I'd use this function:

index(STRING, SUBSTRING, POSITION) -- Returns the position of the first occurrence of SUBSTRING in STRING at or after POSITION. If you don't specify POSITION, the search starts at the beginning of STRING

You'll be looking for the first occurrence of the CURRENT character in the string AFTER the current position. Any way you look at it, it is O(n^2) on the length of your string. At least this solution doesn't use additional memory like the solution with the hash.

In reply to Re: Recognizing duplicates by RaduH
in thread Recognizing duplicates by b4swine

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