/Jeff(?:rey)?/

Well, I have two comments: a regex is a cool approach to take, and a regex is the wrong approach to take. You said yourself you could split and use a hash. That's what I'd do. I'd use a regex if I were trying to impress someone (which I'm not). But if you are, then here's my offering: 

$cities = "Here/There/Everywhere/There/Again/Here/Too";

$cities =~ s{
  ([^/]+)      # non-slashes (the city): \1
  /            # a /
  (?=          # look ahead for:...
    (?:        # group (not capture)
      [^/]* /  # city and /
    )*?        # 0 or more times, non-greedily
    \1         # is the city here again?
    (?: /|$ )  # a / or end-of-string
  )
}
{}gx;

[download]

_____________________________________________________
Jeff japhy Pinyan: Perl, regex, and perl hacker.
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;

In reply to Re: Re: Re: Removing duplicate substrings from a string - is a regex possible? by japhy
in thread Removing duplicate substrings from a string - is a regex possible? by iakobski

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.