report/src/hs.pl

   1 :- [diagnosis].
   2 %Function to add variable for uniqueness checking.
   3 isHittingSetTree(Tree) :-
   4         isHittingSetTree2(Tree, []).
   5
   6 %When the end of branch has been reached.
   7 isHittingSetTree2(leaf, _).
   8 %When a node turns empty.
   9 isHittingSetTree2(node([], []), _).
  10 %When a node isn't empty.
  11 isHittingSetTree2(node([CurLabel|Labels], [CurChild|Children]), VisitedLabels) :-
  12         %Check if label has already been used up in the tree.
  13         not(member(CurLabel,VisitedLabels)),
  14         %Append label to list of checked labels
  15         append(VisitedLabels, [CurLabel], UpdatedVisitedLabels),
  16         %Recursively search into depth of branch.
  17         isHittingSetTree2(CurChild, Appended),
  18         %Recursively search into width of node.
  19         isHittingSetTree2(node(Labels, UpdatedVisitedLabels), VisitedLabels).
  20 %If there are more or less labels then children, the tree will not match and
  21 %the function will rightfully report false.