This commit is contained in:
Simon Cruanes 2019-11-29 14:44:01 -06:00
parent 0266a39b04
commit 99fed971d6

View file

@ -124,13 +124,18 @@ module Make(Elt : RANKED) = struct
*) *)
let remove_min ({heap} as s) = let remove_min ({heap} as s) =
if Vec.size heap=0 then raise Not_found; match Vec.size heap with
let x = Vec.get heap 0 in | 0 -> raise Not_found
let new_hd = Vec.pop heap in (* new head *) | 1 ->
Vec.set heap 0 new_hd; let x = Vec.pop heap in
Elt.set_idx new_hd 0;
(* remove [x]. do it after [new_hd.idx<-0] in case [x==new_hd] *)
Elt.set_idx x _absent_index; Elt.set_idx x _absent_index;
x
| _ ->
let x = Vec.get heap 0 in
let new_hd = Vec.pop heap in (* heap.last() *)
Vec.set heap 0 new_hd;
Elt.set_idx x _absent_index;
Elt.set_idx new_hd 0;
(* enforce heap property again *) (* enforce heap property again *)
if Vec.size heap > 1 then ( if Vec.size heap > 1 then (
percolate_down s new_hd; percolate_down s new_hd;