Submission #396949

#	Time	Username	Problem	Language	Result	Execution time	Memory
396949		timmyfeng	The Kingdom of JOIOI (JOI17_joioi)	C++17	100 / 100	731 ms	44144 KiB

joioi

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

const int N = 2001;

int prefix[N], suffix[N], diff[N][N], a[N][N];

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m;
    cin >> n >> m;

    int maxi = INT_MIN, mini = INT_MAX;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            cin >> a[i][j];
            maxi = max(maxi, a[i][j]);
            mini = min(mini, a[i][j]);
        }
    }

    fill(diff[0], diff[0] + m + 1, INT_MIN);
    int ans = INT_MAX;

    for (int k = 0; k < 2; ++k) {
        for (int i = 0; i < n; ++i) {
            reverse(a[i], a[i] + m);
        }

        for (int l = 0; l < 2; ++l) {
            reverse(a, a + n);

            for (int i = 0; i < n; ++i) {
                copy(a[i], a[i] + m, prefix);
                for (int j = 1; j < m; ++j) {
                    prefix[j] = min(prefix[j], prefix[j - 1]);
                }

                copy(a[i], a[i] + m, suffix);
                for (int j = m - 2; j >= 0; --j) {
                    suffix[j] = max(suffix[j], suffix[j + 1]);
                }

                for (int j = 0; j <= m; ++j) {
                    diff[i + 1][j] = max({
                        j > 0 ? maxi - prefix[j - 1] : INT_MIN,
                        j < m ? suffix[j] - mini : INT_MIN,
                        diff[i][j]
                    });

                    if (j > 0) {
                        diff[i + 1][j] = min(diff[i + 1][j], diff[i + 1][j - 1]);
                    }
                }
            }

            ans = min(ans, *min_element(diff[n], diff[n] + m + 1));
        }
    }

    cout << ans << "\n";
}

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