I recommend removing step 3 from the instructions. It is very confusing, and not only because of the bad English. The fact that it has its own number and associated text seems to imply that something should be done here, but nothing actually needs to be done in this step. I wasted several minutes trying to decipher this part.

The F# version has a bug in the test that refers to the function as "friend", but the boilerplate code uses the name "friendOrFoe". I had to modify the test before I was allowed to submit.

Although it's easy to deduce what you want by looking at the tests, it should be explained more clearly in the instructions what is supposed to be done with the input to create the output.

I initially just did the textbook hello world, but something made me come back and do it in a more interesting way.

@g964 The solution of mine that you see is in Scala. I never submitted my Dart version of the code. Also, I don't know if you can see my last edit of the Dart code, but that was something incomplete that I abandoned after trying to rework it because the test of "print(a1==null)" outputted "false" in every test including when the input actually was null.

The code should have exited with an early return before it ever got to the sort part.

I forfeited on the Dart version of this because my test of a1==null never returned true when the input actually was null. That made it impossible for me to handle the cases when null parameters were passed. Upon unlocking the solutions, I saw that this technique was widely used and worked for others. I'm wondering if those solutions were submitted prior to Dart's upgrade to null safety. If I test on my own computer by trying to use a null parameter, the code doesn't compile, but your tests here clearly are submitting null in some of the tests. I noticed that none of the solutions explicitly made the List nullable and Dart makes everything non-nullable by default since the introduction of null safety.

Half of the solutions did not memoize, as requested in the instructions.

I was wondering why this was 8kyu and I was assembling a list of all the words in order of how I thought they were supposed to be ranked. I got stopped several times as new words appeared. I still don't know what a Souther is! Just when I was ready to abandon this exercise, I reread the instructions and figured out what they actually wanted, which was far simpler than what I thought they wanted.

I started building a list of all the words and wondered why they didn't provide one for us in the instructions. After several rounds of adding new words, I read the instructions again and finally figured out that every group of 3 words is supposed to be rearranged in exactly the same way.

I came here specifically to say this and saw that you already did. I wrote a lot of extra code to handle parentheses and realized after submission that none of the top solutions handled them.