This is great! Inspired me to make a little script in spark-shell:
> val words = oxforddict.
filter{case s => s.exists(_.isLetter) && s.forall(Character.isUpperCase(_))}.
distinct.
map((_.toLowerCase,1))
> def lcp(a:String,b:String) = { a.zip(b).takeWhile(Function.tupled(_ == _)).map(_._1).mkString }
> implicit val wordOrdering = new Ordering[String] {
> override def compare(a:String, b:String) = { val lcpIdx = lcp(a,b).length; a.substring(lcpIdx).compareTo(b.substring(lcpIdx)) }
> }
> def nextGuess(lower:String,upper:String,g:Int) = { val candidates = words.filterByRange(lower,upper).map(_._1).collect.sorted(wordOrdering).toList; val mid = candidates.length / 2; candidates.slice(mid-g/2,mid+g/2+1) }
nextGuess: (lower: String, upper: String, g: Int)
> nextGuess("prejudice","promise",1)
res42: List[String] = List(primeness)
> nextGuess("prime","promise",10)
res47: List[String] = List(procris, procrustean, procrusteanize, procrustes, procrustesian, proctitis, proctocele, proctodaeum, proctor, proctorage, proctorial)
> nextGuess("proctor","promise",10)
res48: List[String] = List(profulgent, profundity, profuse, profusely, profuseness, profusion, profusive, prog, progenerate, progeneration, progenitor)
> nextGuess("profuse","promise",12)
ding ding!!