@a = qw/1 1 0 3 8 9 5 2 0 12 2 1/;
$m = 5;
print "@a\n";
for $x (0 .. $#a){
	if($a[$x] < $m){$a[$x+1] += $a[$x]; next;}
	if($a[$x+1] < $m and $x < $#a){$a[$x+1] += $a[$x]; next;}
	push @b, $a[$x];
}

print "@b\n";

##</code><code>##

1 1 0 3 8 9 5 2 0 12 2 1
5 8 9 7 15

##</code><code>##

@a = qw/1 13 0 3 8 9 5 2 2 0 1 0 2 0 2 1 13 1/;
$m = 5;
grep $s += $_, @a;
while ($s > $m){
	$e = shift @a;
	if($e >= $m){
		$s -= $e; push @b, $e;
	} else { $a[0] += $e;}
}

$s < $m ? $b[$#b] += $s : push @b, $s;
print "@b\n";