Intermediate Exercism • ocaml

Perfect Numbers

Challenge Overview

Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for positive integers.

Visit the perfect-numbers exercise on Exercism to read the full instructions and download the exercise files.

Community Solutions

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The following are the top 3 community solutions by stars:

Solution 1 by @gumminoppe (⭐ 0) — View on Exercism
Solution 2 by @QVvaOjB3iT (⭐ 0) — View on Exercism
Solution 3 by @hyphenrf (⭐ 0) — View on Exercism

Source: Exercism ocaml/perfect-numbers

💡 View Solution

let aliquot_sum num =
  let open Seq in
  ints 1
  |> take_while (fun p -> p * p <= num)
  |> filter (fun p -> num mod p = 0)
  |> fold_left 
      (fun sum p ->
        let q = num / p in
        sum + if p = q then p else p + q) 
      (-num)