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;
print Dumper(\@a);
##</code><code>##

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