Requirements should be changed tbh, it's pretty stupid that you're expected to pad when unneccessary.

we think same xd..... simplicity is best

Ohhhh...

C# Translation

Lua translation!

Approved

python new test frameworks

for anyone solving this currently and confused by this edgecase: The solver appears to expect the output array to grow by at least 2 on each iteration, so if your result is an empty array after trimming leading and trailing zeroes you can create a new array of list.length + 2 and fill it with zeroes.

thought this will be voted most... go for the shortest version for the sake of it... damn..

first time I solved something so easily and it was the first solution (I'm always trying to get the same solution as the first, even if I know how to write it less elegantly)

I'm not too sure, but I think these builtins are internally written in C, making them automatically blazing fast. Calling the solution "horribly inefficient" is really dramatic. On the grand scheme of things, this is still an O(n) solution. It is also incredibly readable. I have run some cursory benchmarks and the "inefficient" method gobsmacks yours for all list lengths I've tried (we're talking around more than 3x faster than yours). Take this with a grain of salt since they're informal tests, but it should hopefully make you reconsider making hasty performance comments in the future. I'll attach it spoilered below.