OpenEuphoria

Re: An Applied Algorithmic Activity:

• Posted by Matt Lewis <matthewwalkerlewis at yahoo.com> Jun 29, 2004
• 437 views

Patrick Barnes wrote:
> 
> Lets say we want to step through the numbers 1 to N, in a particular
> order. The order of the numbers can be arbitrary, but each number can
> only be visited once, and the order of the visits should be seeded by
> a number passed to it.
> 
> For example:
> 1923840657
> 0123456798
> 7648235910
> 
> It seems like it needs some sort of hash value, but I couldn't for the
> life of me figure out how.
> How would you suggest I do this? Each seed doesn't have to generate a
> unique result, but it would be nice. 

One way to do this is to iterate using a number that is relatively prime 
to N.  If two numbers are relatively prime, it means that their greatest
common divisor is 1.

So suppose N = 10.  You could use 7, to pick a number at random, and
you would get (modulo 10, of course):

7, 4, 1, 8, 5, 2, 9, 6, 3, 0

In euphoria:

integer N, n, p
N = 10
p = 7
n = 0
for i = 1 to N do
    n = remainder( n + p, N )
    ? n
end for

Matt Lewis