Submission #376539

#	Time	Username	Problem	Language	Result	Execution time	Memory
376539		smjleo	The Kingdom of JOIOI (JOI17_joioi)	C++14	15 / 100	9 ms	1772 KiB

joioi

#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
using namespace std;
#define int long long
#define nl '\n'
#define io ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
const int mod = 1000000007, mod2 = 998244353;

// change this
const int N = 2005;

int n, m, arr[N][N], k, mini = INT_MAX, maxi = INT_MIN;

bool can() {
    int ffp = 1e9;
    // confirm leftmost corner
    for (int i=0; i<n; i++) {
        // find first place where element > mini+k
        int fp = n;
        for (int j=0; j<m; j++) {
            if (arr[i][j] > mini + k) {
                fp = j;
                break;
            }
        }
        ffp = min(ffp, fp);
        // find last place where element < maxi-k
        int lp = -1;
        for (int j=m-1; j>=0; j--) {
            if (arr[i][j] < maxi - k) {
                lp = j;
                break;
            }
        }
        if (ffp <= lp) return false;
    }
    return true;
}

void flipr() {
    for (int i=0; i<n; i++) reverse(arr[i], arr[i]+m);
}

void flipc() {
    for (int i=0; i<m; i++) {
        for (int j=0; j<n/2; j++) swap(arr[j][i], arr[n-j-1][i]);
    }
}

int verify(int kk) {
    k = kk;

    if (can()) return true;
    flipr();
    if (can()) return true;
    flipc();
    if (can()) return true;
    flipr();
    if (can()) return true;
    flipc();
    
    return false;
}

signed main() {
    io;
    cin >> n >> m;
    for (int i=0; i<n; i++) {
        for (int j=0; j<m; j++) {
            cin >> arr[i][j];
            mini = min(mini, arr[i][j]);
            maxi = max(maxi, arr[i][j]);
        }
    }

    int l = 0, r = 1e9+5;
    while (l<r) {
        int mid = (l+r)/2;
        if (verify(mid)) r = mid;
        else l = mid+1;
    }
    cout << l << nl;
}

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