Solves reddit challenge 220

SentenceMangle.scala

package tlo.reddit

object SentenceMangle {
  val sampleInputs = Seq(
    "This challenge doesn't seem so hard.",
    "There are more things between heaven and earth, Horatio, than are dreamt of in your philosophy."
  )

  val challengeInputs = Seq(
    "Eye of Newt, and Toe of Frog, Wool of Bat, and Tongue of Dog.",
    "Adder's fork, and Blind-worm's sting, Lizard's leg, and Howlet's wing.",
    "For a charm of powerful trouble, like a hell-broth boil and bubble."
  )

  def main(args: Array[String]) {
    sampleInputs.zipWithIndex.foreach { case (sentence, index) =>
      println(s"==== Sentence $index ====")
      println(s"Input: ${sentence + 1}")
      println(s"Output: ${mangle(sentence)}")
      println("")
    }
  }

  def mangle(original: String): String = {
    original.split(' ')
      .map(sortWord)
      .mkString(" ")
  }

  def sortWord(word: String): String = {
    val sortedLetters = word.toLowerCase.filter(_.isLetter).sorted.toList
    val startingState = (sortedLetters, "")

    // Uses a poor man's Iteratee to do the sort. If a letter, we pop a letter off the front of sorted letter list, and
    // append it to the word accumulator. The next state is the remainder of the sorted letters, and the accumulated
    // sentence so far.
    val newWord = word.foldLeft(startingState) {
      case ((letters, acc), thisChar) =>
        thisChar.isLetter match {
          case true => (letters.tail, acc + letters.head)
          case false => (letters, acc + thisChar)
        }
    }._2

    if (word(0).isUpper) newWord.capitalize else newWord
  }
}