Submission #678839

#	Time	Username	Problem	Language	Result	Execution time	Memory
678839		bebra	The Kingdom of JOIOI (JOI17_joioi)	C++17	0 / 100	16 ms	4292 KiB

joioi

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

#define dbg(x) cerr << #x << ": " << x << endl;

const int MAX_N = 2000 + 5;
int grid[MAX_N][MAX_N];
bool used[MAX_N][MAX_N];


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            cin >> grid[i][j];
        }
    }
    auto check = [&](int x) {
        bool ok = false;
        {
            int first_min = 1e9;
            int first_max = 0;
            int last_used = m - 1;
            for (int i = 0; i < n; ++i) {
                int prev_used = last_used;
                for (int j = 0; j <= prev_used; ++j) {
                    int curr_min = min(first_min, grid[i][j]);
                    int curr_max = max(first_max, grid[i][j]);
                    if (curr_max - curr_min > x) {
                        break;
                    } else {
                        first_min = curr_min;
                        first_max = curr_max;
                        last_used = j;
                        used[i][j] = true;
                    }
                }
            }
            int second_min = 1e9;
            int second_max = 0;
            for (int i = 0; i < n; ++i) {
                for (int j = 0; j < m; ++j) {
                    if (!used[i][j]) {
                        second_min = min(second_min, grid[i][j]);
                        second_max = max(second_max, grid[i][j]);
                    }
                }
            }
            memset(used, 0, sizeof(used));
            ok |= second_max - second_min <= x;
        }
        {
            int first_min = 1e9;
            int first_max = 0;
            int last_used = n - 1;
            for (int j = 0; j < m; ++j) {
                int prev_used = last_used;
                for (int i = 0; i <= prev_used; ++i) {
                    int curr_min = min(first_min, grid[i][j]);
                    int curr_max = max(first_max, grid[i][j]);
                    if (curr_max - curr_min > x) {
                        break;
                    } else {
                        first_min = curr_min;
                        first_max = curr_max;
                        last_used = i;
                        used[i][j] = true;
                    }
                }
            }
            int second_min = 1e9;
            int second_max = 0;
            for (int i = 0; i < n; ++i) {
                for (int j = 0; j < m; ++j) {
                    if (!used[i][j]) {
                        second_min = min(second_min, grid[i][j]);
                        second_max = max(second_max, grid[i][j]);
                    }
                }
            }
            memset(used, 0, sizeof(used));
            ok |= second_max - second_min <= x;
        }
        {
            int first_min = 1e9;
            int first_max = 0;
            int last_used = 0;
            for (int i = 0; i < n; ++i) {
                int prev_used = last_used;
                for (int j = m - 1; j >= prev_used; --j) {
                    int curr_min = min(first_min, grid[i][j]);
                    int curr_max = max(first_max, grid[i][j]);
                    if (curr_max - curr_min > x) {
                        break;
                    } else {
                        first_min = curr_min;
                        first_max = curr_max;
                        last_used = j;
                        used[i][j] = true;
                    }
                }
            }
            int second_min = 1e9;
            int second_max = 0;
            for (int i = 0; i < n; ++i) {
                for (int j = 0; j < m; ++j) {
                    if (!used[i][j]) {
                        second_min = min(second_min, grid[i][j]);
                        second_max = max(second_max, grid[i][j]);
                    }
                }
            }
            memset(used, 0, sizeof(used));
            ok |= second_max - second_min <= x;
        }
        {
            int first_min = 1e9;
            int first_max = 0;
            int last_used = n - 1;
            for (int j = m - 1; j >= 0; --j) {
                int prev_used = last_used;
                for (int i = 0; i <= prev_used; ++i) {
                    int curr_min = min(first_min, grid[i][j]);
                    int curr_max = max(first_max, grid[i][j]);
                    if (curr_max - curr_min > x) {
                        break;
                    } else {
                        first_min = curr_min;
                        first_max = curr_max;
                        last_used = i;
                        used[i][j] = true;
                    }
                }
            }
            int second_min = 1e9;
            int second_max = 0;
            for (int i = 0; i < n; ++i) {
                for (int j = 0; j < m; ++j) {
                    if (!used[i][j]) {
                        second_min = min(second_min, grid[i][j]);
                        second_max = max(second_max, grid[i][j]);
                    }
                }
            }
            memset(used, 0, sizeof(used));
            ok |= second_max - second_min <= x;
        }
        {
            int first_min = 1e9;
            int first_max = 0;
            int last_used = 0;
            for (int i = n - 1; i >= 0; --i) {
                int prev_used = last_used;
                for (int j = m - 1; j >= prev_used; --j) {
                    int curr_min = min(first_min, grid[i][j]);
                    int curr_max = max(first_max, grid[i][j]);
                    if (curr_max - curr_min > x) {
                        break;
                    } else {
                        first_min = curr_min;
                        first_max = curr_max;
                        last_used = j;
                        used[i][j] = true;
                    }
                }
            }
            int second_min = 1e9;
            int second_max = 0;
            for (int i = 0; i < n; ++i) {
                for (int j = 0; j < m; ++j) {
                    if (!used[i][j]) {
                        second_min = min(second_min, grid[i][j]);
                        second_max = max(second_max, grid[i][j]);
                    }
                }
            }
            memset(used, 0, sizeof(used));
            ok |= second_max - second_min <= x;
        }
        return ok;
    };
    int l = -1;
    int r = 1e9;
    while (l != r - 1) {
        int mid = (l + r) / 2;
        if (check(mid)) {
            r = mid;
        } else {
            l = mid;
        }
    }
    cout << r << '\n';
    return 0;
}

• Subtask 1: 0 / 15
• Subtask 2: 0 / 45
• Subtask 3: 0 / 40