Submission #684147

#	Time	Username	Problem	Language	Result	Execution time	Memory
684147		mychecksedad	Chessboard (IZhO18_chessboard)	C++17	47 / 100	322 ms	262144 KiB

chessboard

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define pb push_back
#define all(x) x.begin() x.end()
#define MOD (1e9+7)
const int N = 1e6;

int n, k;
vector<vector<bool>> v;
void solve(){
	cin >> n >> k;
	int a = 0;
	for(int i = 1; i <= sqrt(n); ++i){
		if(n % i == 0) a++;
	}
	if(a == 1){
		int c1 = 0, c2 = 0;
		for(int i = 0; i < k; ++i){
			int x1, x2, y1, y2; cin >> x1 >> y1 >> x2 >> y2;
			int val = x1-1+y1-1;
			if(val%2) c1++;
			else c2++;
		}
		cout << min(c1 + ll(n)*n/2 + 1 - c2, c2 + ll(n)*n/2 - c1);
		return;
	}
	v.resize(n);
	for(int i = 0; i < n; ++i) v[i].resize(n);
	for(int i = 0; i < k; ++i){
		int x1, x2, y1, y2; cin >> x1 >> y1 >> x2 >> y2;
		v[x1 - 1][y1 - 1] = 1;
	}
	int ans = MOD;
	for(int i = 1; i < n; ++i){
		if(n % i == 0){
			for(int rep = 0; rep < 2; ++rep){
				int c = 0;
				for(int jx = 0; jx < n; ++jx){
					for(int jy = 0; jy < n; ++jy){
						int val = jx/i + jy/i;
						c += (val%2)^rep^v[jx][jy];
					}
				}
				ans = min(ans, c);
			}

		}
	}
	cout << ans;
}

int main(){
	solve();
	return 0;
}

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