Submission #1067154

#	Time	Username	Problem	Language	Result	Execution time	Memory
1067154		phoenix	The Kingdom of JOIOI (JOI17_joioi)	C++17	100 / 100	327 ms	54772 KiB

joioi

#include <bits/stdc++.h>

using namespace std;

const int NAX_N = 2020;

int n, m;
int a[NAX_N][NAX_N];

int mn_r, mn_c;

bool check0(int d) {
    int prev = m;
    int mn = 1e9, mx = -1e9;
    for (int r = 0; r < n; r++) {
        int c = 0;
        while (c < prev && a[r][c] <= a[mn_r][mn_c] + d) 
            c++;
        if (r <= mn_r && c <= mn_c) 
            return false;   
        prev = c;
        while (c < m) {
            mn = min(mn, a[r][c]);
            mx = max(mx, a[r][c]);
            c++;
        }
    }
    return mn + d >= mx;
}

bool check1(int d) {
    int prev = -1;
    int mn = 1e9, mx = -1e9;
    for (int r = n - 1; r >= 0; r--) {
        int c = m - 1;
        while (c > prev && a[r][c] <= a[mn_r][mn_c] + d)
            c--;
        if (r >= mn_r && c >= mn_c)
            return false;
        prev = c;
        while (c >= 0) {
            mn = min(mn, a[r][c]);
            mx = max(mx, a[r][c]);
            c--;
        }
    }
    return mn + d >= mx;
}

bool check2(int d) {
    int prev = m;
    int mn = 1e9, mx = -1e9;
    for (int r = n - 1; r >= 0; r--) {
        int c = 0;
        while (c < prev && a[r][c] <= a[mn_r][mn_c] + d)
            c++;
        if (r >= mn_r && c <= mn_c)
            return false;
        prev = c;
        while (c < m) {
            mn = min(mn, a[r][c]);
            mx = max(mx, a[r][c]);
            c++;
        }
    }
    return mn + d >= mx;
}

bool check3(int d) {
    int prev = -1;
    int mn = 1e9, mx = -1e9;
    for (int r = 0; r < n; r++) {
        int c = m - 1;
        while (c > prev && a[r][c] <= a[mn_r][mn_c] + d)
            c--;
        if (r <= mn_r && c >= mn_c)
            return false;
        prev = c;
        while (c >= 0) {
            mn = min(mn, a[r][c]);
            mx = max(mx, a[r][c]);
            c--;
        }
    }
    return mn + d >= mx;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++) {
            cin >> a[i][j];
            if (a[i][j] < a[mn_r][mn_c]) {
                mn_r = i;
                mn_c = j;
            }
        }

    int l = -1, r = 1e9;
    while (r - l > 1) {
        int m = (l + r) / 2;
        if (check0(m) || check1(m) 
         || check2(m) || check3(m))
            r = m;
        else 
            l = m;
    }
    cout << r;
}

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