Sfuffle a string to produce unique string and bring back to original string?

Question

is there any algo which shuffles characters of a string such that every shuffles return a unique combination, yet can be shuffled back to the original string if we know how many time it was shuffled?

this is what i have so far, yet it s not what i wanted. It can shuffle only (n/2)+1 times after that it comes back to the original string

//scramble data systematicslly
function Scramble($contents)
{
    $fsize=strlen($contents);
    $m=intval($fsize/2);
    $buffer=$contents[$m];
    for($i = 1; $i < $fsize; $i++)
    { 
        if($i%2==0)
        {
            if($m+$i<=$fsize){$buffer.= $contents[$m+$i];}
            if($m-$i>=0){$buffer.= $contents[$m-$i];}
        }else
        {
            if($m+$i<=$fsize){$buffer.= $contents[$m+$i];}
            if($m-$i>=0){$buffer.= $contents[$m-$i];}
        }
    }    
    return $buffer;
}

for `aaaaa` there is only one possible shuffle, what do you want the algorithm to do in this case? — amit, Aug 05 '13 at 14:47
@NokImchen Where the exceptions span? what about `aaaaab`, there are only 6 different combinations for it. — amit, Aug 05 '13 at 14:50
@Geobits after shuffling with Fisher-Yates shuffle, can we bring back to the original string if we know the key used? — Nok Imchen, Aug 05 '13 at 14:54
Just to clarify, are you trying generate each possible combination of characters once? Then possibly starting over again. — Flosculus, Aug 05 '13 at 14:56
See http://stackoverflow.com/a/2031708/1516296. Algorithm is in C++. I think it should do what you want. — JoshG79, Aug 05 '13 at 14:56
@Geobits, ah, i was too in a hurry that i went to google instead, thanks a lot for point :) wish i could mark u as accepted answer :) — Nok Imchen, Aug 05 '13 at 14:56

score -1 · Answer 1 · edited Jun 16 '14 at 22:16

-1

Create a function that performs an operation. If you do this you know the process so to find the original string, create another function that takes an integer as a parameter, and do the opposite of your original function n times.

edited Jun 16 '14 at 22:16

BenMorel

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answered Aug 05 '13 at 14:57

Martin Bean

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Sfuffle a string to produce unique string and bring back to original string?

1 Answers1