Given a 2D binary matrix filled with 0’s and 1’s, find the largest rectangle containing only 1’s and return its area.
还是单调栈,这次是二维数组,就一行一行来转化成84题的形式
public int maximalRectangle(char[][] matrix) {
if (matrix==null||matrix.length==0||matrix[0].length==0)
return 0;
int cLen = matrix[0].length; // column length
int rLen = matrix.length; // row length
// height array
int[] h = new int[cLen+1];
h[cLen]=0;
int max = 0;
for (int row=0;row<rLen;row++) {
Stack<Integer> s = new Stack<Integer>();
for (int i=0;i<cLen+1;i++) {
if (i<cLen)
if(matrix[row][i]=='1')
h[i]+=1;
else h[i]=0;
if (s.isEmpty()||h[s.peek()]<=h[i])
s.push(i);
else {
while(!s.isEmpty()&&h[i]<h[s.peek()]){
int top = s.pop();
int area = h[top]*(s.isEmpty()?i:(i-s.peek()-1));
if (area>max)
max = area;
}
s.push(i);
}
}
}
return max;
}