Benchmark results: 
     20000 26 20
               Rate          hdb RobertCraven     kennethk          xx
+x
hdb          2.57/s           --          -8%         -55%         -84
+%
RobertCraven 2.81/s           9%           --         -51%         -82
+%
kennethk     5.77/s         124%         106%           --         -64
+%
xxx          15.8/s         515%         464%         174%           -
+-

     20000  4 20
               Rate          hdb RobertCraven          xxx     kenneth
+k
hdb          2.82/s           --         -11%         -46%         -54
+%
RobertCraven 3.18/s          13%           --         -40%         -48
+%
xxx          5.28/s          87%          66%           --         -13
+%
kennethk     6.08/s         115%          91%          15%           -
+-

    200000 26  5
         s/iter kennethk      xxx
kennethk   2.05       --     -32%
xxx        1.40      47%       --

    200000  4  5
         s/iter      xxx kennethk
xxx        24.6       --     -92%
kennethk   2.07    1090%       --

[download]
Never been particularly proficient with pack, but it looks like your approach falls apart with the restricted character set. OTOH, that's an impressive result for [20000,26,20]. I imagine optimizing your unpack could yield some impressive optimization.

And, FYI, the windowing approach is about 30x slower than other options with only 1 letter.

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

In reply to Re^3: suffix array efficiency by kennethk
in thread suffix array efficiency by RobertCraven

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.