Add line breaks to specific lines only

function nl2pX($string) {
        $paragraphs = "";
        $pattern = array('<div class="row">', '<div>', '</div>', '<h1>', '</h1>', '<h2>', '</h2>', '<h3>', '</h3>', '<h4>', '</h4>', '<strong>', '</strong>', '<table class="center">', '<table>', '</table>', '<th>', '</th>', '<tr>', '</tr>', '<td>', '</td>', '<pre>', '</pre>', '<script>', '</script>', '<link>', '<code>', '</code>' );

        foreach (explode("\n", $string) as $line) {
                if (trim($line)) {
                        $match = (str_replace($pattern, '', $line) != $line);
                                if ($match == "1") {
                                        $paragraphs .= "{$line}\n";
                                } else {
                                $paragraphs .= "{$line}<br>\n";
                                }
                        }
                }
        return $paragraphs;
}