import java.lang.*;
import java.util.*;

public class RandomTime {

    private static void useRandom(int n) {
	Random r = new Random();
	int t = 0;
	long t1 = System.nanoTime();
	for (int i = 0; i < n; i++) t += r.nextInt();
	long t2 = System.nanoTime();
	System.out.println((t2-t1) + " nsec for " + n + " giving " + t);
    }

    private static void dblRandom(int n) {
	Random r = new Random();
	double t = 0.0;
	long t1 = System.nanoTime();
	for (int i = 0; i < n; i++) t += r.nextDouble();
	long t2 = System.nanoTime();
	System.out.println((t2-t1) + " nsec for " + n + " giving " + t);
    }

    private static void bulkRandom(int n) {
	Random r = new Random();
	byte[] b = new byte[128];
	long t1 = System.nanoTime();
	for (int i = 0; i < n; i++) r.nextBytes(b);
	long t2 = System.nanoTime();
	System.out.println((t2-t1) + " nsec for " + n + " giving " +
			    b.toString());
    }

    private static void useRandom48(int n) {
	Random48 r = new Random48();
	int t = 0;
	long t1 = System.nanoTime();
	for (int i = 0; i < n; i++) t += r.nextInt();
	long t2 = System.nanoTime();
	System.out.println((t2-t1) + " nsec for " + n + " giving " + t);
	String s = r.toString();
    }

    private static void dblRandom48(int n) {
	Random48 r = new Random48();
	double t = 0.0;
	long t1 = System.nanoTime();
	for (int i = 0; i < n; i++) t += r.nextDouble();
	long t2 = System.nanoTime();
	System.out.println((t2-t1) + " nsec for " + n + " giving " + t);
	String s = r.toString();
    }

    private static void bulkRandom48(int n) {
	Random48 r = new Random48();
	byte[] b = new byte[128];
	long t1 = System.nanoTime();
	for (int i = 0; i < n; i++) r.nextBytes(b);
	long t2 = System.nanoTime();
	System.out.println((t2-t1) + " nsec for " + n + " giving " +
			    b.toString());
    }

    public static void main(String[] args) {
        System.out.println("ints\n");
	useRandom(    1000000);
	useRandom48(  1000000);
	useRandom(   10000000);
	useRandom48( 10000000);
	useRandom(  100000000);
	useRandom48(100000000);

        System.out.println("\ndoubles\n");
	dblRandom(    1000000);
	dblRandom48(  1000000);
	dblRandom(   10000000);
	dblRandom48( 10000000);
	dblRandom(  100000000);
	dblRandom48(100000000);

        System.out.println("\nbytes\n");
	bulkRandom(    10000);
	bulkRandom48(  10000);
	bulkRandom(   100000);
	bulkRandom48( 100000);
	bulkRandom(  1000000);
	bulkRandom48(1000000);
    }

    // The results are
    // 3.3 ns/int
    // 6.9 ns/double
    // 0.9 ns/byte (array of 128 bytes)
    // all running about 5.2 times faster than java.util.Random
    // Compiled using javac 1.6.0_26 on a 2.66 GHz Intel Core 2 Duo
    // with 4 GB 1067 MHz DDR3 memory running Mac OS X 10.6.8;
    // run using java 1.6.0_26 in -server mode on the same machine.
}