DouKaku?

#!/usr/bin/env ruby
def f(n, m = 0)
    puts m    
    n == m ? return : f(n, m + 10 ** (m.to_s.size - 1) )
end
f(300)

(* 例解の *)
#load "nums.cma";;
open Num
let f = 
  let rec loop n m =
    let s = string_of_num m in print_endline s;
    if n<>m then loop n (m +/ (power_num (Int 10) (Int (String.length s - 1))))
  in 
    fun n -> loop (Int n) (Int 0);; 
(* f 300;; *)

(* 正規表現の *)
#load "str.cma";;
let f =
  let reg = Str.regexp "^[0-9]?0*$" in
  fun n -> Str.string_match reg (string_of_int n) 0;;
(* for i = 0 to 300 do (if f i then Printf.printf "%d\n" i) done;; *)

(* 自力の *)
let f n = 
  let rec loop next diff b = 
    if n<b then () else
    if next>b then (Printf.printf "%d\n" b; loop next diff (diff + b)) else
    loop (next*10) next b
  in loop 10 1 0;;