Submission #667814

#	Time	Username	Problem	Language	Result	Execution time	Memory
667814		Kaztaev_Alisher	Chessboard (IZhO18_chessboard)	C++17	47 / 100	171 ms	14428 KiB

chessboard

//#pragma GCC optomize ("Ofast")
//#pragma GCC optomize ("unroll-loops")
//#pragma GCC target ("avx,avx2,fma")

#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define sz size
#define cl clear
#define ins insert
#define ers erase
#define pii pair < int , int >
#define pll pair< long long  , long long >
#define all(x) x.begin() , x.end()
#define ios ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define file(s) if (fopen(s".in", "r")) freopen(s".in", "r", stdin), freopen(s".out", "w", stdout)
#define tostr(x) to_string(x)
#define tonum(s) atoi(s.c_str())
#define seon(x) setprecision(x)
#define bpop(x) __builtin_popcount(x)
#define deb(x) cerr << #x  << " = " << x << endl;
#define int ll

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ldb;
const double PI = 3.14159265;

const ll N = 1e6+5 , M = 2e3+5;
const ll mod = 1e9+7;
const ll inf = 1e9;
const ll INF = 1e18;

using namespace std;

int n;
bool u[N];
int dp[M][M];
ll check(int k){
	int cnt0 = 0 , cnt1 = 0;
	int cnt10 = 0 , cnt11 = 0;
	for(int i = 0; i < n; i++){
		for(int j = 0; j < n; j++){
			if((i/k)%2==(j/k)%2) {
				if(dp[i][j] == 1) cnt1++;
				else cnt0++;
			} else {
				if(dp[i][j] == 1) cnt11++;
				else cnt10++;
			}
		}
	}
	return min(cnt0+cnt11 , cnt10+cnt1);
}
void solve(){
	ll k;
	cin >> n >> k;
	if(u[n] == 0){
		ll cnt = 0 , cnt1 = 0;
		for(int i = 1; i <= k; i++){
			ll x , y , x1 , y1;
			cin >> x >> y >> x1 >> y1;
			if(x % 2 == y % 2) cnt++;
			else cnt1++;
		}
		cout << min((n*n+1)/2-cnt+cnt1 , n*n/2-cnt1+cnt) <<"\n";
		return;
	} else {
		for(int i = 1; i <= k; i++){
			ll x , y , x1 , y1;
			cin >> x >> y >> x1 >> y1;
			x--;
			y--;
			dp[x][y] = 1;
		}
		ll mn = INF;
		for(int i = 1; i <= sqrtl(n); i++){
			if(n % i == 0){
				mn = min(mn , check(i));
				if(i > 1) mn = min(mn , check(n/i));
			}
		}
		cout << mn <<"\n";
	}
}
signed main(){
	ios;
	u[1] = 1;
	for(int i = 2; i <= N-5; i++){
		if(u[i] == 1) continue;
		for(ll j = i*i; j <= N-5; j+=i) u[j] = 1;
	}
	solve();
	return 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
*/

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