Duplicate Character Counter in OCaml

Duplicate Character

Counter in OCaml

Welcome to the Duplicate Character Counter in OCaml page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

module CharMap = Map.Make (Char)

let increment_map (counts, seen) k =
  match CharMap.find_opt k counts with
  | Some n -> (CharMap.add k (n + 1) counts, seen)
  | None -> (CharMap.add k 1 counts, k :: seen)

let count_chars str =
  str |> String.to_seq |> Seq.fold_left increment_map (CharMap.empty, [])

let dupes str =
  let counts, seen = count_chars str in
  seen |> List.rev
  |> List.filter_map (fun c ->
      let count = CharMap.find c counts in
      if count > 1 then Some (c, count) else None)

let print_dupes str =
  match dupes str with
  | [] -> print_endline "No duplicate characters"
  | counts ->
      List.iter (fun (c, count) -> Printf.printf "%c: %d\n" c count) counts

let get_arg argv =
  match argv with [| _; "" |] -> None | [| _; str |] -> Some str | _ -> None

let () =
  match get_arg Sys.argv with
  | Some str -> print_dupes str
  | None -> print_endline "Usage: please provide a string"

Duplicate Character Counter in OCaml was written by:

• alope107

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

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