How to check list A contains any value from list B?

Question

List A:

1, 2, 3, 4

List B:

2, 5

How to check if list A contains any value from list B?

e.g. someth

Answer 1

For faster and short solution you can use HashSet instead of List.

a.Overlaps(b);

Overlaps documentation

This method is an O(n) instead of O(n^2) with two lists.