Re: swapping two numbers

[Leonid Grinberg]

not in-place cause it's 3 lines, but does not use an external temporay
value, and should be language-independent:
  x = x + y
  y = x - y
  x = x - y
(IIRC my high school BASIC teacher taught us that)

Yeah, that works. Who said that it can't be 3 lines.