>>>>Fabio,
>>>>
>>>>Your "do not move anything" assumption is not right, it is not how the current code works. It would require moving AAAAABB, then AAAAAB, then AAAAA.
>>>>
>>>>There do exist other input strings that require more movement when proccessed right to left, it is a shame that you don't see this fact.
>>>>
>>>>But the whole underlying fallacy of moving the same character more than once in any algorithm is what makes it O(n²), which is a foolish waste of CPU time when it can be done O(n) as I've posted in the C++ code.
>>>>
>>>
>>>Someone has the patience to explain as the thing to David works.
>>>Thanks.
>>
>>I see the difference Fabio.
>>
>>In a right to left you never move a char too many, ie one that you will discard later, you move processed data
>>
>>In a left to right you are likely to move chars that you will discard later, you move non processed data
>>
>>

>>Left >> right = move chars that will not necessarily be in the end result
>>
>>
>>Right >> left = never move chars that are not in the end result
>>
>>eg: take * out
>>
>>12*4*6*89
>>
>>Left >> right
>>move 1: 4*6*89   6 chars  where 2 not in the end result
>>move 2: 6*89     4 chars  where 1 not in the end result
>>move 3: 89       2 chars  where 0 not in the end result
>>                ---
>>                12 chars  where 3 not in the end result
>>
>>Right to left
>>
>>move 1: 89       2 chars where 0 not in the end result
>>move 2: 689      3 chars where 0 not in the end result
>>move 3: 4689     4 chars where 0 not in the end result
>>                ---
>>                 9 chars where 0 not in the end result
>>

>
>Thanks Gregory for your patience.
>
>VFPT can easily implement a best code for CHRTRAN ( max 1 hour of works ):
>

>if Param2Lengh=Param3Lengh => none char is removed, then use a on place trasl
>   for prtReadWrite^=1 .... ++
>    { if ...
>         prtReadWrite^=...
>     }
>else => use a two pointers a Read and a Write
>    prtWrite^=1
>    for prtRead^=1 ++
>     { if ...
>        ....
>        prtWrite^=
>        prtWrite++
>      }
>    stringLen = prtWrite-prtStart
>

I know it can be done with two pointers (and a translation table)

cheers,