Euler, ex. 1 Scala.scala

/* If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9.
   The sum of these multiples is 23.
   Find the sum of all the multiples of 3 or 5 below 1000.
*/

// List comprehension
object ex1_a {
  val multiples = for (i <- List.range(1, 1000) if i % 3 == 0 || i % 5 == 0 ) yield i;
  val answer = multiples.foldLeft (0) ((x,y) => x + y);
}

// Using sets
object ex1_b {
	val multiplesOf3 = 0 until 1000 by 3
	val multiplesOf5 = 0 until 1000 by 5
	//val answer = (multiplesOf3 union multiplesOf5).foldLeft (0) ((x,y) => x + y); //Range union isn't set union
	//val answer = multiplesOf3.union(multiplesOf5).foldLeft (0) ((x,y) => x + y);

	val answer = new scala.collection.immutable.HashSet().++(multiplesOf3).++(multiplesOf5).foldLeft (0) ((x,y) => x + y);
}

// Lazy list
object ex1_c {
  lazy val multiples = for (i <- Iterator.from(0) if i % 3 == 0 || i % 5 == 0 ) yield i;
	val answer = multiples.takeWhile((x) => x < 1000).foldLeft (0) ((x,y) => x + y);
}