public int maximalRectangle(char[][] matrix){

if (matrix == null || matrix.length == 0 || matrix[0].length == 0 || matrix[0]==null) return 0;

int m = matrix.length,n = matrix[0].length,maxArea = 0;

int[] left = new int[n];

int[] right = new int[n];

int[] height = new int[n];

Arrays.fill(right,n-1);

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

int rB = n -1;

for (int j = n-1; j >= 0 ; j--) {

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

right[j] = Math.min(right[j],rB);

}else {

right[j] = n -1;

rB = j - 1;

}

}

int lB = 0;

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

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

left[j] = Math.max(left[j],lB);

height[j]++;

maxArea = Math.max(maxArea,height[j]*(right[j]-left[j]+1));

}else {

height[j] = 0;

left[j] = 0;

lB = j+1;

}

}

}

return maxArea;

}

public static void main(String[] args) {

char[][] matrix = {{'1','0','1','0','0'},

{'1','0','1','1','1'},

{'1','1','1','1','1'},

{'1','0','0','1','0'}};

MaximalRectangle maximalRectangle = new MaximalRectangle();

int r = maximalRectangle.maximalRectangle(matrix);

System.out.println(r);

}