> PE is untimed and no one is looking over my shoulder.
Fair enough. I suppose many programmers suffer from anxiety during those interviews.
> Plus there's a right answer---no hidden test suite.
This statement makes no sense, though.
Both Project Euler and LeetCode-type of problems have a right answer, in fact, LeetCode-type of problems have more than one right answer, making them even easier than Project Euler problems.
Also, having a hidden test suite means nothing because the (single) test used to verify the answer for a Project Euler problem is also hidden.
