[Kotlin and Swift] Coding Challenge - Codility - Counting Elements - MissingInteger and PermCheck

We worked on the Counting Elements Codility challenges: https://app.codility.com/programmers/lessons/4-counting_elements/

The first one we did in Kotlin, the second one in Swift.

MissingInteger was VERY easy, able to knock that out quickly.

PermCheck was a bit harder, but we had to set up Xcode Playground for the challenge and we needed to refresh our memory on immutable array's in Swift.

Our reference checks were interesting since they had pretty different answers from what we came up with:

https://github.com/HungUnicorn/Kotlin-Solution-for-Codility-Lesson/tree/master/src/d_counting_elements

https://github.com/HungUnicorn/Kotlin-Solution-for-Codility-Lesson/tree/master/src/d_counting_elements