leetcode[85]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 largestRectangleArea(vector<int> &height) 

{

    if(height.empty())return 0;

    height.push_back(0);

    int maxRes=0;

    stack<int> sta;

    for (int i=0;i<height.size();i++)

    {

        int top;

        int newRes;

        while(!sta.empty()&&height[i]<height[sta.top()])

        {

            top=sta.top();

            sta.pop();

            newRes=(sta.empty()?i:(i-sta.top()-1))*height[top];

            maxRes=maxRes>newRes?maxRes:newRes;                

        }

        sta.push(i);

    }

    return maxRes;

}

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

{

    if(matrix.empty())return 0;

    int m=matrix.size();

    if(matrix[0].empty())return 0;

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

    int maximal=0;

    vector<vector<int>> d(m,vector<int> (n));

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

    {

        for(int j=0;j<n;j++)

        {

            if(i==0)d[i][j]=matrix[i][j]-'0';

            else 

            {

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

                {

                    d[i][j]=d[i-1][j]+matrix[i][j]-'0';

                }

                else

                {

                    d[i][j]=matrix[i][j]-'0';

                }

            }

        }

        int tmp=largestRectangleArea(d[i]);

        maximal=maximal>tmp?maximal:tmp;

    }

    return maximal;

}

};