Submission #1258924

#	Time	Username	Problem	Language	Result	Execution time	Memory
1258924		DangKhoizzzz	The Kingdom of JOIOI (JOI17_joioi)	C++20	0 / 100	0 ms	320 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 dx[4] = {-1 , 1 , 0 , 0};
int dy[4] = {0 , 0 , -1 , 1};


int n , m , a[maxn][maxn] , b[maxn][maxn];
pii mxpos = {0 , 0};

bool in(int i , int j) {return (1 <= i && i <= n && 1 <= j && j <= m);}

void dfs(int i , int j , int lim)
{
    b[i][j] = 1;
    for(int k = 0; k < 4; k++)
    {
        int x = i + dx[k] , y = j + dy[k];
        if(in(x , y) && b[x][y] == 0 && a[x][y] >= lim)
        {
            dfs(x , y , lim);
        }
    }
}

bool check(int mid)
{
    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= m; j++) b[i][j] = 0;
    }
    dfs(mxpos.fi , mxpos.se , a[mxpos.fi][mxpos.se] - mid);

    // for(int i = 1; i <= n; i++) 
    // {
    //     for(int j = 1; j <= m; j++) cout << b[i][j] << ' ';
    //     cout << '\n';
    // }

    int mx = 0 , mn = INF , last = INF;

    for(int i = 1; i <= n; i++)
    {
        int c = 0;
        while(c < m && b[i][c+1] == 1) c++;
        c = min(c , last);
        for(int j = c+1; j <= m; j++)
        {
            mx = max(mx , a[i][j]);
            mn = min(mn , a[i][j]);
        }
    }
    if(mx - mn <= mid || mx == 0) 
    {
        return 1;
    }

    mx = 0 , mn = INF , last = INF;

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

    mx = 0 , mn = INF , last = 0;

    for(int i = 1; i <= n; i++)
    {
        int c = m+1;
        while(c > 1 && b[i][c-1] == 1) c--;
        c = max(c , last);
        for(int j = 1; j < c; j++)
        {
            mx = max(mx , a[i][j]);
            mn = min(mn , a[i][j]);
        }
    }

    if(mx - mn <= mid || mx == 0) 
    {
        return 1;
    }

    mx = 0 , mn = INF , last = 0;

    for(int i = n; i >= 1; i--)
    {
        int c = m+1;
        while(c > 1 && b[i][c-1] == 1) c--;
        c = max(c , last);
        for(int j = 1; j < c; j++)
        {
            mx = max(mx , a[i][j]);
            mn = min(mn , a[i][j]);
        }
    }

    if(mx - mn <= mid || mx == 0) return 1;
    return 0;
}

void solve()
{
    cin >> n >> m;
    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= m; j++)
        {
            cin >> a[i][j];
            if(a[i][j] >= a[mxpos.fi][mxpos.se]) mxpos = (pii){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: 0 / 15
• Subtask 2: 0 / 45
• Subtask 3: 0 / 40