reverse and intersect problems

[programmer720]

I'm looking for these 2 algorithms...
REVERSE: given a list L, find the reverse R of L (top-level elements only). For example,
?-reverse([ ], R). should answer R = [ ]
?-reverse([1, 2, [3, 4]], R). should answer R = [[3, 4], 2, 1].

INTERSECT: given sets X and Y (represented as lists), intersect(X, Y, I) finds I which is X¿Y.

Thanks a lot.

 

[phjy]

i don't know about INTERSECT at the moment... but for REVERSE you can have:

reverse(L, Reversed) :-
reverse1(L, [], Reversed).
reverse1([], R, R).
reverse1([H|ToGo], Sofar, Reversed) :-
reverse1(ToGo, [H|Sofar], Reversed).