Działki

#include <cstdio>
#include <stack>
#include <utility>

#define max(a, b) ((a) > (b) ? (a) : (b))
#define abs(a) ((a) > 0 ? (a) : -(a))

using namespace std;

int tab[2002][2002];
int gl[2002][2002];
stack< pair<int, int> > stos;

int main()
{
    int n, i, j, w = 0;
    scanf("%d", &n);
    for (i = 1; i <= n; i++)
    {
        for (j = 1; j <= n; j++)
        {
            scanf("%d", &tab[i][j]);
        }
        for (j = 1; j <= n; j++)
        {
            if (tab[i][j] == 0)
                gl[i][j] = gl[i-1][j]+1;
        }
    }
    /*printf("\n");
    for (i = 1; i <= n; i++)
    {
        for (j = 1; j <= n; j++)
            printf("%d ", gl[i][j]);
        printf("\n");
    }*/
    for (i = 1; i <= n+1; i++)
    {
        for (j = 1; j <= n+1; j++)
        {
            pair<int, int> last, p;
            bool bylo = false;
            if (!stos.empty())
                p = stos.top();
            while (!stos.empty() && p.second > gl[i][j])
            {
                //printf("TU (%d, %d):\n", i, j);
                w = max(w, ((j-p.first)*p.second));
                /*if (w == ((j-p.first)*p.second))
                    printf(" NOWY WYNIK - w: %d, i: %d, j: %d, j-p.first: %d\n", w, i, j, j-p.first);*/
                last = stos.top();
                stos.pop();
                bylo = true;
                if (!stos.empty())
                    p = stos.top();
            }
            if (((stos.empty() && gl[i][j] > 0) || p.second < gl[i][j]))
            {
                if (bylo)
                    stos.push(make_pair(last.first, gl[i][j]));//, printf("PUSH 1: (%d, %d)\n", last.first, gl[i][j]);
                else
                    stos.push(make_pair(j, gl[i][j]));//, printf("PUSH 2: (%d, %d)\n", j, gl[i][j]);
            }
        }
    }
    printf("%d\n", w);
    return 0;
}