搜索所有路径和图表的最短路径 - Prolog
我的代码中有turbo prolog的问题，它搜索所有路径和2个节点之间的图中的最短路径。
我遇到的问题是测试节点是否在列表中（完全在成员的子句中）
1 ---- b ---- 3
--- | ---
--- | -----
a |5 d
--- | -----
--- | ---
2 --- | --- 4
-- c --
for example we have for b--->c
([b,c],5) , ([b,a,c],3) and ([b,d,c],7) : possible paths.
([b,a,c],3) : the shortest path.
DOMAINS
list=Symbol *
PREDICATES
distance(Symbol, Symbol)
path1(Symbol, Symbol, list, integer)
path(Symbol, Symbol,list, list, integer)
distance(Symbol, list, integer)
member(Symbol, list)
shortest(Symbol, Symbol, list, integer)
CLAUSES
distance(a, b, 1).
distance(a, c, 2).
distance(b, d, 3).
distance(c, d, 4).
distance(b, c, 5).
distance(b, a, 1).
distance(c, a, 2).
distance(d, b, 3).
distance(d, c, 4).
distance(c, b, 5).
member(X, [X|T]).
member(X, [Y|T]) :- member(X, T).
absent(X, L) :-
member(X, L),
!,
fail.
absent(_, _).
/* find all paths */
path1(X, Y, L, C) :- path(X, Y, L, I, C).
path(X, X, [X], I, C) :- absent(X, I).
path(X, Y, [X|R], I, C) :-
distance(X, Z, A),
absent(Z, I),
path(Z, Y, R, [X|I], C1),
C = C1 + A
.
/* to find the shortest path */
shortest(X, Y, L, C) :-
path(X, Y, L, C),
path(X, Y, L1, C1),
C < C1.
没有找到相关结果
已邀请:
2 个回复
朗排谎纷瘟
edge(a,b,6). edge(a,c,1). edge(b,d,5). edge(c,e,4). edge(c,f,1). edge(d,h,3). edge(e,h,7). edge(f,g,2). edge(g,h,1). path(X,Y,M,[Y]) :- edge(X,Y,M). path(X,Y,P,[Z|T]) :- edge(X,Z,M),path(Z,Y,N,T), P is M+N. pravilo(X,Y,Z) :- assert(min(100)),assert(minpath([])),!, path(X,Y,K,PATH1), (min(Z),K<Z, retract(min(Z));assert(min(K))), minpath(Q),retract(minpath(Q)), assert(minpath([X|PATH1])), fail. ?- pravilo(a,h,X); write("Minimal Path:"), minpath(PATH), write(PATH), nl, write("Path weight:"), min(Z), write(Z).芭隘的盘石