75392e54c7
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@757 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
73 lines
1.3 KiB
Plaintext
73 lines
1.3 KiB
Plaintext
|
|
:- object(circular,
|
|
extends(salesman)).
|
|
|
|
|
|
:- info([
|
|
author is 'Paulo Moura',
|
|
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([Town| Towns], Route) :-
|
|
route(Towns, Town~Town, Route).
|
|
|
|
|
|
route([], Route, Route).
|
|
|
|
route([Town| Towns], Route, Route2) :-
|
|
best_place(Route, Town, Best),
|
|
split(Best, Route, Town, Split),
|
|
route(Towns, Split, Route2).
|
|
|
|
|
|
best_place(Route, Town, Best) :-
|
|
best_place(Route, Town, 10000000, 0, 0, Best).
|
|
|
|
best_place(R~T1~T2, Town, XD, _, I, Best) :-
|
|
atom(T1),
|
|
atom(T2),
|
|
extra(T1, Town, T2, XT),
|
|
XT < XD,
|
|
I2 is I + 1,
|
|
best_place(R~T1, Town, XT, I2, I2, Best).
|
|
|
|
best_place(R~T1~T2, Town, XD, XI, I, Best) :-
|
|
atom(T1),
|
|
atom(T2),
|
|
I2 is I + 1,
|
|
best_place(R~T1, Town, XD, XI, I2, Best).
|
|
|
|
best_place(T1~T2, Town, XD, _, I, Best) :-
|
|
atom(T1),
|
|
atom(T2),
|
|
extra(T1, Town, T2, XT),
|
|
XT < XD,
|
|
Best is I + 1.
|
|
|
|
best_place(_~_, _, _, XI, _, XI).
|
|
|
|
|
|
split(0, Route, Town, Route~Town).
|
|
|
|
split(IX, Route~Town1, Town, Split~Town1) :-
|
|
IX2 is IX - 1,
|
|
split(IX2, Route, Town, Split).
|
|
|
|
split(1, Route, Town, Town~Route).
|
|
|
|
|
|
extra(T1, T, T2, E) :-
|
|
T1::crow_flies(T, E1),
|
|
T::crow_flies(T2, E2),
|
|
T1::crow_flies(T2, E3),
|
|
E is E1 + E2 - E3.
|
|
|
|
|
|
:- end_object.
|