The example tests you get when pressing Test have much much fewer tests. Passing those is not a guarantee that you're going to pass the real test suite. If you failed a test in the real test suite, that would be something to get to the bottom of.

(also, I later ran your code, and it's got a severe bug in it)

My code passed the tests but failed the attempt. I don't know why, it was basically exactly this. I had to forfeit. Annoyed.