Submission #883690

#	Time	Username	Problem	Language	Result	Execution time	Memory
883690		Sokol080808	Chessboard (IZhO18_chessboard)	C++17	100 / 100	145 ms	8404 KiB

chessboard

#ifdef ONPC
    #define _GLIBCXX_DEBUG
#endif

#include <bits/stdc++.h>
#include <malloc.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#pragma GCC optimize("O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
#pragma GCC optimize("unroll-loops")

using namespace __gnu_pbds;
using namespace std;

#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()

using ll = long long;
using ull = unsigned long long;
using ld = long double;

template<typename T1, typename T2> istream& operator>>(istream& in, pair<T1, T2>& p) {in >> p.first >> p.second; return in;}
template<typename T1, typename T2> ostream& operator<<(ostream& out, pair<T1, T2>& p) {out << p.first << ' ' << p.second; return out;}
template<typename T> istream& operator>>(istream& in, vector<T>& v) {for (auto& x : v) in >> x; return in;}
template<typename T> ostream& operator<<(ostream& out, vector<T>& v) {for (auto& x : v) out << x << ' '; return out;}
template<typename T> ostream& operator<<(ostream& out, set<T>& v) {for (auto& x : v) out << x << ' '; return out;}
template<typename T> ostream& operator<<(ostream& out, multiset<T>& v) {for (auto& x : v) out << x << ' '; return out;}

const int MAX_INT = 2147483647;
const double pi = acos(-1.0);
const int mod = 1e9 + 7;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

struct rect {
    ll x1, y1, x2, y2;
};

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    vector<rect> a;
    ll n, k;
    cin >> n >> k;
    for (int i = 0; i < k; i++) {
        int x1, y1, x2, y2;
        cin >> x1 >> y1 >> x2 >> y2;
        a.push_back({x1, y1, x2, y2});
    }

    ll res = n * n;
    ll wh_cnt[n + 1], bl_cnt[n + 1];
    for (int d = 1; d < n; d++) {
        if (n % d) continue;

        wh_cnt[0] = 0;
        bl_cnt[0] = 0;
        for (int i = 1; i <= n; i++) {
            int id = (i + d - 1) / d;
            wh_cnt[i] = wh_cnt[i - 1];
            bl_cnt[i] = bl_cnt[i - 1];
            if (id % 2) {
                wh_cnt[i]++;
            } else {
                bl_cnt[i]++;
            }
        }
        
        ll cur = (n / d) * (n / d) / 2 * d * d;
        for (auto [x1, y1, x2, y2] : a) {
            cur += (wh_cnt[x2] - wh_cnt[x1 - 1]) * (wh_cnt[y2] - wh_cnt[y1 - 1]) + (bl_cnt[x2] - bl_cnt[x1 - 1]) * (bl_cnt[y2] - bl_cnt[y1 - 1]);
            cur -= (wh_cnt[x2] - wh_cnt[x1 - 1]) * (bl_cnt[y2] - bl_cnt[y1 - 1]) + (bl_cnt[x2] - bl_cnt[x1 - 1]) * (wh_cnt[y2] - wh_cnt[y1 - 1]);
        }
        res = min({res, cur, n * n - cur});
    }

    cout << res << '\n';

    return 0;
}

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