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scalasequencelist-comprehensionfibonacci

Generate a sequence of Fibonacci number in Scala


  def fibSeq(n: Int): List[Int] = {
    var ret = scala.collection.mutable.ListBuffer[Int](1, 2)
    while (ret(ret.length - 1) < n) {
      val temp = ret(ret.length - 1) + ret(ret.length - 2)
      if (temp >= n) {
        return ret.toList
      }
      ret += temp
    }
    ret.toList
  }

So the above is my code to generate a Fibonacci sequence using Scala to a value n. I am wondering if there is a more elegant way to do this in Scala?

Solution

  • There are many ways to define the Fibonacci sequence, but my favorite is this one:

    val fibs:Stream[Int] = 0 #:: 1 #:: (fibs zip fibs.tail).map{ t => t._1 + t._2 }

    This creates a stream that is evaluated lazily when you want a specific Fibonacci number.

    EDIT: First, as Luigi Plinge pointed out, the "lazy" at the beginning was unnecessary. Second, go look at his answer, he pretty much did the same thing only more elegantly.