If this is the case, then we do this:

use Data::Dumper;
use strict;
use warnings;

my $arr = ['A -4 C','C -4 B','B -4 A','A -2 C','C -3 B'];
my @a = map {[split " ", $arr->[$_] . " $_"]} (0 .. @$arr - 1);
print Dumper(\@a);
[download]

Which gives:

$VAR1 = [
          [
            'A',
            '-4',
            'C',
            '0'
          ],
          [
            'C',
            '-4',
            'B',
            '1'
          ],
          [
            'B',
            '-4',
            'A',
            '2'
          ],
          [
            'A',
            '-2',
            'C',
            '3'
          ],
          [
            'C',
            '-3',
            'B',
            '4'
          ]
        ];
[download]