Submission #637184

#	Time	Username	Problem	Language	Result	Execution time	Memory
637184		colossal_pepe	The Kingdom of JOIOI (JOI17_joioi)	C++17	100 / 100	1251 ms	133868 KiB

joioi

#include <iostream>
#include <vector>
using namespace std;

const int INF = 1e9 + 1;

int n, m, mn = INF, mx = -INF;
vector<vector<pair<int, int>>> dp;
vector<vector<int>> a, mxr, mnc;

void rotate() {
    vector<vector<int>> b(m, vector<int>(n));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            b[j][n - 1 - i] = a[i][j];
        }
    }
    a = b;
    swap(n, m);
}

void preprocess() {
    mxr.clear();
    mxr.resize(n, vector<int>(m));
    for (int i = 0; i < n; i++) {
        mxr[i][0] = a[i][0];
        for (int j = 1; j < m; j++) {
            mxr[i][j] = max(mxr[i][j - 1], a[i][j]);
        }
    }
    mnc.clear();
    mnc.resize(n, vector<int>(m));
    for (int j = 0; j < m; j++) {
        mnc[n - 1][j] = a[n - 1][j];
        for (int i = n - 2; i >= 0; i--) {
            mnc[i][j] = min(mnc[i + 1][j], a[i][j]);
        }
    }
}

// int minInCol(int i, int j) {
//     int ret = INF;
//     for (int k = n - 1; k >= i; k--) {
//         ret = min(ret, a[k][j]);
//     }
//     return ret;
// }

// int maxInRow(int i, int j) {
//     int ret = 0;
//     for (int k = 0; k <= j; k++) {
//         ret = max(ret, a[i][k]);
//     }
//     return ret;
// }

pair<int, int> solve(int i, int j) {
    if (i == n) return {-INF, INF};
    if (j == -1) return {-INF, INF};
    if (dp[i][j].first != INF) return dp[i][j];
    pair<int, int> p1 = solve(i + 1, j);
    p1.first = max(p1.first, mxr[i][j]);
    pair<int, int> p2 = solve(i, j - 1);
    p2.second = min(p2.second, mnc[i][j]);
    dp[i][j] = max(p1.first - mn, mx - p1.second) < max(p2.first - mn, mx - p2.second) ? p1 : p2;
    return dp[i][j];
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> m;
    a.resize(n, vector<int>(m));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> a[i][j];
            mn = min(mn, a[i][j]);
            mx = max(mx, a[i][j]);
        }
    }
    int ans = mx - mn;
    for (int _ = 0; _ < 4; _++) {
        dp.clear();
        dp.resize(n, vector<pair<int, int>>(m, {INF, -INF}));
        preprocess();
        pair<int, int> res = solve(0, m - 1);
        ans = min(ans, max(res.first - mn, mx - res.second));
        rotate();
    }
    cout << ans << '\n';
    return 0;
}

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