BrowserUk,
I am likely misunderstanding the problem. For the sake of simplicity, I am using strings of 1 character. Do I have the correct output for the provided input? 
string 1: 0
string 2: 1
string 3: 0
string 4: 1
string 5: 0

1 & 2 -> 01 10
1 & 3 -> 00 00
1 & 4 -> 01 10
1 & 5 -> 00 00
2 & 3 -> 10 01
2 & 4 -> 11 11
2 & 5 -> 10 01
3 & 4 -> 01 10
3 & 5 -> 00 00
4 & 5 -> 10 01

Totals

01 = 6
10 = 6
11 = 2
00 = 6

[download]
If that is correct, then I think my math approach will work.

Cheers - L~R

In reply to Re^5: Speeding permutation counting by Limbic~Region
in thread Speeding permutation counting by albert

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.