Submission #750009

#	Time	Username	Problem	Language	Result	Execution time	Memory
750009		Pring	The Kingdom of JOIOI (JOI17_joioi)	C++14	100 / 100	1306 ms	102572 KiB

joioi

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

#define int long long
typedef pair<int, int> pii;

const int MXN = 2005;
int n, m, a[MXN][MXN], b[MXN][MXN];
bitset<MXN> lu[MXN];
pii C[MXN];
int big = 0, small = LLONG_MAX;
int l, r;

bool LU1() {
    for (int i = 0; i < n; i++) {
        lu[i].reset();
        for (int j = 0; j < m; j++) {
            // if (i) lu[i][j] |= lu[i - 1][j];
            // if (j) lu[i][j] |= lu[i][j - 1];
            if (i && lu[i - 1][j]) lu[i][j] = true;
            if (j && lu[i][j - 1]) lu[i][j] = true;
            if (b[i][j] == 2) lu[i][j] = true;
            if (b[i][j] == 1 && lu[i][j]) return false;
        }
    }
    // for (int i = 0; i < n; i++) {
    //     for (int j = 0; j < m; j++) cout << (lu[i][j] ? '1' : '0');
    //     cout << endl;
    // }
    // for (int i = 0; i < n; i++) {
    //     for (int j = 0; j < m; j++) {
    //         if (b[i][j] == 1 && lu[i][j]) return false;
    //     }
    // }
    return true;
}

bool LU2() {
    for (int i = 0; i < n; i++) {
        lu[i].reset();
        for (int j = 0; j < m; j++) {
            // if (i) lu[i][j] |= lu[i - 1][j];
            // if (j) lu[i][j] |= lu[i][j - 1];
            if (i && lu[i - 1][j]) lu[i][j] = true;
            if (j && lu[i][j - 1]) lu[i][j] = true;
            if (b[i][j] == 1) lu[i][j] = true;
            if (b[i][j] == 2 && lu[i][j]) return false;
        }
    }
    return true;
}

bool CHECK() {
    // for (int i = 0; i < n; i++) {
    //     for (int j = 0; j < m; j++) {
    //         cout << b[i][j] << ' ';
    //     }
    //     cout << endl;
    // }
    if (LU1()) return true;
    if (LU2()) return true;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m / 2; j++) {
            swap(b[i][j], b[i][m - j - 1]);
        }
    }
    if (LU1()) return true;
    if (LU2()) return true;
    return false;
}

bool check(int x) {
    if (big - 2 * x < 1) { // cross
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (a[i][j] < big - x) b[i][j] = 1;
                else if (x < a[i][j]) b[i][j] = 2;
                else b[i][j] = 0;
            }
        }
    } else { // not cross
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (a[i][j] <= x) b[i][j] = 1;
                else if (big - x <= a[i][j]) b[i][j] = 2;
                else return false;
            }
        }
    }
    // cout << x << endl;
    bool f = CHECK();
    // cout << (f ? "YES" : "NO") << endl;
    return f;
}

int32_t main() {
    cin.tie(0) -> sync_with_stdio(false);
    cin >> n >> m;
    for (int i = 0; i < n; i++) for (int j = 0; j < m; j++) {
        cin >> a[i][j];
        big = max(big, a[i][j]);
        small = min(small, a[i][j]);
    }
    for (int i = 0; i < n; i++) for (int j = 0; j < m; j++) {
        a[i][j] -= small;
    }
    big -= small;
    int l = -1, r = big;
    while (l + 1 < r) {
        int mid = (l + r) >> 1;
        (check(mid) ? r : l) = mid;
    }
    cout << r << endl;
    // for (int i = 0; i < 4; i++) {
    //     for (int j = 0; j < 4; j++) {
    //         cin >> b[i][j];
    //     }
    // }
    // n = 4, m = 4;
    // cout << LU1() << endl;
    return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 45 / 45
• Subtask 3: 40 / 40