有人可以在2011年Scala Days上的Odersky主题演讲中分享干净版的C

$scala CoderTest 7225276257 let us see if scala rocks is in the output
Set(scala rocks)

此输出表示对于给出的电话号码和字典,找到的唯一编码是“scala rocks”这对单词.

这是测试驱动程序：

object CoderTest extends App {
  val digits::words = args.toList
  println( new Coder(words) translate digits )
}

这是Coder类本身.我已经更改了一些标识符和注释,以使它们更清晰.

class Coder( words: List[String] ) {

  // In this code "num" means a string of digits,e.g. "834921".

  val digitToLetters = Map(
    '2' -> "ABC",'3' -> "DEF",'4' -> "GHI",'5' -> "JKL",'6' -> "MNO",'7' -> "PQRS",'8' -> "TUV",'9' -> "WXYZ"
  )

  // Invert digitToLetters to give a map from chars 'A'..'Z' to '2'..'9'.
  val letterToDigit =
    for ( (digit,itsLetters) <- digitToLetters; letter <- itsLetters )
      yield ( letter -> digit ) 

  // Maps a word to the digit string it can represent.
  def wordToNum( word: String ) = word.toUpperCase map letterToDigit 

  // Map from digit string to words in our dictionary that represent it.
  // e.g. 5282 -> List( Java,Kata,Lava,... )
  val numToWords = ( words groupBy wordToNum ) withDefaultValue List()

  // Maps a digit string to all phrases (lists of dictionary words)
  // that represent it.
  def numToPhrases( num: String ): Set[ List[String] ] =
    if ( num.isEmpty )
      Set( List() )
    else (
      for { splitPoint <- 1 to num.length
            word   <- numToWords  ( num take splitPoint )
            phrase <- numToPhrases( num drop splitPoint )
      } yield word::phrase
    ).toSet

  // Maps a number to the set of all word phrases that can represent it.
  def translate( num: String ) = numToPhrases(num) map ( _ mkString " " ) 

}

但请记住,指定构成公共API一部分的方法的返回类型实际上是个好主意.现在你可以使用splitAt一次性完成一次拍摄.