Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area.
public class Solution {
public int maximalRectangle(char[][] matrix) {
if (matrix == null || matrix.length <= 0 || matrix[0].length <= 0) {
return 0;
}
int rows = matrix.length;
int cols = matrix[0].length;
int[] height = new int[cols];
int[] left = new int[cols];
int[] right = new int[cols];
int max = 0;
for (int i = 0; i < cols; i++) {
right[i] = cols;
}
for (int i = 0; i < rows; i++) {
int curLeft = 0;
int curRight = cols;
for (int j = 0; j < cols; j++) {
if (matrix[i][j] == '1') {
height[j]++;
left[j] = Math.max(curLeft, left[j]);
} else {
height[j] = 0;
curLeft = j + 1;
left[j] = 0;
}
}
for (int j = cols - 1; j >= 0; j--) {
if (matrix[i][j] == '1') {
right[j] = Math.min(curRight, right[j]);
} else {
right[j] = cols;
curRight = j;
}
max = Math.max(max, (right[j] - left[j]) * height[j]);
}
}
return max;
}
}