Hackerrank - Filter positions in a list

Problem Statement
A description of the problem can be found on Hackerrank.

Solution

object FilterPositions extends App {
  def f(arr: List[Int]): List[Int] =
    arr match {
      case x :: y :: l => y :: f(l)
      case x :: y => y
      case Nil => Nil
    }

  println(f(io.Source.stdin.getLines.toList.map(_.trim).map(_.toInt)).mkString("\n"))
}

object FilterPositions extends App {

def f(arr: List[Int]): List[Int] =

arr match {

case x :: y :: l => y :: f(l)

case x :: y => y

case Nil => Nil

}

println(f(io.Source.stdin.getLines.toList.map(_.trim).map(_.toInt)).mkString("\n"))

}

Solution also available on my GitHub.

Pavol Pidanič

I can count to 1023 with 10 fingers

Hackerrank – Filter positions in a list