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FirstLab.scala

package FirstLab

object Application{
  def main(args: Array[String]):Unit={
    println("List:");
    val list = List(1,2,3,4,5,6,7,8,9,10);
    printList(list);
    println();
    println("Recursive func:")
    printList(recursive(list))
    println();
    println("Tail recursive func:")
    printList(tailRecursive(list));
  }


  def recursive(list: List[Int]): List[Int]={
     if(list==Nil) return Nil;
     return list.head :: list.head :: recursive(list.tail);
  }

  def tailRecursive(list: List[Int]): List[Int] ={
    def iter(x: List[Int], result:List[Int]):List[Int]={
      if(x==Nil) result;
      else iter(x.tail, x.head::x.head::result);
    }

    iter(list, Nil).reverse;
  }

  def printList(list: List[Int]): Unit ={
    if(list==Nil) return;
    print(list.head);
    print(" ");
    printList(list.tail);
  }
}