刪除列表序言中的相鄰副本

Question

我是新來的Prolog，我需要從列表中刪除重複項，如下面的示例中所示。

?- remove([a,a,b,c,a,a,b,c,b,a,a],X). 
X = [a,b,c,a,b,c,b,a] 

Answer 1

如果我理解正確的話，你需要刪除鄰道重複。只需複製跳過第一個鄰接點的元素即可。我會讓你完成的代碼...

remove([X,X|Rest], [X|Rest1]) :- 
    !, % this commit avoid the logical alternative you'll code below 
    .... % recurse to get Rest1 from Rest 
remove([X|Rest], [X|Rest1]) :- 
    % recurse to get Rest1 from Rest 
% remember the base case !! 

編輯虛假指出，這種天真的刪除/ 2是馬車。我已經更正了添加一個remove/3謂詞，它爲會見證明做了複製，即帶有元素預見。

remove([X|Xs], [X|Ys]) :- 
    remove(X, Xs, Ys). 
remove(X, [X|Xs], Ys) :- 
    !, % discard the duplicate 
    ... % recurse to get Ys from Xs, with same witness 
remove(_, [X|Xs], [X|Ys]) :- 
    ... % the cut above ensure that here we must change witness when recursing 
% as always, remember the base case !!