62 lines
1.9 KiB
OCaml
62 lines
1.9 KiB
OCaml
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(* Copyright (C) 2014--2016 Petter A. Urkedal <paurkedal@gmail.com>
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*
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* This library is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or (at your
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* option) any later version, with the LGPL-3.0 Linking Exception.
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*
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* This library is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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* License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* and the LGPL-3.0 Linking Exception along with this library. If not, see
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* <http://www.gnu.org/licenses/> and <https://spdx.org>, respectively.
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*)
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module type S = sig
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type elt
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type t
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val empty : t
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val is_empty : t -> bool
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val card : t -> int
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val push : elt -> t -> t
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val merge : t -> t -> t
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val pop_e : t -> elt * t
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end
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module Make (Elt : Set.OrderedType) = struct
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type elt = Elt.t
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type t = O | Y of int * elt * t * t
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let empty = O
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let is_empty h = h = O
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let card = function
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| O -> 0
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| Y (n, _, _, _) -> n
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let rec push e' = function
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| O -> Y (1, e', O, O)
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| Y (n, e, hL, hR) ->
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let e_min, e_max = if Elt.compare e' e < 0 then e', e else e, e' in
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if card hL < card hR then Y (n + 1, e_min, push e_max hL, hR)
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else Y (n + 1, e_min, hL, push e_max hR)
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let rec merge hL hR =
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match hL, hR with
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| O, h | h, O -> h
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| Y (nL, eL, hA, hB), Y (nR, eR, hC, hD) ->
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if Elt.compare eL eR < 0 then Y (nL + nR, eL, merge hA hB, hR)
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else Y (nL + nR, eR, hL, merge hC hD)
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let pop_e = function
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| O -> invalid_arg "Caqti_heap.pop_e: Empty heap."
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| Y (_, e, hL, hR) -> e, merge hL hR
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end
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