xList = sort on x(S);
                pClosest;
                qClosest;
                Tree t = empty balanced binary tree;
                distance d = inf;
                q = left most point in xList
                foreach(Point p in x-list in order)
                {
                        t.insert(p);
                        while(q.x < p.x - d)
                        {
                                t.delete(q);
                                q = next Point in xList;
                        }
                        look at the 4 points above p
                                if(dist(p, oneOfThePoints) < d)
                                {
                                        d = dist(p, oneOfThePoints);
                                        pClosest = p;
                                        qClosest = q;
                                }
                        look at the 4 points below p
                                if(dist(q, oneOfThePoints) < d)
                                {
                                        d = dist(q, oneOfThePoints);
                                        pClosest = p;
                                        qClosest = q;
                                }
                }
                return closest pair;