Build a new array containing the indexes of the elements where sequences of equal strings start. For instance: 
 @a = qw(a a b b c c c d e e e e e f f)
 #   ix: 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1
 #       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4
 #start: * - * - * - - * * - - - - * -
 @start = (0, 2, 4, 7, 8, 13);

[download]
Then just perform the binary over @start, using $a[$start[$ix]] as the search key.

Once you find the index $ix corresponding to the searched element, the start and end offsets will be $start[$ix] and $start[$ix+1] - 1

In reply to Re: Modified Binary Search by salva
in thread Modified Binary Search by Limbic~Region

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.