Scala example source code file (recursive.scala)

This example Scala source code file (recursive.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

ack, array, array, double, double, fib, fib, int, int, tak, thread

The Scala recursive.scala source code

/*
 * The Computer Language Shootout
 * http://shootout.alioth.debian.org/
 *
 * contributed by Andrei Formiga
 */

object recursive
{
  def ack(x: Int, y: Int): Int =
    if (x == 0) y + 1 
    else if (y == 0) ack(x - 1, 1) 
    else ack(x - 1, ack(x, y - 1))

  def fib(n: Int): Int =
    if (n < 2) 1 else fib(n - 2) + fib(n - 1)

  def fib(n: Double): Double =
    if (n < 2.0) 1.0 else fib(n - 2.0) + fib(n - 1.0)

  def tak(x: Int, y: Int, z: Int): Int =
    if (y < x) tak(tak(x - 1, y, z), tak(y - 1, z, x), tak(z - 1, x, y))
    else z

  def tak(x: Double, y: Double, z: Double): Double = 
    if (y < x)  tak(tak(x - 1.0, y, z), tak(y - 1.0, z, x), tak(z - 1.0, x, y)) 
    else z

  def main(args: Array[String]) {
    var n = Integer.parseInt(args(0))

    // spawn a new thread fixes stack overflows on Windows 1.5 JDK
    // see more on ticket #1508
    val t = new Thread {
      override def run {
	Console.println("Ack(3," + n + "): " + ack(3, n))
	Console.printf("Fib(%.1f): %.1f\n", (27.0+n), fib(27.0+n))
	n = n - 1
	Console.println("Tak(" + (3*n) + "," + (2*n) + "," + n + "): " + tak(3*n, 2*n, n))
	Console.println("Fib(3): " + fib(3))
	Console.println("Tak(3.0,2.0,1.0): " + tak(3.0,2.0,1.0))
      }
    }
    t.start()
    t.join()
  }
}