114 lines
2.1 KiB
Perl
114 lines
2.1 KiB
Perl
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Binomial Heap imlementation based on
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%
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% Functional Binomial Queues
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% James F. King
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% University of Glasgow
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%
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% Author: Tom Schrijvers
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% Email: Tom.Schrijvers@cs.kuleuven.ac.be
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% Copyright: K.U.Leuven 2004
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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:- module(binomialheap,
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[
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empty_q/1,
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insert_q/3,
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insert_list_q/3,
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delete_min_q/3,
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find_min_q/2
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]).
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:- use_module(library(lists)).
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% data Tree a = Node a [Tree a]
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% type BinQueue a = [Maybe (Tree a)]
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% data Maybe a = Zero | One a
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% type Item = (Entry,Key)
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entry(Entry-_,Entry).
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key(_-Key,Key).
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empty_q([]).
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meld_q(P,Q,R) :-
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meld_qc(P,Q,zero,R).
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meld_qc([],Q,zero,Q) :- !.
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meld_qc([],Q,C,R) :- !,
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meld_q(Q,[C],R).
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meld_qc(P,[],C,R) :- !,
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meld_qc([],P,C,R).
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meld_qc([zero|Ps],[zero|Qs],C,R) :- !,
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R = [C | Rs],
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meld_q(Ps,Qs,Rs).
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meld_qc([one(node(X,Xs))|Ps],[one(node(Y,Ys))|Qs],C,R) :- !,
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key(X,KX),
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key(Y,KY),
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( KX < KY ->
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T = node(X,[node(Y,Ys)|Xs])
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;
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T = node(Y,[node(X,Xs)|Ys])
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),
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R = [C|Rs],
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meld_qc(Ps,Qs,one(T),Rs).
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meld_qc([P|Ps],[Q|Qs],C,Rs) :-
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meld_qc([Q|Ps],[C|Qs],P,Rs).
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insert_q(Q,I,NQ) :-
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meld_q([one(node(I,[]))],Q,NQ).
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insert_list_q([],Q,Q).
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insert_list_q([I|Is],Q,NQ) :-
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insert_q(Q,I,Q1),
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insert_list_q(Is,Q1,NQ).
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min_tree([T|Ts],MT) :-
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min_tree_acc(Ts,T,MT).
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min_tree_acc([],MT,MT).
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min_tree_acc([T|Ts],Acc,MT) :-
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least(T,Acc,NAcc),
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min_tree_acc(Ts,NAcc,MT).
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least(zero,T,T) :- !.
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least(T,zero,T) :- !.
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least(one(node(X,Xs)),one(node(Y,Ys)),T) :-
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key(X,KX),
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key(Y,KY),
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( KX < KY ->
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T = one(node(X,Xs))
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;
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T = one(node(Y,Ys))
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).
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remove_tree([],_,[]).
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remove_tree([T|Ts],I,[NT|NTs]) :-
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( T == zero ->
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NT = T
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;
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T = one(node(X,_)),
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( X == I ->
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NT = zero
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;
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NT = T
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)
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),
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remove_tree(Ts,I,NTs).
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delete_min_q(Q,NQ,Min) :-
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min_tree(Q,one(node(Min,Ts))),
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remove_tree(Q,Min,Q1),
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reverse(Ts,RTs),
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make_ones(RTs,Q2),
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meld_q(Q2,Q1,NQ).
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make_ones([],[]).
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make_ones([N|Ns],[one(N)|RQ]) :-
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make_ones(Ns,RQ).
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find_min_q(Q,I) :-
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min_tree(Q,one(node(I,_))).
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