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pl:prolog:pllib:list_intersection [2019/06/27 15:50] |
pl:prolog:pllib:list_intersection [2019/06/27 15:50] (aktualna) |
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| + | ====== List intersection ====== | ||
| + | {{tag>lists}} | ||
| + | ===== Description ===== | ||
| + | Finding the intersection of two lists. | ||
| + | |||
| + | **Source**: The Art of Prolog | ||
| + | ===== Download ===== | ||
| + | Program source code: {{list_intersection.pl}} | ||
| + | ===== Listing ===== | ||
| + | <code prolog> | ||
| + | /* | ||
| + | intersection(Xs,Ys,Is) :- Is is the intersection of the elements in Xs and Ys. | ||
| + | */ | ||
| + | |||
| + | intersection([X|Xs],Ys,[X|Is]) :- member(X,Ys), intersection(Xs,Ys,Is). | ||
| + | intersection([X|Xs],Ys,Is) :- nonmember(X,Ys), intersection(Xs,Ys,Is). | ||
| + | intersection([],Ys,[]). | ||
| + | /* | ||
| + | nonmember(X,Xs) :- X is not a member of the list Xs. | ||
| + | */ | ||
| + | nonmember(X,[Y|Ys]) :- X \== Y, nonmember(X,Ys). | ||
| + | nonmember(X,[]). | ||
| + | |||
| + | % Program 13.2 Finding the intersection of two lists | ||
| + | </code> | ||
| + | ===== Comments ===== | ||
