Description mentions caching the results, but it is not tested. Either this should be a requirement and hence tested, or should be removed from the description. If you require caching, how should void functions be dealt with? The description could benefit from clearer guidelines.

Agreed, but I also think that even with those utilities, this task isn't trivial to do correctly. Of course, if you copy everything and turn things into lvalues, it is. But it took me 30 minutes to put together a solution that keeps value categories intact. I assumed there would be tests for that, and also the caching, but apparently not

wow, this is interesting, I didn't thought about that

great kata, thank you, i'm really learned a lot!

nice

这种解法无疑是聪明的，但是可能会造成理解与额外依赖性问题。

hahaha that's "c++" xd

People often upvote the solution they understand or the one similar to what they did, so it's more of the most popular solution rather than most clever or fastest

that's costly

what's the difference between the cbegin and begin, vice versa cend

Really clever way to avoid needing to divide and typecast the result to float/double! And even accounts for yourself being a part of the class 'avg,' though at first glance one might think it doesn't. It does!

nice way to avoid costly division.