public static void main(String[] strs) {

int[] height = {0};

System.out.println(largestRectangleArea(height));

}

public static int largestRectangleArea(int[] height) {

if (height == null || height.length == 0) {

return 0;

}

Stack<Integer> s = new Stack<Integer>();

int max = 0;

int len = height.length;

int i = 0;

while (i <= len) {

// BUG 1: should use height[s.peek()] instead of s.peek().

// BUG 2: should put i < length after the s.isEmpty.

// The last step: Length is also put into the stack and will break at last.

if (s.isEmpty() || (i < len && height[i] >= height[s.peek()])) {

s.push(i);

i++;

// Keep a Ascending sequence in the stack.

} else {

// Stack is not empty, and the current node is smaller than the one in the stack.

// When we come to the end of the array, we will also should count all the solutions.

// BUG 3: should use height[s.pop] instead of s.pop

// When the i come to the end, the rectangle will be counted again.

int h = height[s.pop()];

int width = s.isEmpty() ? i: i - s.peek() - 1;

max = Math.max(max, h * width);

}

}

return max;

}

}