OpenEuphoria

Permutation function

• Posted by thomas at columbus.rr.com Nov 12, 2002
• 546 views

I read an e-mail about somebody looking for permutations.. Sorry, I'm a
bit short on time so I won't have a chance to look for that e-mail or
test out the code thoroughly (though my quick test shows that it works).
Here is a little function that I have been using to find permutations.
You call it with the set of characters you want to be used (ex: {'A',
'B', 'C'} or {'1', '2', '3'}) and the length of each permutation (ex: 3,
6, 9).

It's not the most optimized function in the world, but so far I haven't
had any problems. I was recently working with the code, so it may not
work exactly right (sorry!). I thought if I sent it to the list I could
get some c&c on it. Tell me what you think!

~Tom

-- code --
function GetPermutations( sequence characters, atom len )
 sequence final, combo
 integer chars
 atom doit doit = 1
 final = {}
 combo = repeat(1, len)
 chars = length(characters)
 while doit do
  final = append(final, combo)
  combo[1] += 1
  for i = 1 to len do
   if combo[i] > chars then
    if i = len then
     combo[i] = chars
     final = append(final, combo)
     doit = 0
     exit
    else
     combo[i..i+1] = {1, combo[i+1]+1}
    end if
   end if
  end for
 end while
 for i = 1 to length(final) do
  for p = 1 to length(final[i]) do
   final[i][p] = characters[final[i][p]]
   end for
  end for
 return final
end function
-- code --

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