I did not know that Java has functional patterns / iterators. Nice!

i am about half your age, so you may consider me a kid

all i wanna say is that it's not all about the big O; by saying that my solution is 10x faster i'm just giving an example of two O(n) implementations that are quite different

and if you don't get it, my first comment was a criticism of HotMugger's statements

Are you a kid? Are you trying to elicit a kid argument with "my solution is 10x faster. No, my solution is 100x faster. No, it's infinity faster. No, its infinity x infinity faster".

Grow up.

ChatGPT moment

not all O(n) are the same, coefficients vary. the term suboptimal applies well

my solution is about 10x faster than this one

the pushes will just assign capacity to the next power of 2 when len is a power of 2. and there will be no moving of elements unless the next capacity is at least 2^16 or even higher

still, it would be best to use with_capacity and omit capacity checks

wdym consultant?

also sorry for the dead code and putting the main function at the very end

it wouldnt be complete without iterators :)

needs more iterators apparently

I found the consultant :)

risky :D

Although that is all true to my recollection...why bother doing a conversion into a vector an returning it? It wants you to return a vector so I gave it one. In hindsight I do wish I allocated the size at creation if that was what your getting at.

This is nice to read, but has sub-optimal performance. Every push will make a slightly bigger copy of 'vec' to keep up with size. So for n elements, the first push copies 1, then 2, then 3, ... , then n elements, resulting in O(n^2) runtime (Gauß). Dynamically sized data types are a lie.