A simple word decoder for "7 days to end with you"

7-days-to-end-with-you-word-decoder.scala

val NUM_LETTERS = 25

implicit class RichChar(c: Char) {
  def shiftLetter(i: Int): Char = {
    if (c.isLetter) {
      val (a, z) = if (c.isLower) ('a', 'z') else ('A', 'Z')
      val n = i % NUM_LETTERS
      (((c + n) % z % a) + a).toChar
    } else {
      c
    }
  }
}

def words(s: String): Seq[String] = {
  for (i <- 0 until NUM_LETTERS) yield s.map(_.shiftLetter(i))
}

words("orqhoc") // Vector(orqhoc, psripd, qtsjqe, rutkrf, svulsg, twvmth, uxwnui, vyxovj, waypwk, xbaqxl, ycbrym, adcsan, bedtbo, cfeucp, dgfvdq, ehgwer, fihxfs, gjiygt, hkjahu, ilkbiv, jmlcjw, knmdkx, lonely, mpofma, nqpgnb)