LeetCode_Maximal Rectangle

Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area.

　　

class Solution {

public:

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

        // Start typing your C/C++ solution below

        // DO NOT write int main() function

         // DO NOT write int main() function

        int m = matrix.size();

        if(m < 1) return 0;

        int n = matrix[0].size();

        

        vector<int> cache(m, 0);

        int i,j,area, maxArea = 0,top;

        stack<int> s;

        



        for(i = n; i>= 0; i--)

        {

            for(int k = 0; k< m; k++)

              if(matrix[k][i] == '1')

                   cache[k] ++ ;

                else 

                   cache[k] = 0;

                   

            for(j= 0; j< m; )

            {

                 if(s.empty() || cache[j] >= cache[s.top()] )

                   {

                        s.push(j);

                        j++;

                        continue;

                   }else{

                          top = s.top();

                          s.pop();

                          area = cache[top] * ( s.empty() ? j : j - s.top() -1);

                          maxArea = maxArea > area ? maxArea : area ;

                

                   }

            }

            

            while(!s.empty())

            {

                top = s.top();

                s.pop();

                area = cache[top] * ( s.empty() ? j : j - s.top() -1);

                maxArea = maxArea > area ? maxArea : area ;

            }

        }

        

        return maxArea ;

        

    }

};