48 lines
1.1 KiB
OCaml
48 lines
1.1 KiB
OCaml
|
(* Naive persistent implementation of Union/Find: O(n^2) worst case *)
|
||
|
|
|
||
|
|
module Make (Item: Partition.Item) =
|
||
|
|
struct
|
||
|
|
|
||
|
|
type item = Item.t
|
||
|
|
type repr = item (** Class representatives *)
|
||
|
|
|
||
|
|
let equal i j = Item.compare i j = 0
|
||
|
|
|
||
|
|
module ItemMap = Map.Make (Item)
|
||
|
|
|
||
|
|
type height = int
|
||
|
|
|
||
|
|
type partition = item ItemMap.t
|
||
|
|
type t = partition
|
||
|
|
|
||
|
|
let empty = ItemMap.empty
|
||
|
|
|
||
|
|
let rec repr item partition =
|
||
|
|
let parent = ItemMap.find item partition in
|
||
|
|
if equal parent item
|
||
|
|
then item
|
||
|
|
else repr parent partition
|
||
|
|
|
||
|
|
let is_equiv (i: item) (j: item) (p: partition) =
|
||
|
|
equal (repr i p) (repr j p)
|
||
|
|
|
||
|
|
let get_or_set (i: item) (p: partition) : item * partition =
|
||
|
|
try repr i p, p with Not_found -> i, ItemMap.add i i p
|
||
|
|
|
||
|
|
let equiv (i: item) (j :item) (p: partition) : partition =
|
||
|
|
let ri, p = get_or_set i p in
|
||
|
|
let rj, p = get_or_set j p in
|
||
|
|
if equal ri rj then p else ItemMap.add ri rj p
|
||
|
|
|
||
|
|
let alias = equiv
|
||
|
|
|
||
|
|
(* Printing *)
|
||
|
|
|
||
|
|
let print p =
|
||
|
|
let print src dst =
|
||
|
|
Printf.printf "%s -> %s\n"
|
||
|
|
(Item.to_string src) (Item.to_string dst)
|
||
|
|
in ItemMap.iter print p
|
||
|
|
|
||
|
|
end
|