use strict;
use warnings;

use Test::More tests => 2;
use List::MoreUtils 'part';

my ($C, $R) = (4, 3);
my @list = 1..12;

my $i = 0;
my @AoA = part { int ($i++ / $C) } @list;

is_deeply \@AoA, [[1 .. 4], [5 .. 8], [9 .. 12]];
is_deeply \@list, [1..12];