Which option is better for finding elements — array or set?

A set (Set) is usually better suited for searching elements than an array. This is because a set implements a data structure optimized for fast search — add, remove, and check for the presence of an element operations are performed in amortized O(1) time. In contrast, searching for an element in an array requires iterating through all elements (O(n)), which is less efficient with large data volumes.

Example in Swift:

let array = [1, 2, 3, 4, 5]
let set: Set = [1, 2, 3, 4, 5]

// Search in array
let containsInArray = array.contains(3) // O(n)

// Search in set
let containsInSet = set.contains(3) // O(1)

Therefore, if search speed and element uniqueness are important, it is better to use a Set.