Re: Newbie without any idea!!!

This could be a solution:

sum(0, []).
sum(X, L) :-
flatten(L, F),
sum1(X, F, 0).
sum1(X, [], X).
sum1(X, [H|T], R) :-
R1 is R + H,
sum1(X, T, R1).

Note that also the following (for example) are permitted:

?- sum(X, [[]]).
?- sum(X, [[2,2],2]).

I dont know if this is undesirable.
Of course, the list must be an integer list.

Cheers, M


<leo@xxxxxxxxxxxxxx> ha scritto nel messaggio
news:1120030257.119295.55300@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Hi! The following is the requirement of the program
>
> sum(X, 4) : X would be evaluated to 4.
> sum(X, [2,4]): X would be evaluated to 6.
> sum(X, [2,[2,2]]): X would be evaluated to 6.
>
> How can I implement by Prolog?
> I have the following idea.
> sum(X,X).
> sum(X,[H|T]):-..............
>
> Thanks!
> Ming
>


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