brackets

function solution($S) {
    $len = strlen($S);
    if(!$len){
        return 0;
    }

    $data = str_split($S, 1);
    $datasize = count($data) + 1;
    $chunked = array_chunk($data, $datasize / 2);

    $chunkedl[] = $chunked[0];
    $l = array_reduce($chunkedl, function ($total, $entry) {
        $rmatches  = preg_grep('/^(\(+)$/', $entry);
        return $total += $rmatches ? count($rmatches) : 0;
    });

    $chunkedr[] = $chunked[1];
    $r = array_reduce($chunkedr, function ($total, $entry) {
        $lmatches  = preg_grep('/^(\)+)$/', $entry);
        return $total += $lmatches ? count($lmatches) : 0;
    });

    if($r > $l){
        return $l;
    } elseif($r < $l) {
        return $r;
    }
    return $r;

}

var_dump(
    solution("((())  )(())")
);