[Deestan]

I'm sorry. That one uses a hidden temp storage for the intermediate calculations.

We were looking for the solution based on XOR which works with only two registers.

We wish you luck with your job search elsewhere.

[kadoban]

That's not what someone giving even this poor interview question would answer with. It's also not true.

These interview questions are fairly shit, but they're not _that_ shit, and the people giving them are doing their best.