Given an integer n, return true if it's a perfect square AND when reversed, is still a perfect square.

reversed_squares.ml

open Base
open Stdlib

let reversed_squares num =
  let perfect_root n =
    let n = float_of_int n in
    let root = Float.sqrt n in
    if root |> int_of_float |> float_of_int = root then Some root else None
  in

  let int_reverse n =
    let rec reverser rem acc =
      match n = n % rem with
      | true ->
          (n % rem / (rem / 10)) :: acc
          |> List.rev
          |> List.fold_left (fun acc dig -> (acc * 10) + dig) 0
      | false -> reverser (rem * 10) ((n % rem / (rem / 10)) :: acc)
    in
    reverser 10 []
  in

  let rev_num = int_reverse num in

  match (perfect_root num, perfect_root rev_num) with
  | Some _, Some _ -> true
  | _ -> false

let%test_module "reversed squares" =
  (module struct
    let%test_unit "test 1" = [%test_eq: bool] (reversed_squares 9) true
    let%test_unit "test 2" = [%test_eq: bool] (reversed_squares 441) true
    let%test_unit "test 3" = [%test_eq: bool] (reversed_squares 25) false
  end)