public class FastClosestPair {

	public final static double INF = java.lang.Double.POSITIVE_INFINITY;

	public static PointPair closestPair(XYPoint[] points) {
		XYPoint pointsByX[] = new XYPoint[points.length];
		XYPoint pointsByY[] = new XYPoint[points.length];
		for (int j = 0; j < points.length; j++) {
			pointsByX[j] = points[j];
			pointsByY[j] = points[j];
		}

		// Ensure sorting precondition for divide-and-conquer algorithm.
		XComparator xcomp = new XComparator();
		YComparator ycomp = new YComparator();
		Sort.msort(pointsByX, xcomp); // sort by x-coord
		Sort.msort(pointsByY, ycomp); // sort by y-coord
		return findClosestPair(pointsByX, pointsByY);
	}

	static PointPair findClosestPair(XYPoint[] pointsByX, XYPoint[] pointsByY) {
//  You need to write this method.  I've put something in so that there
//    are no compiler or runtime errors.  You'll want to replace this line.
		return new PointPair(null,null,INF);
	}
}