Submission #1128672

#	Time	Username	Problem	Language	Result	Execution time	Memory
1128672		_callmelucian	Chessboard (IZhO18_chessboard)	C++17	100 / 100	882 ms	3604 KiB

chessboard

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

#define int long long

typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pl;
typedef pair<int,int> pii;
typedef tuple<int,int,int> tpl;

#define all(a) a.begin(), a.end()
#define filter(a) a.erase(unique(all(a)), a.end())

const int mn = 5e5 + 5;
ll xL[mn], yL[mn], xR[mn], yR[mn], cnt[2][2];

ll squared (ll a) { return a * a; }

void compute (vector<ll> &a, int L, int R, int u) {
    int dL = L / u, dR = R / u, mid = dR - dL - 1;
    if (dL == dR)
        return a[dL & 1] += R % u - L % u + 1, void();
    a[dL & 1] += u - L % u, a[dR & 1] += 1 + R % u;
    if (mid & 1) {
        a[dL & 1 ^ 1] += ((mid >> 1) + (mid & 1)) * u;
        a[dL & 1] += (mid >> 1) * u;
    }
    else a[0] += (mid >> 1) * u, a[1] += (mid >> 1) * u;
}

signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);

    int n, k; cin >> n >> k;

    vector<int> wish;
    for (int i = 1; i * i <= n; i++) {
        if (n % i) continue;
        wish.push_back(i);
        if (i != n / i && n / i < n) wish.push_back(n / i);
    }

    for (int i = 0; i < k; i++) {
        cin >> xL[i] >> yL[i] >> xR[i] >> yR[i];
        xL[i]--, yL[i]--, xR[i]--, yR[i]--;
    }

    ll ans = LLONG_MAX;
    for (int u : wish) {
        for (int i = 0; i < 2; i++)
            for (int j = 0; j < 2; j++) cnt[i][j] = 0;
        ll sq = n / u;
        cnt[0][0] = (squared((sq >> 1) + (sq & 1)) + squared(sq >> 1)) * u * u;
        cnt[0][1] = (2LL * (sq >> 1) * ((sq >> 1) + (sq & 1))) * u * u;

        for (int i = 0; i < k; i++) {
            vector<ll> row(2), col(2);
            compute(row, xL[i], xR[i], u), compute(col, yL[i], yR[i], u);

//            if (u == 1)
//                cout << row[0] << " " << row[1] << " "<< col[0] << " " << col[1] << "\n";

            ll type_0 = row[0] * col[0] + row[1] * col[1];
            ll type_1 = row[0] * col[1] + row[1] * col[0];
            cnt[0][0] -= type_0, cnt[1][0] += type_0;
            cnt[0][1] -= type_1, cnt[1][1] += type_1;
        }

//        cout << "size-square " << u << " " << cnt[0][0] << " " << cnt[0][1] << " " << cnt[1][0] << " " << cnt[1][1] << "\n";

        ans = min(ans, cnt[0][0] + cnt[1][1]);
        ans = min(ans, cnt[1][0] + cnt[0][1]);
    }

    cout << ans << "\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