Submission #898279

#	Time	Username	Problem	Language	Result	Execution time	Memory
898279		marcid	Chessboard (IZhO18_chessboard)	C++17	100 / 100	153 ms	8404 KiB

chessboard

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