 4 4 4
2 1 2 1
3 6 3 6

4 1
4 1 4 4
 */

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