Advent of Code Day 4.swift

extension Int {
  func digits() -> [Int] {
    var newN = self
    var result: [Int] = []
    while newN > 0 {
      let r = newN % 10
      newN = newN / 10
      result.append(r)
    }
    result.reverse()
    return result
  }
}

func isValid(_ digits: [Int]) -> Bool {
  return digits == digits.sorted() && digits.contains { d in digits.filter { $0 == d }.count == 2 }
}

let result =
  (136760...595730)
    .map { $0.digits() }
    .filter { isValid($0) }
    .count
print(result)