> The second one is definitely not "the right idea". It tries to do it with string manipulations, which (regardless of the fact that it does so incorrectly) is

> The second one is definitely not "the right idea". It tries to do it with string manipulations, which (regardless of the fact that it does so incorrectly) is completely the wrong approach. This one is actually "better" than the other in the paradoxical sense I mentioned above, because I could reject it the moment I saw it convert the number to a string. In this case string ops are a worse idea, but as I said before, this is not generally true of Python, at least when using CPython. Eg. the string method is significantly the faster in this example: # https://stackoverflow.com/a/20918545/1763356 def reverse_mask(x): x = ((x & 0x55555555) << 1) | ((x & 0xAAAAAAAA) >> 1) x = ((x & 0x33333333) << 2) | ((x & 0xCCCCCCCC) >> 2) x = ((x & 0x0F0F0F0F) << 4) | ((x & 0xF0F0F0F0) >> 4) x = ((x & 0x00FF00FF) << 8) | ((x & 0xFF00FF00) >> 8) x = ((x & 0x0000FFFF) << 16) | ((x & 0xFFFF0000) >> 16) return x # My ver def reverse_format(x): return int(f"{x:032b}"[::-1], 2) Python's dynamic object overhead (and to a lesser extent, interpreter overhead) makes a lot of seemingly-expensive operations not matter very much.