Scala example source code file (heapsort.scala)

This example Scala source code file (heapsort.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

array, array, double, ia, ia, ic, ic, im, im, int, unit

The Scala heapsort.scala source code

/* The Computer Language Shootout 
   http://shootout.alioth.debian.org/
   contributed by Isaac Gouy (Scala novice)
*/

object heapsort {
   def main(args: Array[String]) = {
      val n = toPositiveInt(args);

      val numbers = new Array[Double](n+1);
      for (i <- Iterator.range(1,n+1)) 
         numbers(i) = generate(100.0);

      heapsort(n, numbers);

      Console.printf("{0,number,#.000000000}\n", numbers(n));
   }


   def heapsort(n: Int, ra: Array[Double]): Unit = {
      var l = 0; var j = 0; var ir = 0; var i = 0; 
      var rra = 0.0d;

      if (n < 2) return;
      l = (n >> 1) + 1;
      ir = n;
      while (true) {
         if (l > 1) { l = l-1; rra = ra(l); }
         else {
            rra = ra(ir);
            ra(ir) = ra(1);
            ir = ir-1;
            if (ir == 1) {
               ra(1) = rra;
               return;
            }
         }
         i = l;
         j = l << 1;
         while (j <= ir) {
            if (j < ir && ra(j) < ra(j+1)) { j = j+1; }
            if (rra < ra(j)) {
               ra(i) = ra(j);
               i = j;
               j = j + i;
            } 
            else j = ir + 1;
         }
         ra(i) = rra;
      }
   }


   private val IM = 139968;
   private val IA = 3877;
   private val IC = 29573;
   private var seed = 42;

   private def generate(max: Double) = {
      seed = (seed * IA + IC) % IM;
      max * seed / IM;
   }


   private def toPositiveInt(s: Array[String]) = {
      val i = 
         try { Integer.parseInt(s(0)); } 
         catch { case _ => 1 }
      if (i>0) i; else 1;
   }

}