my $arr = ['A -4 C','C -4 B','B -4 A','A -2 C','C -3 B'];
decomp_a2aoa_wth_idx($arr);

sub decomp_a2aoa_wth_idx
{
    my  $arr    = shift;
    my  @aoa    = ();

    foreach  ( 0 .. @{$arr}-1  )
    {
        my @tmp = split(" ", $arr->[$_]);
        push @tmp, $_;
        push @aoa,[@tmp];
    }

    return @aoa;
}