package ninetyNineScalaProblems.lists

import scala.annotation.tailrec

object Problem14:
    def duplicateElements(list: List[Any]): List[Any] =
        @tailrec
        def loop(cursor: List[Any], acc: List[Any]): List[Any] =
            cursor match
                case e :: tail =>
                    loop(tail, e :: e :: acc)
                case Nil =>
                    acc

        loop(list, List()).reverse

    def duplicateElements2(list: List[Any]): List[Any] =
        list.flatMap(i => i :: List(i))