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 rec seq a b = if a > b then [] else a :: seq (a+1) b
let rec dig_sum x = if x = 0 then 0 else x mod 10 + dig_sum (x / 10)
let () =
  Scanf.scanf "%d %d %d" @@ fun n a b ->
    seq 1 n
    |> List.fold_left (fun s x ->
        let d = dig_sum x in
        if a <= d && d <= b then s+x else s) 0
    |> Printf.printf "%d\n"