Find Duplicate Elements In Array Using Swift

Question

How to find Duplicate Elements in Array? I have array of phone numbers so in the phone numbers i should start searching from the right side to the left side and find similar 6 integers. then i should print them out.

Answer 1

Feeling ~clever~. Given an array of Ints

let x = [1, 1, 2, 3, 4, 5, 5]
let duplicates = Array(Set(x.filter({ (i: Int) in x.filter({ $0 == i }).count > 1})))
// [1, 5]

Please note, this is horrendously inefficient for everyone involved, including the compiler, and you.

I'm just showing off.

Edit: lol someone downvoted this, which leads me to reiterate, just in case: please DO NOT USE THIS in production or anywhere else.