2001-06-06 20:07:01 +00:00
|
|
|
|
|
|
|
|
:- object(permute,
|
|
|
|
|
extends(salesman)).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
:- info([
|
2003-02-05 00:15:28 +00:00
|
|
|
author is 'Paulo Moura',
|
2001-06-06 20:07:01 +00:00
|
|
|
version is 1.0,
|
|
|
|
|
date is 2000/4/22,
|
|
|
|
|
comment is '.',
|
|
|
|
|
source is 'Example adopted from the Francis G. McCabe L&O documentation.']).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
:- op(400, yfx, ~).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
route(Towns, Route) :-
|
|
|
|
|
findall(
|
|
|
|
|
(Towns2, Length),
|
|
|
|
|
(permute(Towns, Towns2), route_length(Towns2, Length)),
|
|
|
|
|
List),
|
|
|
|
|
shortest(List, Route).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
permute([Town], Town).
|
|
|
|
|
|
|
|
|
|
permute(Towns, Towns2~Town) :-
|
|
|
|
|
delete(Towns, Town, Towns3),
|
|
|
|
|
permute(Towns3, Towns2).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
delete([Head| Tail], Head, Tail).
|
|
|
|
|
|
|
|
|
|
delete([Head| Tail], Element, [Head| Tail2]):-
|
|
|
|
|
delete(Tail, Element, Tail2).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
route_length(Town, 0) :-
|
|
|
|
|
atom(Town), !.
|
|
|
|
|
|
|
|
|
|
route_length(Towns~Town1~Town2, Length) :-
|
|
|
|
|
!,
|
|
|
|
|
route_length(Towns~Town1, Length1),
|
|
|
|
|
Town1::crow_flies(Town2, Length2),
|
|
|
|
|
Length is Length1 + Length2.
|
|
|
|
|
|
|
|
|
|
route_length(Town1~Town2, Length) :-
|
|
|
|
|
Town1::crow_flies(Town2, Length).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
shortest(List, Shortest) :-
|
|
|
|
|
shortest(List, null, 1000000, Shortest).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
shortest([], Route, Length, (Route, Length)).
|
|
|
|
|
|
|
|
|
|
shortest([(Route, Length)| Routes], _, LX, Shortest) :-
|
|
|
|
|
Length < LX, !,
|
|
|
|
|
shortest(Routes, Route, Length, Shortest).
|
|
|
|
|
|
|
|
|
|
shortest([_| Routes], RX, LX, Shortest) :-
|
|
|
|
|
shortest(Routes, RX, LX, Shortest).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
:- end_object.
|
