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Determine if a string has all unique characters: Difference between revisions
Determine if a string has all unique characters (view source)
Revision as of 15:55, 6 July 2022
, 1 year agoAdd OCaml
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The string contains duplicate characters.
Character 🐡 (1f421) is present at positions 3 and 8.</pre>
=={{header|OCaml}}==
Using a map to store characters we've met (as keys) and their first position (as indexes).
<lang ocaml>module CMap = Map.Make(struct
type t = char
let compare = compare
end)
(** Add index as argument to string.fold_left *)
let string_fold_left_i f acc str =
snd (String.fold_left
(fun (index, acc) char -> (index+1, f acc index char))
(0, acc) str)
exception Found of int * int * char
let has_duplicates str =
try let _ = string_fold_left_i
(fun map index char ->
match CMap.find_opt char map with
| None -> CMap.add char index map
| Some i -> raise (Found (i,index,char)))
CMap.empty str
in Ok ()
with Found (i,j,c) -> Error (i,j,c)
let printer str =
Format.printf "%S (len %d) : " str (String.length str);
match has_duplicates str with
| Ok () -> Format.printf "No duplicates.\n"
| Error (i,j,c) -> Format.printf "Duplicate '%c' (%#x) at %d and %d\n" c (int_of_char c) i j
let () =
printer "";
printer ".";
printer "abcABC";
printer "XYZ ZYX";
printer "1234567890ABCDEFGHIJKLMN0PQRSTUVWXYZ"</lang>
{{out}}
<pre>"" (len 0) : No duplicates.
"." (len 1) : No duplicates.
"abcABC" (len 6) : No duplicates.
"XYZ ZYX" (len 7) : Duplicate 'Z' (0x5a) at 2 and 4
"1234567890ABCDEFGHIJKLMN0PQRSTUVWXYZ" (len 36) : Duplicate '0' (0x30) at 9 and 24</pre>
=={{header|Perl}}==
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