## Hints
Try to avoid code repetition, use private helper functions if you can.

And you might consider using a single `Boolean` expression instead of `if-else` for better readability. See [here](http://cs.wellesley.edu/~cs111/spring00/lectures/boolean-simplification.html) on how this could be done (the link is for Java, but of course the logic is valid for Scala, too).