Codility Missing Integer (https://codility.com/demo/results/demoKGH8FF-AP6/)

CodilityMissingInteger.scala

object Solution {
    def solution(A: Array[Int]): Int = {
        val (results, _) = A.sorted.foldLeft((0, 0)) { (t, item) =>
            val (current, last) = t

            val next = last + 1
            item match {
                case x if x < 0 => (current, last)
                case `last` => (item, item)
                case `next` => (item, item)
                case _ => return next
            }
        }

        results + 1
    }
}