jacekkolodziejski

def length[T](ts: Seq[T]): Int = (0 /: ts)((x, _) => x + 1)

jacekkolodziejski

  import annotation.tailrec
  def encode[T](ts: Seq[T]): Seq[(Int, T)] = {
    @tailrec
    def go(acc: Seq[(Int, T)], ts: Seq[T]): Seq[(Int, T)] = ts match {
      case Nil => acc
      case _ => {
        val (left, right) = ts.span(_ == ts.head)
        go(acc :+ (left.size, left.head), right)
      }
    }

jacekkolodziejski

  def isSorted[A](as: Array[A])(gt: (A, A) => Boolean): Boolean = as.size match {
    case 0 => true
    case 1 => true
    case _ =>
      val (h2, tail) = as.splitAt(2)
      gt(h2(0), h2(1)) && isSorted(tail)(gt)
  }

jacekkolodziejski

package pl.japila.scalania.s99

object S99_P20 {
  def removeAt[T](n: Int, ts: Seq[T]): (Seq[T], T) =
    (ts.take(n) ++ ts.drop(n + 1), ts(n))
}

jacekkolodziejski

object S99_P19 {
  def rotate[T](n: Int, ts: Seq[T]): Seq[T] = {
    val ammount = if (n > 0) n else (n + ts.length)
    ts.drop(ammount) ++ ts.take(ammount)
  }
}

jacekkolodziejski

object S99_P18 {
  import S99_P17.split
  def slice[T](from: Int, to: Int, ts: Seq[T]): Seq[T] =
    split(ts.length - to, split(from, ts)._2.reverse)._2.reverse

}

jacekkolodziejski

import annotation.tailrec

object S99_P17 {
  def split[T](n: Int, ts: Seq[T]): (Seq[T], Seq[T]) =
    ts.splitAt(n)

  def split[T](n: Int, ts: Seq[T]): (Seq[T], Seq[T]) =
    (ts.take(n), ts.drop(n))

  def split[T](n: Int, ts: Seq[T]): (Seq[T], Seq[T]) = {

jacekkolodziejski

object S99_P16 {
  def drop[T](n: Int, ts: Seq[T]): Seq[T] = {
    var iter = 0;
    def op(el: T): Boolean = { iter = iter + 1; (iter % n != 0) }
    ts filter op
  }

  def drop[T](n: Int, ts: Seq[T]): Seq[T] = 
    for (e <- ts.zipWithIndex if (e._2 + 1) % n != 0) yield e._1

jacekkolodziejski

object S99_P15 {
  def duplicateN[T](n: Int, ts: Seq[T]): Seq[T] =
    ts flatMap { List.fill(n)(_) }

  
  def duplicateN[T](n: Int, ts: Seq[T]): Seq[T] = ts match{
  	case Nil => Nil
  	case head::tail => List.fill(n)(head) ++ duplicateN(n,tail)
  }  

jacekkolodziejski

object S99_P14 {
  def duplicate[T](ts: Seq[T]): Seq[T] = ts.flatMap(e => List(e, e))
}