Scala training

binarySearch.scala

  def binarySearch(number: Int, numbers: List[Int]): Try[Int] = {
    import scala.annotation.tailrec
    @tailrec
    def recursive(number: Int, numbers: List[Int], left:Int = 0): Try[Int] =  {
      (numbers.length / 2) match {
        case i if (numbers == Nil) || (numbers.length == 1 && numbers(i) != number) => Failure(new NoSuchElementException)
        case i => numbers(i) match {
          case n if n == number => Try{i + left}
          case n if n > number  => recursive(number, numbers.take(i), left)
          case n if n < number  => recursive(number, numbers.drop(i), left + i)
        }
      }
    }
    recursive(number, numbers, 0)
  }

countFruitsFromLines.scala

  def countFruitsFromLines(lines: List[String]): Map[String, Int] = {
    lines.flatMap(_.split(" ")).foldLeft(Map.empty[String, Int]) { (m, w) =>
      m.updated(w, m.getOrElse(w, 0) + 1)
    }
  }

fact.scala

  def fact(n: Int): Long = {
    Range(1, math.max(n + 1, 2)).reduceLeft(_ * _)
  }

fact.stream.scala

  def fact(n: Int): Long = {
    def from(a: Long, b :Long): Stream[Long] = {
      Stream.cons(b, from(a + 1, a * b))
    }
    from(1, 1).take(n + 1).last
  }

fib.scala

  def fib(n: Long): Long = {
    def from(a: Long, b :Long): Stream[Long] = {
      Stream.cons(a, from(b, a + b))
    }
    from(0, 1).take(n.toInt + 1).last
  }

sum.scala

  def getSum(numbers: List[Int]): Long = {
    numbers.reduceLeft(_ + _)
  }