Contents

import scala.util.Random

case class Cipher(keyOpt: Option[String]) {
  require(keyOpt.isEmpty || keyOpt.get.matches("^[a-z]+$"))

  private val alphabet = ('a' to 'z').toVector
  private lazy val randomKey = Seq.fill(26)((Random.nextInt(25) + 'a').toChar).mkString

  val key = keyOpt.getOrElse(randomKey)

  def encode(s: String): String =
    (for (i <- 0 until s.length) yield encodeChar(s, i)).mkString

  private def encodeChar(plainText: String, index: Int) = {
    var alphaIdx = alphabet.indexOf(plainText(index)) + alphabet.indexOf(key(index))

    if (alphaIdx >= alphabet.length) alphaIdx -= alphabet.length

    alphabet(alphaIdx)
  }

  def decode(s: String): String =
    (for (i <- 0 until s.length) yield decodeChar(s, i)).mkString

  private def decodeChar(cipherText: String, index: Int) = {
    var alphaIdx = alphabet.indexOf(cipherText(index)) - alphabet.indexOf(key(index))

    if (alphaIdx < 0) alphaIdx += alphabet.length

    alphabet(alphaIdx)
  }
}

Version data entries

396 entries across 396 versions & 1 rubygems

Version	Path
trackler-2.2.1.159	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.158	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.157	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.156	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.155	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.154	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.153	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.152	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.151	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.150	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.149	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.148	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.147	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.146	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.145	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.144	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.143	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.142	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.141	tracks/scala/exercises/simple-cipher/example.scala
trackler-2.2.1.140	tracks/scala/exercises/simple-cipher/example.scala