package LeetCode;

import java.util.Stack;

public class MaximalRectangle {

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;

}

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;

}

}

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;

}

}