maximal-rectangle

自己做个笔记用

public class Solution{
    public int maximalRectangle(char[][] matrix){
        if(matrix==null || matrix.length==0 || matrix[0].length==0)
        return 0;
        int[] height = new int[matrix[0].length];
        for(int i==0;i<matrix[0].length;i++){
            if(matrix[0][i]=="1")
            height[i]==1;
        }
        int result=largestInLine(height);
        for(int i=1;i<matrix.length;i++){
            resetHeight(matrix,height,i);
            result=Math.max(result,largestInLine(height));
        }
        return result;
    }
    //为每行维护的数组，用于储存高度
    public int largestInLine(int[] height){
        if(height==null || height.length==0)
        return 0;
        int len=height.length;
        Stack<Integer> s=new Stack<Integer>();
        int maxArea=0;
        for(int i=0; i<=len;i++){
            int h=(i==len?0:height[i]);
            if(s.isEmpty() || h>=height[s.peek()]){
                s.push(i);
            }else{
                int tp=s.pop();
                maxArea=Math.max(maxArea,height[tp]*(s.isEmpty()?i:i-1-s.peek()));
                i--；
            }
        }
        return maxArea;
    }
    //重置高度，用以扫描整个矩阵
    private void resetHeight(char[][] matrix,int[] height,int idx){
        for(int i=0;i<matrix[0].length;i++){
            if(matrix[idx][i]=='1')
            height[i]+=1;
            else
            height[i]=0;
        }
    }
}