public static void main(String[] args){

int[] input = {4,2,0,3,2,5};

int result = largestRectangleArea(input);

System.out.printf("Result: %d\n", result);

}

public static int largestRectangleArea(int[] height) {

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

return 0;

}

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

int rightBoard = 0;

int maxArea = 0;

stack.push(rightBoard);

for (rightBoard = 1; rightBoard <= height.length; rightBoard ++){

int leftBoard;

int h;

int wide;

int currentHeight = 0;

if (rightBoard < height.length){

currentHeight = height[rightBoard];

}

while (!stack.empty() && currentHeight < height[stack.peek()]){

/* get the left board of the rectangle. */

leftBoard = stack.pop();

h = height[leftBoard];

if (stack.empty()){

wide = rightBoard;

}else{

//wide = rightBoard - leftBoard;

wide = rightBoard - stack.peek() -1;

}

System.out.printf("area: %d, h:%d, w:%d\n", h*wide, h, wide);

maxArea = Math.max(maxArea, h*wide);

}

stack.push(rightBoard);

}

return maxArea;

}