Comment by Peritract

In general, the problems require less background knowledge than other coding puzzles. They're not always accessible without knowing a particular algorithm, but they're more 'can you think through a problem' than 'have you done this module'.

That's not the same as saying they're easy, but it's a different kind of barrier, and (in my opinion) more a test of 'can you think?' than 'did you do a CS degree?'