4673번 '셀프 넘버'

var set: Set<Int> = []
func add(string: String) -> Int{
    var sum = 0
    for i in 0..<string.count{
        let result = string[string.index(string.startIndex, offsetBy: i)]
        sum += Int(result.description)!
    }
    return sum + Int(string)!
}
for i in 1...10000{
    set.update(with: add(string: String(i)))
}
for i in 1...10000{
    if(!set.contains(i)){
        print(i)
    }
}

Set 자료구조를 활용하여 푼다.