[LeetCode] Maximal Rectangle（good）

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

参考“Largest Rectangle in Histogram”这个题的解法，思想差不多一样，只是用h向量表示Rectangle中此元素中第一行到本行的高度，非常妙的算法：

class Solution {
public:
    int maximalRectangle(vector<vector<char> > &matrix) {
        if(matrix.size() == 0 || matrix[0].size() == 0)
            return 0;
        int cLen = matrix[0].size();
        int rLen = matrix.size();
        //height array
        vector<int> h(cLen+1,0);
    
        int max = 0;

        for(int row = 0;row<rLen;row++){//for(1)
           stack<int> s;
           for(int i=0;i<cLen+1;i++){//for(2)
               if(i<cLen){
                  if(matrix[row][i]=='1')
                      h[i] += 1;
                  else
                      h[i] = 0;
               }//end if

               if(s.empty() || h[s.top()]<=h[i]){
                   s.push(i);
               }else{
                   while(!s.empty() && h[i]<h[s.top()]){
                      int top = s.top();
                      s.pop();
                      int area = h[top]*(s.empty()?i:(i-s.top()-1));
                      if(area > max)
                          max = area;
                   }//end while
                   s.push(i);
               }//end if
           }//end for(2)        
        }//end for(1)
        return max;
    }//end func
};