A work title: known to Beijing, Shanghai, Guangzhou, Kunming and Xi ' an five city route map. To achieve: 1) find the shortest route from Beijing to Kunming. 2) to find Beijing to Kunming, must approach the path of Shanghai. 3) find Beijing to Kunming, must approach Shanghai, but can not go to the path of Guangzhou.
|
Beijing |
Shanghai |
Guangzhou |
Kunming |
Xian |
Beijing |
|
|
|
|
|
Shanghai |
1462 |
|
|
|
|
Guangzhou |
2107 |
1811 |
|
|
|
| Kunming |
3179 |
2677 |
2216 |
|
|
| Xian |
1165 |
1511 |
2129 |
1942 |
|
Visual Prolog source program: Domains
City=symbol
citylist=city*
Distance=integer
Predicates
Nondeterm Road (City,city,distance)
Nondeterm Connected (city,city,distance)
Nondeterm Route (city,city,citylist,citylist,distance)
Member (City,citylist)
Showallroutes (city,city)
Shorterrouteexist (city,city,distance)
Showshortestroute (city,city)
Showmustpassroutes (city,city,city)
Showmustnotpassroutes (city,city,city,city)
Writeroute (city,citylist,distance)
Reverse_list (Citylist,citylist,citylist)
Clauses
Road (beijing,shanghai,1462). Road (beijing,guangzhou,2107).
Road (beijing,kunming,3179). Road (beijing,xi_an,1165).
Road (shanghai,guangzhou,1811). Road (shanghai,kunmig,2677).
Road (shanghai,xi_an,1511). Road (guangzhou,kunming,2216).
Road (guangzhou,xi_an,2129). Road (kunming,xi_an,1942).
Connected (city1,city2,distance):-road (city1,city2,distance).
Connected (city1,city2,distance):-road (city2,city1,distance).
Member (X,[x|_]):-!.
Member (x,[_| L]):-member (x,l).
Route (city,city,visitedcities,visitedcities,0):-!.
Route (city1,city2,visitedcities,resultvisitedcities,distance):-
Connected (City1,x,distance1),
Not (Member (x,visitedcities)),
Route (x,city2,[x| VISITEDCITIES],RESULTVISITEDCITIES,DISTANCE2),
Distance=distance1+distance2.
Showallroutes (city1,city2):-
Write ("All routes between", City1, "and", City2, "are:/n"),
Route (City1,city2,[city1],visitedcities,distance),
Writeroute (city1,visitedcities,distance), NL,
Fail.
Showallroutes (_,_).
Showmustpassroutes (city1,city2,city3):-
Write ("All routes between", City1, "and", City2, "must Pass", City3, "are:/n/n"),
Route (City1,city2,[city1],visitedcities,distance),
Member (City3,visitedcities),
Writeroute (city1,visitedcities,distance), NL,
Fail.
Showmustpassroutes (_,_,_).
Showmustnotpassroutes (CITY1,CITY2,CITY3,CITY4):-
Write ("All routes between", City1, "and", City2, "must Pass", City3, "but does ' nt pass", City4, "are:/n/n"),
Route (City1,city2,[city1],visitedcities,distance),
Member (City3,visitedcities),
Not (Member (city4,visitedcities)),
Writeroute (city1,visitedcities,distance), NL,
Fail.
Showmustnotpassroutes (_,_,_,_).
Shorterrouteexist (city1,city2,distance):-
Route (City1,city2,[city1],_,distance1),
Distance1<distance,!.
Showshortestroute (city1,city2):-
Write ("Shortest route between", City1, "and", City2, "is:/n/n"),
Route (City1,city2,[city1],visitedcities,distance),
Not (Shorterrouteexist (city1,city2,distance)),
Writeroute (city1,visitedcities,distance), NL,
Fail.
Showshortestroute (_,_).
Writeroute (city1,[city1| Visitedcities],distance):-
!,
cities=[city1| Visitedcities],
Write ("", Cities, "The distance is", distance), NL.
Writeroute (_,visitedcities,distance):-
Reverse_list (visitedcities,[],visitedcities_reversed),
Write ("", visitedcities_reversed, "The distance is", distance), NL.
Reverse_list ([],list,list):-!.
Reverse_list ([h| Seenlistreset],interm,seenlist):-
Reverse_list (seenlistreset,[h| Interm],seenlist). Goal
Showshortestroute (beijing,kunming),
Showmustpassroutes (Beijing,kunming,shanghai),
Showmustnotpassroutes (Beijing,kunming,shanghai,guangzhou).
