Timer.java

import java.util.Arrays;

class Timer implements Comparable<Timer> {
	public long time = 0;

	private long start = 0;

	public Timer start() {
		start = System.nanoTime();
		return this;
	}
	public Timer end() {
		time = System.nanoTime() - start;
		return this;
	}

	public String prettyTime() {
		if (time < 1000)
			return String.format("%.2fns", time);
		else if (time < 1000000)
			return String.format("%.2fμs", time / 1000f);
		else if (time < 1000000000)
			return String.format("%.2fms", time / 1000000f);
		else
			return String.format("%.2fs", time / 1000000000f);
	}

	public String prettySpeedup(Timer base) {
		double speedup = (double)base.time / (double)time;
		return String.format("%s (%.2fx speedup)",
			prettyTime(), speedup);
	}

	public static Timer median(Timer[] timers) {
		Arrays.sort(timers);
		Timer med = new Timer();

		int mid = timers.length / 2;
		if (timers.length % 2 == 0)
			med.time = (timers[mid].time + timers[mid+1].time) / 2;
		else
			med.time = timers[mid].time;

		return med;
	}

	public int compareTo(Timer t) {
		if (this.time < t.time)
			return -1;
		else if (this.time > t.time)
			return 1;
		else
			return 0;
	}
}