I saw some floats provided, so I chose to reject strings rather than select integers.

Thank you!

It matches all whitespace characters like tabs or newlines. It's not better, in fact it's likely slower, but it might be more robust in a real world scenario.

this is longer and more complicated than the original, so how do you think it's better?

Nice edge case addition

Nice!

Nice. Very clean, succinct, readable.

Speed isn't always important, but at the time of this comment, the function above is the fastest of all the functions that don't return errors or incorrect results.

if the string contains 2 spaces this code will return 1

takes a list of non-negative integers and strings

I'd assume that when we remove all the strings, the only things left are the integers.

Technically wrong, as the specs said: "remove all the strings". The tests are not good enough to catch that though.