//zadanie 1
//def exists[A](xs:List[A])(p:A=>Boolean):Boolean=
//xs match {
//  case h::t => if(p(h)) true else exists(t)(p)
//  case Nil => false
//}
//
//exists (List(5,1,2,3)) (_ == 2)  ==   true
//exists (List(5,1,2,3)) (_ == 6)  ==   false
//exists (List()) (_ == 6)  ==   false
//
//def existsFL[A](xs:List[A])(p:A=>Boolean):Boolean=
//  (xs foldLeft false)((x:Boolean,y:A)=> x || p(y))
//
//existsFL (List(5,1,2,3)) (_ == 2)  ==   true
//existsFL (List(5,1,2,3)) (_ == 6)  ==   false
//existsFL (List()) (_ == 6)  ==   false
//
//def existsFR[A](xs:List[A])(p:A=>Boolean):Boolean=
//  (xs foldRight false)((x:A, y:Boolean)=> y || p(x))
//
//existsFR (List(5,1,2,3)) (_ == 2)  ==   true
//existsFR (List(5,1,2,3)) (_ == 6)  ==   false
//existsFR (List()) (_ == 6)  ==   false
//
//zadanie2
//def filter[A](xs:List[A])(p:A=>Boolean):List[A]=
//  (xs foldRight List[A]()) ((x:A, y:List[A]) => if(p(x)) x::y else y)
//
//filter (List(2,7,1,3,7,8,4,1,6,9)) (_ > 3) == List(7, 7, 8, 4, 6, 9)
//filter (List(0)) (_ > 3) == List()
//
//zadanie3
//def remove1[A](xs:List[A])(p:A=>Boolean):List[A]=
//  xs match {
//    case h::t => if(p(h)) t else h::remove1(t)(p)
//    case _ => Nil
//}
//
//remove1(List(1,2,3,2,5)) (_ == 2) == List(1, 3, 2, 5)
//remove1(List(1,2,3,2,5)) (_ == 6) == List(1,2,3,2,5)
//remove1(List()) (_ == 6) == List()
//
//
//zadanie4
//def splitAt[A](xs:List[A])(n:Int):(List[A],List[A])= {
//  def splitAtAcc(xs: List[A])(acc1: List[A], acc2: List[A])(n: Int)
//  : (List[A], List[A]) =
//    xs match {
//      case h :: t if n > 0 => splitAtAcc(t)(h::acc1, acc2)(n-1)
//      case _ => (acc1.reverse, xs)
//    }
//  splitAtAcc(xs)(List(), List())(n)
//}
//
//splitAt (List('a','b','c','d','e')) (2)
//splitAt (List('a','b','c','d','e')) (2) == (List('a', 'b'), List('c', 'd', 'e'))