Actually looking at their "brute force" solution, what I was referring to as brute force was their "greedy" algorithm, and the first optimization I came up with was the most optimal solution. I'd call that a very natural strategy to take -- try doing the words simultaneously instead of separately, and you see it.

I don't even see that as DP.

Not everybody will be as quick as me, but there are plenty of people that don't spend a month practicing for a Google interview. If somebody is practicing solving data structures problems for the first time in their life, that's fine -- maybe they went to a substandard school. But if they have to spend a month refreshing any time they want a job, it means their brain drops skills they learn that are closely related to the job they do. That means their experience is worthless -- they aren't retaining it, long-term.