How long does it take to perform a search (for example, using the contains method) in List and Set collections?

For List, searching with contains has a computational complexity of O(n), where n is the number of elements in the list. This is because, in the worst case, all elements need to be checked to determine if the element exists.

For Set, searching with contains has an average computational complexity of O(1). This is achieved by using a hash table for internal storage of elements. In an ideal case (good hash function and no collisions), the search takes constant time. In the worst case (many collisions), the complexity can approach O(n), but this is rare in practice.