Here's the algorithm: 
use constant COL => 4;
my @data = qw( 10 15 25 30 10 13 );
my @cols = map [$_], @data;

while (@data > COL) {
  my $i = 0;
  my $s = $data[$i] + $data[$i+1];
  for my $j (1 .. @data-2) {
    ($i, $s) = ($j, $data[$j] + $data[$j+1])
      if $data[$j] + $data[$j+1] < $s;
  }
  splice @data, $i, 2, $s;
  splice @cols, $i, 2, [@{ $cols[$i] }, @{ $cols[$i+1] }];
}

[download]

_____________________________________________________
Jeff[japhy]Pinyan: Perl, regex, and perl hacker, who'd like a job (NYC-area)
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;

In reply to Re: Puzzle: need a more general algorithm by japhy
in thread Puzzle: need a more general algorithm by Ovid

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.