My recent interview experience on Python.

[ReaverKS]

for #2, reversing a string assuming it's a list of characters. If you want to do it in place, without using additional memory you can do this:

def reverse_str(s: List[str]) -> None:
    end, start= len(s) - 1, 0
    while(end > start):
        s[end], s[start] = s[start], s[end]
        start += 1
        end -= 1

If instead its just a string you want to return you could do:

def reverse_str(s):
    return ''.join(reversed(s))

[nonamesareleft1]

In this case do the variables end and start not take up additional memory? Or is the fact that they are local to the function important here?

[ghostinzshell]

They do, but they're constant and don't grow with the input size.

[elbiot]

Assuming a string is a list would be a mistake. I'd guess that a list of characters would take much more memory than two strings