maximalRectangle

#include<iostream>

#include<vector>

#include<algorithm>

using namespace std;

int maximalRectangle(vector<vector<char>>&matrix)

{
const int m=matrix.size();
const int n=matrix[0].size();
vector<int>h(n,0);
vector<int>l(n,0);
vector<int>r(n,n);
int ret=0;
for(int i=0;i<m;++i)
{
int left=0,right=n;
for(int j=0;j<n;++j)
{
if(matrix[i][j]=='1')
{
++h[j];
l[j]=max(l[i],left);
}
else
{
left=j+1;
h[j]=0;
l[j]=0;
r[j]=n;
}
}
for(int j=n-1;j>=0;--j)
{
if(matrix[i][j]=='1')
{
r[j]=min(r[j],right);
ret=max(ret,h[j]*(r[j]-l[j]));
}
else
{
right=j;
}
}
}
return ret;

}

int main()

{
char a1[]={'0','1','1','1'};
char a2[]={'1','0','1','1'};
char a3[]={'1','0','1','0'};
char a4[]={'0','1','0','1'};
vector<char>v1(a1,a1+sizeof(a1)/sizeof(char));
vector<char>v2(a2,a2+sizeof(a2)/sizeof(char));
vector<char>v3(a3,a3+sizeof(a3)/sizeof(char));
vector<char>v4(a4,a4+sizeof(a4)/sizeof(char));
vector<vector<char>>matrix;
matrix.push_back(v1);
matrix.push_back(v2);
matrix.push_back(v3);
matrix.push_back(v4);
cout<<maximalRectangle(matrix)<<endl;
return 0;

}