My 1 cent using XML::Rules (used as an exercise for myself). The xml is repaired by remiah. 
#!/usr/bin/perl
use strict;
use warnings;

use XML::Rules;

my $xml = <<'XML';
<all>
<doc>
<date name="processingtime">2011-04-09T11:12:22.049Z</date>
<str name="docuid">121422</str>
<str name="title">ABC</str>
</doc>
<doc>
<date name="processingtime">2012-04-09T11:12:22.049Z</date>
<str name="docuid">13427</str>
<str name="title">CDE</str>
</doc>
<doc>
<date name="processingtime">2010-04-09T11:12:22.049Z</date>
<str name="docuid">89822</str>
<str name="title">LKK</str>
</doc>
</all>
XML


my @rules = (
          'str' => 'as array',
          'date' => 'as is',
          'doc' => 'as array no content',
          'all' => 'no content'
);

my $parser = XML::Rules->new(rules => \@rules);
my $data = $parser->parse( $xml );

my $max_value = 0;

for my $chunk ( @{ $data->{all}{doc} } )
{
    for my $str ( @{ $chunk->{str} } )
    {
        $str->{name} eq 'docuid' 
                and $str->{_content} > $max_value 
                and $max_value = $str->{_content};
    }
}
print "The max value is: $max_value\n";

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In reply to Re: Finding max value from a unique tag from XML by vagabonding electron
in thread Finding max value from a unique tag from XML by Shaveta_Chawla

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