从 Prolog 中的列表列表中删除重复元素 [英] Removing Duplicate Elements from List of Lists in Prolog

问题描述

我正在研究如何在 Prolog 的列表中删除重复元素.

I am trying to work out how to remove duplicate elements in a list of lists in Prolog.

例如:
输入:[[1,2,3],[5,6],[3,4],[1,7]]

预期输出:[[1,2,3],[5,6],[4],[7]]

我知道我可以使用谓词 sort/2 来删除单个列表中的重复项，但是如何让它在多个列表中工作?

I know I can use the predicate sort/2 to remove duplicates in a single list, but how do I get it to work across multiple lists?

推荐答案

这是我的尝试.希望你已经做了一些尝试来解决它并从中学习......无论如何，如果你仍然没有想出任何东西，请查看以下代码:

Here is my attempt. Hope you've made some attempts to solve it and learn from this...Anyway if you still didn't come up with anything take a look at the following code:

 remove_dupl(InL, OutL):- remove_dupl(InL, [], OutL1),remove_empty(OutL1,OutL).

remove_dupl([],_,[]).
remove_dupl([H|T],L,[[H1]|T2]):-
              H=[H1], \+member(H1,L), 
              remove_dupl(T,[H1|L],T2).
remove_dupl([H|T],L,[[H1|T2]|T3]):- 
              H=[H1|T1], \+member(H1,L), 
              remove_dupl([T1|T],[H1|L],[T2|T3]).
remove_dupl([H|T],L,T2):- 
              H=[H1|T1], member(H1,L), 
              remove_dupl([T1|T],L,T2).
remove_dupl([H|T],L,[[]|T2]):- 
              H=[H1], member(H1,L), 
              remove_dupl(T,L,T2).

remove_empty([],[]).
remove_empty([[]|T],T1):-remove_empty(T,T1).
remove_empty([[H|T]|T1],[[H|T]|T2]):-remove_empty(T1,T2).

也许不是最有效的解决方案.示例:

Maybe not the most efficient solution. Example:

?- remove_dupl([[1,2,3],[5,6],[3,4],[1,7]],L).
L = [[1, 2, 3], [5, 6], [4], [7]] ;
false.

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