LeetCode: Maximal Rectangle [085]

class Solution {
public:
	
    int maximalRectangle(vector<vector<char> > &matrix) {
        int rows = matrix.size();
        if(rows==0)return 0;
        int cols = matrix[0].size();
        if(cols==0)return 0;
		
		int maxArea=0;
		
		for(int i=0; i<rows; i++){
			for(int j=0; j<cols; j++){
				if(matrix[i][j]=='1'){
					//求以该位置为左上角的最大矩形
					int minHeight=INT_MAX;
					int width=0;
					int ti=i;
					while(ti<rows && matrix[ti][j]=='1'){
						width++;
						int height=0;	//求横向高度
						while(j+height<cols && matrix[ti][j+height]=='1')height++;
						//更新最小高度
						if(height<minHeight)minHeight=height;
						//计算当前面积
						int curArea = width*minHeight;
						//更新最大面积
						if(curArea>maxArea)maxArea=curArea;
						ti++;
					}
				}
			}
		}
		return maxArea;
    }
};