http://www.perlmonks.org?node_id=527732


in reply to Longest repeated string...

Yzzyx,
First, you are going to want to google for 'longest common substring' as your brute force approach is definately not the right way to go.

Second, the idiom you don't understand deserves to be in the "Perl Idioms Explained" category. In a nutshell, Perl will do what you mean (DWYM) when you give it proper context. A list in scalar context returns the number of items in the list.

Third - good luck. No matter what algorithm you use (LCS) and what language you use (C/Assembler), this is not going to be a fast answer.

Cheers - L~R

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Re^2: Longest repeated string...
by japhy (Canon) on Feb 03, 2006 at 17:37 UTC
    A list in scalar context returns the number of items in the list. Not quite.

    A list assignment in scalar context returns the number of items in the right-hand list.

    Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
    How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart
[reply]
      japhy,
      Thanks - which is why I said this deserved an entry in "Perl Idioms Explained". I could argue that there is no assignment going on in: 
      while ( @array ) { ... }
# or
print "Array is empty\n" if ! @array;

      [download]
      but then we could discuss the difference between lists and arrays and it wouldn't be worth it. I think I was able to get the OP to understand even if I wasn't completely accurate. I do think it would make for a good entry in "Perl Idioms Explained".

      Cheers - L~R

[reply]
[d/l]
        If you don't, I will. (Make the PIE node for this idiom, I mean.)
        Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
        How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart
[reply]

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