Submission #375766

#	Time	Username	Problem	Language	Result	Execution time	Memory
375766		ijxjdjd	Chessboard (IZhO18_chessboard)	C++14	70 / 100	748 ms	262148 KiB

chessboard

#include <bits/stdc++.h>
#define FR(i, N) for (int i = 0; i < int(N); i++)
#define all(x) begin(x), end(x)

#define f first
#define s second

#define int ll
using namespace std;

using ll = long long;


ll calc(pair<pair<int, int>, pair<int, int>> rec, int d, int par) {
    auto p = rec;
    if (p.f.f > p.s.f || p.f.s > p.s.s) {
        return 0;
    }
    int x1 = p.f.f/d;
    int x2 = p.s.f/d;
    int y1 = p.f.s/d;
    int y2 = p.s.s/d;
    if (p.f.f%d == 0 && p.f.s%d == 0 && p.s.f%d == d-1 && p.s.s%d == d-1) {
        int tot = (x2 - x1 + 1) * (y2 - y1 + 1);
        if ((x1 + y1)%2 == par) {
            //top left here is white
            return (((x2 - x1 + 1)*(y2 - y1 + 1) + 1)/2)*d*d;
        }
        else {
            return (tot - ((x2 - x1 + 1)*(y2 - y1 + 1) + 1)/2)*d*d;
        }
    }
    else if (p.f.f%d == 0 && p.s.f%d == d-1 && y1 == y2) {
        int tot = (x2 - x1 + 1);
        if ((x1 + y1)%2 == par) {
            return (tot + 1)/2 * (p.s.s - p.f.s + 1) * d;
        }
        else {
            return (tot - (tot + 1)/2) * (p.s.s - p.f.s + 1) * d;
        }
    }
    else if (p.f.s%d == 0 && p.s.s%d == d-1 && x1 == x2) {
        int tot = (y2 - y1 + 1);
        if ((x1 + y1)%2 == par) {
            return (tot + 1)/2 * (p.s.f - p.f.f + 1)*d;
        }
        else {
            return (tot - (tot + 1)/2) * (p.s.f - p.f.f + 1)*d;
        }
    }
    else if (x1 == x2 && y1 == y2) {
        if ((x1 + y1)%2 == par) {
           return (p.s.f - p.f.f + 1) * (p.s.s - p.f.s + 1);
        }
        else {
            return 0;
        }
    }
    else if (x1 == x2) {
        auto left = rec;
        left.s.s = y1*d+d-1;
        auto right = rec;
        right.f.s = y2*d;
        rec.f.s = (y1+1)*d;
        rec.s.s = y2*d-1;
        return calc(left, d, par) + calc(right, d, par) + calc(rec, d, par);
    }
    else if (y1 == y2) {
        auto top = rec;
        top.s.f = x1*d + d - 1;
        auto bot = rec;
        bot.f.f = x2*d;
        rec.f.f = top.s.f+1;
        rec.s.f = bot.f.f-1;
        return calc(top, d, par) + calc(bot, d, par) + calc(rec, d, par);
    }
    else {
        auto tleft = rec;
        auto bleft = rec;
        auto tright = rec;
        auto bright = rec;

        tleft.s.s = y1*d + d-1;
        tleft.s.f = x1*d + d-1;

        bleft.f.f = x2*d;
        bleft.s.s = y1*d + d-1;

        tright.f.s = y2*d;
        tright.s.f = x1*d + d-1;

        bright.f.f = x2*d;
        bright.f.s = y2*d;


        auto left = rec;
        auto right = rec;
        auto bot = rec;
        auto top = rec;

        left.f.f = tleft.s.f+1;
        left.f.s = bleft.f.s-1;
        tleft.s.s= y1*d + d-1;

        right.f.f = tright.s.f+1;
        right.s.f = bright.f.s-1;
        right.f.s=y2*d;

        bot.f.s = bleft.s.s+1;
        bot.s.s=bright.f.s-1;
        bot.f.f=x2*d;

        top.f.s=tleft.s.s+1;
        top.s.s=tright.f.s-1;
        top.s.f=x1*d+d-1;

        rec.f.f = d*(x1 + 1);
        rec.f.s = d*(y1 + 1);
        rec.s.f = d*x2-1;
        rec.s.s = d*y2-1;

        return calc(tleft, d, par) + calc(bleft, d, par) + calc(tright, d, par) + calc(bright, d, par) + calc(left, d, par) + calc(right, d, par) + calc(bot, d, par) + calc(top, d, par) + calc(rec, d, par);
    }

}
signed main() {
	cin.tie(0);
	cin.sync_with_stdio(0);
	int N, K;
	cin >> N >> K;
	vector<pair<pair<int, int>, pair<int, int>>> vec(K);
	for (int i = 0; i < K; i++) {
        cin >> vec[i].f.f >> vec[i].f.s >> vec[i].s.f >> vec[i].s.s;
        vec[i].f.f--;
        vec[i].f.s--;
        vec[i].s.f--;
        vec[i].s.s--;
	}
	int ans = N*N;
	for (int d = 1; d < N; d++) {
        if (N%d == 0) {
            int cnt = N/d;
//            ll white;
//            ll black;

            int black = d*d*((cnt * cnt)+1)/2;
            int white = d*d*(cnt*cnt - ((cnt*cnt)+1)/2);
            for (auto& p : vec) {
                int tot = (p.s.f - p.f.f + 1) * (p.s.s - p.f.s + 1);

                int res1 = calc(p, d, 0);
                int res2 = calc(p, d, 1);

                black += res2;
                black -= tot-res2;

                white += res1;
                white -= tot-res1;
            }
            ans = min({ans, white, black});
            //top left is black
        }
	}
	cout << ans << '\n';
}

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