Natural weekday chooser

weeker.scala

val weekdays = IndexedSeq("Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat")
 
def solve(idx: Int*) = (idx foldLeft Seq.empty[(Int, Int)]) {
  case (ts :+ ((start, end)), x) if x == end + 1 => ts :+ (start, x)
  case (t, x) => t :+ (x, x)
} map {
  case (start, end) if start == end => weekdays(start)
  case (start, end) => s"${weekdays(start)}-${weekdays(end)}"  
}
 
println(solve(1, 2, 3, 5))
println(solve(1, 2, 5))
println(solve(2, 3, 4))
println(solve(1, 3, 5))
println(solve(0, 1, 3, 5, 6))