import Foundation
func getMissingAlphabetChars(_ input: String) -> [Character] {
// Full alphabet as a Set
let alphabet = Set("abcdefghijklmnopqrstuvwxyz")
// Normalize input: lowercase + keep only letters a–z
let present = Set(
input.lowercased().filter { $0.isLetter && $0.isASCII && $0.isLowercase }
)
// Difference: alphabet minus present letters
return Array(alphabet.subtracting(present)).sorted()
}
let missing = getMissingAlphabetChars("Swift Programming")
print(missing)
/*
run:
["b", "c", "d", "e", "h", "j", "k", "l", "q", "u", "v", "x", "y", "z"]
*/