Scala example source code file (binarytrees.scala)

This example Scala source code file (binarytrees.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, empty, empty, int, int, node, node, string, tree, tree

The Scala binarytrees.scala source code

/*
  The Computer Language Shootout
  http://shootout.alioth.debian.org/

  - tree: disjoint union type
  - loop: "for" loop over iterator range

  Contributed by Kannan Goundan
  De-optimized by Isaac Gouy
*/

object binarytrees {

  abstract class Tree;
  case class Node(i: Int, left: Tree, right: Tree) extends Tree
  case class Empty() extends Tree

  def check(tree: Tree) : Int = tree match {
    case Node(i, left, right) => i + check(left) - check(right)
    case Empty() => 0
  }

  def make(i: Int, depth: Int) : Tree = depth match {
/*  case 0 => Empty() */
    case 0 => Node(i, Empty(), Empty())
    case _ => Node(i, make((2*i)-1, depth-1), make(2*i, depth-1))
  }

  def main(args: Array[String]) = {
    val n = try { Integer.parseInt(args(0)) } catch { case _ => 1 }
    val minDepth = 4
    val maxDepth = Math.max(minDepth+2, n)

    print("stretch tree", maxDepth+1, check(make(0, maxDepth+1)))

    val longLived = make(0, maxDepth)

    for (val depth <- Iterator.range(minDepth, maxDepth+1, 2)) {
      val iterations = 1 << (maxDepth - depth + minDepth)

      var sum = 0
      for (val i <- Iterator.range(1, iterations+1))
        sum = sum + check(make(i, depth)) + check(make(-i, depth))

      print(iterations*2 + "\t trees", depth, sum)
    }

    print("long lived tree", maxDepth, check(longLived))
  }

  def print(name: String, depth: Int, check: Int) =
    Console.println(name + " of depth " + depth + "\t check: " + check)
}