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 (4.10.0) (judge verdict: Accepted)

open Core

let n, a, b = Scanf.scanf "%d %d %d" (fun n a b -> (n, a, b))

let nums = List.range 1 (n + 1)

let rec digits i = if i <= 0 then 0 else (i mod 10) + digits (i / 10)

let s =
  nums
  |> List.map ~f:(fun n ->
         let d = digits n in
         if a <= d && d <= b then n else 0)
  |> List.fold_left ~init:0 ~f:( + )

let () = Printf.printf "%d\n" s