Swapping values of two variables

[tony.clarke5 at googlemail.com]

On Jan 30, 12:29 am, Eric Kang <y... at sfu.ca> wrote:
> In python, I set:
>
> x=1
> y=3
>
> z = x
> x = y
> y = z
>
> This gave me 3 1, which are the values of x and y swapped.
> The following would have given me the same result:
> x, y = y, x
>
> But could the swapping be done using less extra memory than this? What is the minimum amount of extra memory required to exchange two 32-bit quantities? What would be the pseudocode that achieves this minimum?

How about:
def transpose(x, y):
    print x, y, 'becomes: ',
    x = x + y
    y = x - y
    x = x - y
    print x, ' ', y

transpose(1,3)
transpose (9,8)