Submission #335330

#	Time	Username	Problem	Language	Result	Execution time	Memory
335330		limabeans	Chessboard (IZhO18_chessboard)	C++17	70 / 100	277 ms	4460 KiB

chessboard

#include <bits/stdc++.h>
using namespace std;

template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl





using ll = long long;

const ll inf = 1e18;



ll n,k;
vector<pair<ll,ll>> a;



ll solve(ll x) {
    map<ll,ll> dp;
    for (auto p: a) {
	dp[(p.first/x + p.second/x)%2]++;
    }
    ll res = inf;
    ll cells = (n/x)*(n/x);
    ll area = x*x;
    //even black
    {
	ll sq = (cells/2 + (n/x)%2);
	ll cur = (sq*area - dp[0]) + dp[1];
	res = min(res, cur);
    }
    //odd black
    {
	ll sq = cells/2;
	ll cur = (sq*area - dp[1]) + dp[0];
	res = min(res, cur);
    }
    return res;
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);  cout.tie(0);

    cin>>n>>k;
    a.resize(k);
    for (int i=0; i<k; i++) {
	cin>>a[i].first>>a[i].second;
	cin>>a[i].first>>a[i].second;
	--a[i].first; --a[i].second;
    }

    ll res = inf;

    for (ll i=1; i<n; i++) {
	if (n%i==0) {
	    ll cur=solve(i);
	    //cout<<i<<": "<<cur<<endl;
	    res = min(res, cur);
	}
    }

    cout<<res<<endl;     
    return 0;
}

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