I’d like to ask the good people of this community that, if you do know the solution or figure it out, that you not share the answer here. Feel free to announce your success, but there’s something to be said for discovering the answer completely unaided, even if it takes years.
It’s embarrassingly obvious once you see it though.
The function is not complicated, and the solution does not require brute force. In fact, it’s quite elegant in its simplicity.
And when you get it, you then get to take a step back and admire how the creator was able to set up the numbers given to almost point to the red herring answer. Not a lazy puzzle at all.