Submission #685309

#	Time	Username	Problem	Language	Result	Execution time	Memory
685309		dostigator	Chessboard (IZhO18_chessboard)	C++17	39 / 100	39 ms	9680 KiB

chessboard

#include <bits/stdc++.h>

using namespace std;

#define all(a) a.begin(),a.end()
#define pb push_back
#define vt vector
#define endl '\n'
#define Y second
#define X first
typedef long long ll;
typedef long double ld;
const ll mod=1e9+7;
const ll INF=1e18;
const int inf=1e9;
const int N=2e5+505;
const int M=3e3+10;
const int dx[]={0,0,1,-1};
const int dy[]={1,-1,0,0};

/*From Benq:
    stuff you should look for
        * int overflow, array bounds
        * special cases (n=1?)
        * do smth instead of nothing and stay organized
        * WRITE STUFF DOWN
        * DON'T GET STUCK ON ONE APPROACH*/

int n,k,used[3000][3000];

void solve(){
	cin>>n>>k;
	for(int i=1; i<=k; ++i){
		int x1,y1,x2,y2;
		cin>>x1>>y1>>x2>>y2;
		used[x1][y1]++;
	}vt<int>lst;
	for(int i=1; i<=n; ++i)for(int j=1; j<=n; ++j)used[i][j]+=used[i][j-1]+used[i-1][j]-used[i-1][j-1];
	for(int d=1; d*d<=n; ++d){
		if(n%d==0){
			lst.pb(d);
			if(n/d!=d)lst.pb(n/d);
		}
	}int ans=inf;
	for(int del:lst){
		int cnt=0;
		int ok=0;
		int yes=0;
		//cout<<del<<endl;
		for(int i=1; i<=n; i+=del){
			++ok;
			int ok2=0;
			for(int j=1; j<=n; j+=del){
				++ok2;
				if((ok+ok2)%2==0){
					cnt+=(used[i+del-1][j+del-1]-used[i+del-1][j-1]-used[i-1][j+del-1]+used[i-1][j-1]);
					continue;
				}
				//cout<<del<<' '<<i<<' '<<j<<' '<<(used[i+del-1][j+del-1]-used[i+del-1][j-1]-used[i-1][j+del-1]+used[i-1][j-1])<<endl;
				yes=1;
				cnt+=(del*del)-(used[i+del-1][j+del-1]-used[i+del-1][j-1]-used[i-1][j+del-1]+used[i-1][j-1]);
			}
		}int cnt2=0;
		//cout<<endl
		ok=0;
		for(int i=1; i<=n; i+=del){
			++ok;
			int ok2=0;
			for(int j=1; j<=n; j+=del){
				++ok2;
				if((ok+ok2)%2){
					cnt2+=(used[i+del-1][j+del-1]-used[i+del-1][j-1]-used[i-1][j+del-1]+used[i-1][j-1]);
					continue;
				}
		//		cout<<i<<' '<<j<<endl;
				cnt2+=(del*del)-(used[i+del-1][j+del-1]-used[i+del-1][j-1]-used[i-1][j+del-1]+used[i-1][j-1]);
			}
		}//cout<<cnt<<' '<<cnt2<<endl;
		ans=min({ans,cnt2});
		if(yes)ans=min(ans,cnt);
	}cout<<ans<<endl;
}

int main(){
	//srand(time(0));
	//freopen("hotel.in","r",stdin);
	//freopen("hotel.out","w",stdout);
	ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	int tt=1,lolol=0;
//	cin>>tt;
	while(tt--) {
		//cout<<"Case "<<++lolol<<": ";
		solve();
	}
}

Compilation message (stderr)

chessboard.cpp: In function 'int main()':
chessboard.cpp:89:11: warning: unused variable 'lolol' [-Wunused-variable]
   89 |  int tt=1,lolol=0;
      |           ^~~~~

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