import collection.mutable.HashMap
trait CoderTrait {
val words: List[String]
(2 -> "ABC", new ArrowAssoc('3') -> "DEF")
private val mnemonics = Map(
'2' -> "ABC", '3' -> "DEF", '4' -> "GHI", '5' -> "JKL",
'6' -> "MNO", '7' -> "PQRS", '8' -> "TUV", '9' -> "WXYZ")
('1', "1") match {
case (digit, str) => true
case _ => false
}
/** Invert the mnemonics map to give a map from chars 'A' ... 'Z' to '2' ... '9' */
private val charCode0: Map[Char, Char] = mnemonics withFilter {
case (digit, str) => true
case _ => false
} flatMap { x$1 =>
x$1 match {
case (digit, str) => str map (ltr => ltr -> digit)
}
}
private val charCode: Map[Char, Char] =
for ((digit, str) <- mnemonics; ltr <- str) yield ltr -> digit
/** Maps a word to the digit string it can represent */
private def wordCode(word: String): String = word map charCode
/** A map from digit strings to the words that represent them */
private val wordsForNum: Map[String, List[String]] =
words groupBy wordCode withDefaultValue Nil
/** All ways to encode a number as a list of words */
def encode(number: String): Set[List[String]] =
if (number.isEmpty) Set(Nil)
else {
for {
splitPoint <- 1 to number.length
word <- wordsForNum(number take splitPoint)
rest <- encode(number drop splitPoint)
} yield word :: rest
}.toSet
/** Maps a number to a list of all word phrases that can represent it */
def translate(number: String): Set[String] = encode(number) map (_ mkString " ")
}
object Coder {
def main(args : Array[String]) : Unit = {
val coder = new CoderTrait {
val words = List("Scala", "sobls", "Python", "Ruby", "C", "A", "rocks", "sucks", "works", "Racka")
}
// println(coder.wordsForNum)
println(coder.translate("7225276257"))
}
}
