codeforces 22B B. Bargaining Table(dp)

题目链接：

题目大意：

题目分析：

AC代码：

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#define MAX 30

using namespace std;

int n,m;
char a[MAX][MAX];
int h[MAX][MAX];
int l[MAX][MAX];
int r[MAX][MAX];

int main ( )
{
while ( ~scanf ( "%d%d" , &n , &m ) )
{
for ( int i = 0 ; i < n ; i++ )
scanf ( "%s" , a[i] );
for ( int i = 0 ; i < n ; i++ )
for ( int j = 0 ; j < m ; j++ )
{
if ( a[i][j] == '1' )
{
h[i][j] = 0;
continue;
}
if ( i == 0 || a[i-1][j] == '1' )
h[i][j] = 1;
else h[i][j] = h[i-1][j] + 1;
}
int ans = 0;
for ( int i = 0 ; i < n ; i++ )
for ( int j = 0 ; j < m ; j++ )
for ( int k = 1 ; k <= h[i][j] ; k++ )
{
int l = j;
while ( l >= 0 && h[i][l] >= k )
l--;
ans = max ( ans , (j-l)+k );
}
printf ( "%d\n" , ans*2 );
}
}