参数中的结果不正确

时间:2011-11-30 17:48:25

标签: recursion prolog

所以我有这段序言:

my_avalia(A, R) :-
    A == "Koza" -> koza(R, 0, 0, e, 89).

koza(R, _, _, _, 87) :-
    !,
    write(R).

koza(R, X, Y, V, C) :-
    movex(V, X, X1),
    movey(V, Y, Y1),
    confirma(X1, Y1, Z),
    Z == 1 -> (append(R, [emFrente], U),
            L is (C - 1),
            koza(U, X1, Y1, V, L)).

问题是,当我在koza()处写“R”时,它具有正确的值,但是当我将其称为my_avalia时,它会以空列表结束:

my_avalia( “讲座”,R)。

我的递归可能不正确,但我真的不知道它有什么问题。 提前谢谢。

其他功能:

movex(X,Y,R):-(X==o)->(R is Y-1).
movex(X,Y,R):-(X==n)->(R is Y).
movex(X,Y,R):-(X==s)->(R is Y).
movex(X,Y,R):-(X==e)->(R is Y+1).

movey(X,Y,R):-(X==n)->(R is Y-1).
movey(X,Y,R):-(X==s)->(R is Y+1).
movey(X,Y,R):-(X==o)->(R is Y).
movey(X,Y,R):-(X==e)->(R is Y).

confirma(X,Y,R):-(santafe(X,Y),R is 1); (R is 0).

我明白了......这是一个愚蠢的错误。

koza([], _, _, _, 87) :-!.
koza(R, X, Y, V, C) :-
    movex(V, X, X1),
    movey(V, Y, Y1),
    confirma(X1, Y1, Z),
    Z == 1 -> (L is (C - 1),
            koza(U, X1, Y1, V, L),
            append(U, [emFrente], R)).

无论如何,谢谢。

1 个答案:

答案 0 :(得分:0)

koza([], _, _, _, 87) :-!.
koza(R, X, Y, V, C) :-
    movex(V, X, X1),
    movey(V, Y, Y1),
    confirma(X1, Y1, Z),
    Z == 1 -> (L is (C - 1),
            koza(U, X1, Y1, V, L),
            append(U, [emFrente], R)).