Problem:
Score : 200 points

Problem Statement

Find the sum of the integers between 1 and N (inclusive), whose sum of digits written in base 10 is between A and B (inclusive).

Constraints

1 \leq N \leq 10^4

1 \leq A \leq B \leq 36

All input values are integers.

Input

Input is given from Standard Input in the following format:

N A B

Output

Print the sum of the integers between 1 and N (inclusive), whose sum of digits written in base 10 is between A and B (inclusive).

Sample Input 1

20 2 5

Sample Output 1

84

Among the integers not greater than 20, the ones whose sums of digits are between 2 and 5, are: 2,3,4,5,11,12,13,14 and 20. We should print the sum of these, 84.

Sample Input 2

10 1 2

Sample Output 2

13

Sample Input 3

100 4 16

Sample Output 3

4554

Solution in OCaml (4.02.3) (judge verdict: Accepted)

let get_3_ints () = Scanf.scanf "%d %d %d" (fun u v w -> u,v,w)
let range ?(stride=1) u v =
  let rec f0 i a = if i>v then a else f0 (i+stride) (i::a)
  in f0 u []
let digits v =
  let rec f0 p a = if p=0 then a else f0 (p/10) ((p mod 10)::a)
  in f0 v []

let () =
  let (n,a,b) = get_3_ints ()
  in range 1 n
  |> List.fold_left (fun u v ->
    let k = v |> digits |> List.fold_left (+) 0
    in if a<=k&&k<=b then u+v else u
  ) 0
  |> Printf.printf "%d\n"