Submission #1258939

#	Time	Username	Problem	Language	Result	Execution time	Memory
1258939		DangKhoizzzz	The Kingdom of JOIOI (JOI17_joioi)	C++20	100 / 100	2524 ms	63300 KiB

joioi

#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define pii pair <int , int>
#define arr3 array <int , 3>

using namespace std;

const int INF = 1e18;
const int maxn = 2e3 + 7;


int n , m , a[maxn][maxn] , maxval = 0 , b[maxn][maxn];

void rotate() // xoay 90
{
    for(int i = 1; i <= m; i++)
    {
        for(int j = 1; j <= n; j++) b[i][j] = a[n-j+1][i];
    }
    swap(n , m);
    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= m; j++) a[i][j] = b[i][j];
    }
}

bool good(int mid)
{
    int last = INF , mx = 0 , mn = INF;
    for(int i = 1; i <= n; i++) 
    {
        int j = 0; while(j < m && a[i][j+1] >= maxval - mid) j++;
        j = min(j , last);
        last = j;
        for(int x = j+1; x <= m; x++) 
        {
            mx = max(mx , a[i][x]);
            mn = min(mn , a[i][x]);
        }
    }
    return (mx == 0 || mx - mn <= mid);
}

bool check(int mid)
{
    bool ans = 0;
    ans = max(ans , good(mid)); rotate();
    ans = max(ans , good(mid)); rotate();
    ans = max(ans , good(mid)); rotate();
    ans = max(ans , good(mid)); rotate();
    return ans;
}

void solve()
{
    cin >> n >> m;
    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= m; j++)
        {
            cin >> a[i][j];
            maxval = max(maxval , a[i][j]);
        }
    }

    int l = 0 , r = 1e9 , ans = 1e9;
    while(l <= r)
    {
        int mid = (l+r)>>1;
        if(check(mid))
        {
            ans = mid;
            r = mid - 1;
        }
        else l = mid + 1;
    }
    cout << ans << '\n';
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    solve();
    return 0;
}

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