Convex Hull

/**
 * Get the convex of a graph
 * default is exclusive, see comments for inclusivity
 * @param in input
 * @return output
 */
public ArrayList<Point> convexHull(ArrayList<Point> in){//default is exclusive, see 2 comments for inclusivity
	LinkedList<Point> out=new LinkedList<Point>();
	Point temp=new Point(0,Integer.MAX_VALUE);
	for(Point p:in)if(p.y<temp.y||(p.y==temp.y&&p.x<temp.x))temp=p;
	final Point min=new Point(temp);
	TreeSet<Point> pq=new TreeSet<Point>(new Comparator<Point>(){
		public int compare(Point p0, Point p1) {
			double temp=Math.atan2(p0.y-min.y,p0.x-min.x)-Math.atan2(p1.y-min.y,p1.x-min.x);
			if(temp<0||(temp==0&&min.distance(p0)<min.distance(p1)))return -1;
			return 1;
		}
	});
	out.add(min);
	for(Point p:in)if(!p.equals(min))pq.add(p);
	while(!pq.isEmpty()){
		if(out.size()<2)out.add(pq.pollFirst());
		if(pq.isEmpty())break;//this line only necessary for degenerate case
		Point m=out.getLast(),n=out.get(out.size()-2),o=pq.first();
		if((m.x-n.x)*(o.y-m.y)-(o.x-m.x)*(m.y-n.y)>0)out.add(pq.pollFirst());//take left hand turn only, change to >= for inclusivity
		else out.remove(out.size()-1);
	}
/*		ArrayList<Point> tail=new ArrayList<Point>();//this block is only needed for inclusivity
	for(Point p:in)if(!p.equals(min)&&(p.x-min.x)*(out.getLast().y-p.y)-(out.getLast().x-p.x)*(p.y-min.y)==0)tail.add(p);
	Collections.sort(tail, new Comparator<Point>(){
		public int compare(Point p0, Point p1) {
			return Double.compare(min.distance(p1),min.distance(p0));
		}
	});
	out.removeLast();
	out.addAll(tail);*/
	return new ArrayList<Point>(out);
}