Submission #167788

#	Time	Username	Problem	Language	Result	Execution time	Memory
167788		abil	Chessboard (IZhO18_chessboard)	C++14	16 / 100	46 ms	3652 KiB

chessboard

#include <bits/stdc++.h>

#define fr first
#define sc second
#define pb push_back
#define mk make_pair
#define all(s) s.begin(),s.end()
#define int long long

using namespace std;

const int N = (1e5 + 12);
const int mod = (1e9 + 7);
const int INF = (0x3f3f3f3f);

int ans = 1e16;
int n, k, x[2][N], y[2][N];

void calc(int div){
	int bl = n / div, cnt = 0, x1, y1, cnt1 = 0;
	if(bl & 1){
		cnt += div * div * ((bl + 1) / 2) * ((bl + 1) / 2);
		cnt += div * div * (bl / 2) * (bl / 2);
		cnt1 += n * n - cnt;
		for(int i = 1;i <= k; i++){
			x1 = x[0][i];
			y1 = y[0][i];
			x1 = (x1 + bl - 1) / bl;
			y1 = (y1 + bl - 1) / bl;
			if((x1 + y1) % 2 == 1){
				cnt++;
				cnt1--;
			}
			else{
				cnt--;
				cnt1++;
			}
		}
		ans = min(ans, cnt);
		ans = min(ans, cnt1);
	}
	else{
		cnt += div * div * (bl / 2) * bl;
		cnt1 += n * n - cnt;
		for(int i = 1;i <= k; i++){
			x1 = x[0][i];
			y1 = y[0][i];
			x1 = (x1 + bl - 1) / bl;
			y1 = (y1 + bl - 1) / bl;
			if((x1 + y1) % 2 == 1){
				cnt++;
				cnt1--;
			}
			else{
				cnt--;
				cnt1++;
			}
		}
		ans = min(ans, cnt);
		ans = min(ans, cnt1);
	}
}
main()
{
	cin >> n >> k;
	for(int i = 1;i <= k; i++){
		scanf("%lld%lld%lld%lld", &x[0][i], &y[0][i], &x[1][i], &y[1][i]);
	}
	if(n % 2 == 1){
		int x1, y1;
		int cnt = n * n / 2ll + 1ll, cnt1 = n * n / 2ll;
		for(int i = 1;i <= k; i++){
			x1 = x[0][i];
			y1 = y[0][i];
			if((x1 + y1) % 2 == 0){
				cnt--;
				cnt1++;
			}
			else{
				cnt++;
				cnt1--;
			}
		}
		ans = min(ans, cnt);
		ans = min(ans, cnt1);
	}
	else{
		int x1, y1;
		int cnt = n * n / 2ll, cnt1 = n * n / 2ll;
		for(int i = 1;i <= k; i++){
			x1 = x[0][i];
			y1 = y[0][i];
			if((x1 + y1) % 2 == 0){
				cnt--;
				cnt1++;
			}
			else{
				cnt++;
				cnt1--;
			}
		}
		ans = min(ans, cnt);
		ans = min(ans, cnt1);
	}
	for(int i = 2;i * i <= n; i++){
		if(n % i == 0){
			calc(i);
			calc(n / i);
		}
	}
	cout << ans;
}

Compilation message (stderr)

chessboard.cpp:63:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main()
      ^
chessboard.cpp: In function 'int main()':
chessboard.cpp:67:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld%lld%lld%lld", &x[0][i], &y[0][i], &x[1][i], &y[1][i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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