The other solutions are nice, but if you want a more efficient algorithm then it is indeed possible to avoid the sort. An O(N) algorithm is: 
#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my %hash = (
        Matt => 24, Dana => 19, Eric => 28, Sara => 20, John => 17, Mi
+ke => 23,
);

if (%hash)
{
        my (@min, @max);

        while( my ($k,$v) = each %hash )
        {
                @min = ($k,$v) unless @min && ($v > $min[1]);
                @max = ($k,$v) unless @max && ($v < $max[1]);
        }

        $hash{$min[0]} = $max[1];
        $hash{$max[0]} = $min[1];
}

print Dumper \%hash;

[download]
--Dave

In reply to Re: Interchanging hash values by dpuu
in thread Interchanging hash values by mjab

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.