map_reduce.ml

(* val map_reduce : int list -> int list list = <fun> *)
let map_reduce lst =
  let rec partition acc = function
    | 0 -> acc
    | x -> partition ((x mod 10) :: acc) (x / 10)
  in let rec map acc = function
    | [] -> List.rev acc
    | h :: tl ->
        if h > 10 then map ((partition [] h) :: acc) tl
        else map ((h :: [] ) :: acc) tl
  in map [] lst