use strict;
use warnings;

use Data::Dumper;

my @arr;
push @arr
   , ( q{A} .. q{Z}, q{0} .. q{9} )[ int rand 36 ]
   . sprintf( q{%04d}, int rand 10000 )
   for 1 .. 25;

print Data::Dumper
   ->Dumpxs( [ \ @arr ], [ qw{ *arr } ] );

my %letters = ();
foreach my $letter ( q{A} .. q{Z} )
{
    last unless @arr;
    my $rxLetter = qr{$letter};
    foreach my $idx ( reverse 0 .. $#arr )
    {
        next unless $arr[ $idx ] =~ $rxLetter;
        push @{ $letters{ $letter } }, splice @arr, $idx, 1;
    }
}

print Data::Dumper
   ->new( [ \ %letters, \ @arr ], [ qw{ *letters *arr } ] )
   ->Sortkeys( 1 )
   ->Dumpxs();

##</code><code>##

@arr = (
         'V1348',
         'O5896',
         'Q3648',
         '18290',
         'J6417',
         'G5924',
         '46458',
         'O1853',
         'T3800',
         'X2826',
         'G0512',
         'K7895',
         'X1951',
         'C7754',
         'S7722',
         'P8593',
         'K7636',
         'F6980',
         'U0711',
         'E9196',
         'C9297',
         'O8023',
         'T2141',
         '67437',
         'K8979'
       );
%letters = (
             'C' => [
                      'C9297',
                      'C7754'
                    ],
             'E' => [
                      'E9196'
                    ],
             'F' => [
                      'F6980'
                    ],
             'G' => [
                      'G0512',
                      'G5924'
                    ],
             'J' => [
                      'J6417'
                    ],
             'K' => [
                      'K8979',
                      'K7636',
                      'K7895'
                    ],
             'O' => [
                      'O8023',
                      'O1853',
                      'O5896'
                    ],
             'P' => [
                      'P8593'
                    ],
             'Q' => [
                      'Q3648'
                    ],
             'S' => [
                      'S7722'
                    ],
             'T' => [
                      'T2141',
                      'T3800'
                    ],
             'U' => [
                      'U0711'
                    ],
             'V' => [
                      'V1348'
                    ],
             'X' => [
                      'X1951',
                      'X2826'
                    ]
           );
@arr = (
         '18290',
         '46458',
         '67437'
       );