Maximal Rectangle [LeetCode]

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

Basic idea: To increas one dimension by one, then calculate the maximum of other dimension every time.

class Solution {
public:
    int maximalRectangle(vector<vector<char> > &matrix) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(matrix.size() == 0 || matrix[0].size() == 0)
            return 0;
        int max_area = 0;
        int row = matrix.size();
        int column = matrix[0].size();
        for(int i = 0; i < row; i ++) {
            for( int j = 0; j < column; j ++) {
                if (matrix[i][j] == '0')
                    continue;
                
                int tmp_area = 1;
                int max_row_idx = row - 1;
                int max_column_idx = j;
                while(max_column_idx < column){
                    int l;
                    for(l = i + 1; l <= max_row_idx; l ++){
                         if (matrix[l][max_column_idx] == '0') 
                            break;
                    }
                    max_row_idx = l - 1;
                    tmp_area = (max_row_idx - i + 1) * (max_column_idx - j + 1);
                    if(tmp_area > max_area)
                        max_area = tmp_area;
                    
                    //increase column
                    if ( matrix[i][max_column_idx + 1] == '1'){
                        max_column_idx ++;
                    }else{
                        break;
                    }
                }
                
            }
        }
        return max_area;
    }
};