InverseFizzbuzz : http://www.jasq.org/2/post/2012/05/inverse-fizzbuzz.html

InverseFizzbuzz.scala

// Inversefizzbuzz
//  http://www.jasq.org/2/post/2012/05/inverse-fizzbuzz.html
//
object InverseFizzbuzz extends App {

  type E = (String,Int)
  def zzubzzif(pattern:Seq[String]) = {
    val fizzbuzz = (n:Int) => (n%3, n%5) match{
      case (0,0) => ("fizzbuzz", n)
      case (0,_) => ("fizz", n)
      case (_,0) => ("buzz", n)
      case _     => ("", n)
     }

    def startsWith(stream:Stream[E]) = {
      pattern.foldLeft(Option(Seq.empty[Int], stream)){(opt,p) =>
        opt.flatMap{ case (rv,st) =>
          val head #:: tail = st
          val (f,n) =  head
          if(f == p) Some(rv :+ n, tail) else None
        }
      }
    }

    def seak(st:Stream[E]):Seq[Int] = startsWith(st) match {
      case Some((rv,st)) => rv
      case None          => seak(st.tail)
    }

    val nums = Stream.from(1).map(fizzbuzz).filterNot{case (s,_) => s.isEmpty }
    val rv = seak(nums)
    (rv.head to rv.last).toList
  }


  def _p(s:Seq[String]) = {
    println("pattern : %s" format (s.map{s => s.mkString("'", "", "'")}))
    println(zzubzzif(s))
    println("")
  }

  _p(Seq("fizz"))
  _p(Seq("buzz"))
  _p(Seq("fizz","buzz"))
  _p(Seq("fizz","buzz"))
  _p(Seq("buzz","fizz"))
  _p(Seq("fizz","buzz","fizz"))
  _p(Seq("fizz","fizz"))
  _p(Seq("fizz","fizz","buzz"))


  // Result:
  //
  // pattern : List('fizz')
  // List(3)
  //
  // pattern : List('buzz')
  // List(5)
  //
  // pattern : List('fizz', 'buzz')
  // List(3, 4, 5)
  //
  // pattern : List('fizz', 'buzz')
  // List(9, 10)
  //
  // pattern : List('buzz', 'fizz')
  // List(5, 6)
  //
  // pattern : List('fizz', 'buzz', 'fizz')
  // List(3, 4, 5, 6)
  //
  // pattern : List('fizz', 'fizz')
  // List(6, 7, 8, 9)
  //
  // pattern : List('fizz', 'fizz', 'buzz')
  // List(6, 7, 8, 9, 10)
}