Maximum Submatrix

最小01矩阵，Dp求解；同求最大子矩阵和类似，采用行/列存储总长度/和；

#include <iostream>
#include<cstdio>
#include<cstring>
using namespace std;

#define MAXN 2010
int h[MAXN],r[MAXN],l[MAXN];
int map[MAXN][MAXN];

char str[2];
int n,m;

void all_0_matrix()
{
    int i,j,max = 0;
    memset(h,0,sizeof(h));

    for(i = 0; i < n; i++)
    {
        for(j = 0 ; j < m; j++)
        {
            if(map[i][j] == 0)
                h[j] ++;
            else h[j] = 0;
        }

          
        for(j = 0; j < m; j ++)
        {
            l[j] = j;
            while(l[j] > 0 && h[j] <= h[l[j] - 1])
                l[j] = l[l[j] - 1];
        } 
        
        for(j = m-1; j >= 0; j --)
        {
            r[j] = j;
            while(r[j] < m-1 && h[j] <=h[r[j] + 1])
                r[j] = r[r[j] + 1];
        }


        for(j = 0; j < m; j ++)
        {
            if((r[j] - l[j] + 1) * h[j] > max)
                max = (r[j] - l[j] + 1) * h[j];
        }

    }
    printf("%d\n",max);
}
int main()
{
    int t, i , j, k, len, Case;
    char ch;
    scanf("%d",&Case );
    while( Case-- )
    {
        scanf( "%d%d", &n, &m );
        for(i = 0; i < n; i++)
        {
            for(j = 0; j < m; j++)
            {
               scanf("%d",&map[i][j]); 
            }
        }
        all_0_matrix();
    }
}