Every element in List A appears only once, and the same is true for List B. How can I efficiently create a list of the element in A that don't appear in B? Obviously, I can just do this:
Do[A=DeleteDuplicates[A,B[[i]]],{i,1,Length[B]}];
...but that's painfully slow for very long lists. Also, it doesn't take advantage of my knowledge that every element in each list is unique within the list.
Thanks!
Complement[B, A]
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