Submission #1966313

---

Source Code Expand

let rec seed acc x d = function
  | 0 -> acc
  | n -> seed ((x, d) :: acc) (8 * x + 2 * d) (d * 10) (n - 1)
let seed = seed [] 0 1

let rec solve n = function
  | [] -> 0
  | (seed, d) :: rest ->
      if n / d <= 0 then solve (n mod d) rest
      else if n / d <= 3 then n / d * seed + solve (n mod d) rest
      else if n / d <= 4 then 1 + n mod d + solve (4 * d - 1) ((seed, d) :: rest)
      else if n / d <= 8 then (n / d - 1) * seed + d + solve (n mod d) rest
      else 1 + n mod d + solve (9 * d - 1) ((seed, d) :: rest)
let solve n = solve n (seed 19)

let () = Scanf.scanf "%d %d" (fun n m -> Printf.printf "%d\n" (solve m - solve (n - 1)))

Submission Info

Judge Result