playing with fibonacci sequence generators

gistfile1.java

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Fibonacci
{
  public static void main(String...args)
  {
//    fib(new BigInteger("7886"));
    fib(273000);
//    fib(new BigInteger("10"));

//    Fibocrappy.main(new String[]{"43"});
  }

  private static void fib(int steps)
  {
    long start = 0;
    long end = 0;
    List<BigInteger> fibbo = null;



//    // WARM UP
//    for (int i = 0; i < 1000; i += 1)
//    {
//      fibbo = fibberiter(steps);
//    }
//    // end WARMING



//    for (int i = 0; i < 1000; i += 1)
//    {
      start = System.nanoTime();
      fibbo = fibberiter(steps);
      end = System.nanoTime();
//      System.out.println(fibbo);
//      System.out.println(fibbo.get(fibbo.size()-1));
//    }
    System.out.println("time took: " + ((end - start)/1000000.0F) + "ms");



//    for (int i = 0; i < 1000; i += 1)
//    {
//      start = System.nanoTime();
//      fibbo = fibbertail(BigInteger.ZERO,BigInteger.ONE,steps,null);
//      end = System.nanoTime();
////      System.out.println(fibbo);
////      System.out.println(fibbo.get(fibbo.size()-1));
//    }
//    System.out.println("time took: " + ((end - start)/1000000.0F) + "ms");



//    for (int i = 0; i < 1000; i += 1)
//    {
//      start = System.nanoTime();
//      fibbo = fibber(BigInteger.ZERO,BigInteger.ONE,steps);
//      end = System.nanoTime();
////      System.out.println(fibbo);
////      System.out.println(fibbo.get(fibbo.size()-1));
//    }
//    System.out.println("time took: " + ((end - start)/1000000.0F) + "ms");



  }

  private static List<BigInteger> fibberiter(int steps)
  {
    List<BigInteger> result = new ArrayList<BigInteger>(steps);

    BigInteger a = BigInteger.ZERO;
    BigInteger b = BigInteger.ONE;

    for (int i = 0; i < steps; i += 1)
    {
      try
      {
        result.add(a);
        BigInteger ab = null;
        ab = a.add(b);
        a = b;
        b = ab;
      }
      catch (OutOfMemoryError e)
      {
        System.out.println(i);
//        throw e;
        e.printStackTrace();
        return null;
      }
    }

    return result;
  }

  private static List<BigInteger> fibber(BigInteger a, BigInteger b, BigInteger step)
  {
    List<BigInteger> result = new ArrayList<BigInteger>();

    if (step.compareTo(BigInteger.ZERO) > 0)
    {
      step = step.subtract(BigInteger.ONE);
      result.add(a);
      result.addAll(fibber(b, a.add(b), step));
    }

    return result;
  }

  private static List<BigInteger> fibbertail(BigInteger a, BigInteger b, int steps, List<BigInteger> list)
  {
    if (list == null) list = new ArrayList<BigInteger>(steps);
    list.add(a);
    try
    {
      return (steps == 0) ? Collections.<BigInteger>emptyList() : (list.size() >= steps) ? list : fibbertail(b, a.add(b), steps, list);
    }
    catch (StackOverflowError e)
    {
      System.out.println(list.size());
//      throw e;
      e.printStackTrace();
      return null;
    }
  }

  /**
   * stole online as reference for crappy implementation
   */
  public static class Fibocrappy {
    public static long fib(int n) {
        if (n <= 1) return n;
        else return fib(n-1) + fib(n-2);
    }

    public static void main(String[] args) {
        int N = Integer.parseInt(args[0]);
        for (int i = 1; i <= N; i++)
            System.out.println(i + ": " + fib(i));
    }
  }
}