I may be missing something here, but if you are only testing the least significant bit aren't you simply testing whether the integers are even or odd?

Since there are only two possible groups (even or odd), it seems overkill to use a hash to store all possible combinations of integers in each group. Why not store the odd numbers (since you want the least significant bit set) in an array, then compute the possible combinations afterwards? See Math::Combinatorics for one option.

Update: If you need the results in a hash, it could be populated while constructing the combinations of odd numbers. I suspect that most of the time (and memory) required for your routine is spent on the storage steps, not on the bitwise comparison itself.

Update 2: I misread the question, thinking that the comparison only included the last bit. As BrowserUK notes below, this is not correct. Apologies for the misunderstanding.

In reply to Re: Need a faster way to find matches by bobf
in thread Need a faster way to find matches by remzak

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.