Submission #406680

#	Time	Username	Problem	Language	Result	Execution time	Memory
406680		cpp219	The Kingdom of JOIOI (JOI17_joioi)	C++14	100 / 100	1109 ms	125748 KiB

joioi

#include <bits/stdc++.h>
 
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
 
constexpr bool typetest = 0;
constexpr int N = 2e3 + 5;
const int Inf = 1e9 + 7;
int m, n, maxn(-Inf);
int a[N][N], b[N][N], smin[N][N], smax[N][N];
int pmin[N][N], pmax[N][N], s[N], p[N];
 
void Read()
{
    cin >> m >> n;
 
    for (int i = 1; i <= m; ++i)
        for (int j = 1; j <= n; ++j)
        {
            cin >> a[i][j];
            maxn = max(maxn, a[i][j]);
        }
}
 
bool Check(int v)
{
    for (int i = 1; i <= m; ++i)
    {
        s[i] = 0;
        p[i] = n + 1;
 
        for (int j = 1; j <= n; ++j)
            if (a[i][j] < maxn - v)
            {
                p[i] = min(p[i], j);
                s[i] = max(s[i], j);
            }
    }
 
    int maxx(-Inf), minx(Inf), piv(n + 1);
 
    for (int i = m; i; --i)
    {
        piv = min(piv, p[i]);
        maxx = max(maxx, smax[i][piv]);
        minx = min(minx, smin[i][piv]);
    }
 
    if (maxx - minx <= v)
        return true;
 
    maxx = -Inf;
    minx = Inf;
    piv = 0;
 
    for (int i = 1; i <= m; ++i)
    {
        piv = max(piv, s[i]);
        maxx = max(maxx, pmax[i][piv]);
        minx = min(minx, pmin[i][piv]);
    }
 
    return (maxx - minx <= v);
}
 
int Cal()
{
 
    for (int i = 1; i <= m; ++i)
    {
        smin[i][n + 1] = pmin[i][0] = Inf;
        smax[i][n + 1] = pmax[i][0] = -Inf;
 
        for (int j = 1; j <= n; ++j)
        {
            pmin[i][j] = min(a[i][j], pmin[i][j - 1]);
            pmax[i][j] = max(a[i][j], pmax[i][j - 1]);
        }
 
        for (int j = n; j; --j)
        {
            smin[i][j] = min(smin[i][j + 1], a[i][j]);
            smax[i][j] = max(smax[i][j + 1], a[i][j]);
        }
    }
 
    //cerr << "ok !\n";
 
    int l = 0, mid, h = maxn;
 
    while (l <= h)
    {
        mid = (l + h) / 2;
 
        if (Check(mid))
            h = mid - 1;
        else
            l = mid + 1;
    }
 
    return l;
}
 
void Solve()
{
    int ans = Cal();
 
    //cerr << "ok ? \n";
 
    for (int i = 1; i <= m; ++i)
        for (int j = 1; j <= n; ++j)
            b[n - j + 1][i] = a[i][j];
 
    swap(m, n);
 
    for (int i = 1; i <= m; ++i)
        for (int j = 1; j <= n; ++j)
            a[i][j] = b[i][j];
 
    cout << min(ans, Cal());
}
 
int32_t main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t(1);
    if (typetest)
        cin >> t;
    for (int _ = 1; _ <= t; ++_)
    {
        Read();
        Solve();
    }
}

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