Which search method is considered more efficient: array traversal or key-based lookup in a dictionary?

Accessing an element by key in a dictionary is considered a more efficient search method compared to iterating through an array.

Reasons:

• Dictionary is implemented based on a hash table, which provides an average access time of O(1).
• Array iteration (linear search) requires checking each element, with a search time of O(n).

Example in Swift:

let array = [1, 2, 3, 4, 5]
let dictionary = [1: "one", 2: "two", 3: "three"]

// Searching in array
if array.contains(3) {
    print("Found")
}

// Searching by key in dictionary
if let value = dictionary[3] {
    print("Found: \(value)")
}

Thus, if you need to frequently search for elements by key, it is better to use a dictionary.