wordwheel-solver.sc

import scala.collection.mutable

// The word wheel data
val required = List[Char]('a')
val otherChars = List[Char]('t', 'n', 'd', 'o', 'e', 'c', 'i', 'u')
// Load a word list and remove anything smaller than 2 letters
val wordList = scala.io.Source.fromInputStream(getClass.getResourceAsStream("/wordsEn.txt"))
  .getLines()
  .filter(_.length > 2)

/**
  * @param word The word to order
  * @return An ordered string of the input words characters
  */
def sortWord(word: String) = word.toCharArray.sorted.mkString
// Define a hash map for storing ordered word strings to the original words
val toWords = mutable.HashMap[String, List[String]]()
// Take each word and map it to it's ordered counterpart
wordList.foreach(word => {
  val ordered = sortWord(word)
  if (toWords.contains(ordered)) {
    toWords.put(ordered, toWords.get(ordered).get :+ word)
  } else {
    toWords.put(ordered, List[String](word))
  }
})

// Generate all possible combinations of otherChars + the required characters
val allPossibles = Range(2, otherChars.length)
  .flatMap(i => otherChars.combinations(i))
  .sortWith((left, right) => left.length > right.length)
  .map(l => l.++(required))
  .map( s => sortWord(s.mkString))
  .iterator

// Get a flat list of the results
val results: Iterator[String] = allPossibles.flatMap(possible => {
  toWords.get(possible)
}).flatten
// Print the results
results.toSeq.sortWith((left, right) => {
  left.length > right.length
}).foreach(println)

Didn't realize there was a List.combinations method in Scala; could probably solve the issue with not supporting multiple characters using it.