Largest Rectangle in Histogram

Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the histogram.

Above is a histogram where width of each bar is 1, given height = [2,1,5,6,2,3].

The largest rectangle is shown in the shaded area, which has area = 10 unit.

For example,
Given height = [2,1,5,6,2,3],
return 10.

public class Solution {
    public int largestRectangleArea(int[] height) {
        if(height==null || height.length==0) return 0;
        
        LinkedList<Integer> s=new LinkedList<Integer>();
        int res=height[0];
        int i;
        for(i=0;i<height.length;){
            if(s.isEmpty() || height[i]>height[s.getLast()] ){
                s.add(i++);
            }
            else{
                int tmp=s.pollLast();
                res=Math.max(res,
                            height[tmp]*(s.isEmpty()?i:i-s.getLast()-1));
            }
        }
        while(!s.isEmpty()){
            int tmp=s.pollLast();
            res=Math.max(res,
                        height[tmp]*(s.isEmpty()?i:i-s.getLast()-1));
        }
        return res;
    }
}