in reply to Re^3: Finding repeat sequences. (only regex)
in thread Finding repeat sequences.

Nice reversal of the logic and closer:

$s = 'aaaabaaaabaaaaabaaaab';;
$s =~ /^((.*?).*?)\2*\1$/ and print "$2/$1";;
a/aaaabaaaab

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Re^5: Finding repeat sequences. (only regex!)
by tye (Sage) on Jun 18, 2013 at 21:17 UTC

    I think I had \1 and \2 backward. Then you just have to disallow the trivial solution: 

    $s = 'aaaabaaaabaaaaabaaaab';
$s =~ /^((.*?).*?)(?=.)\1*\2$/ and print "$2/$1";

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    (Update: Dropped the unneeded () around \1 that I had introduced while debugging. You probably also need to change .*? to .* so you get the longest solution not the shortest.)

    - tye        

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