最长公共前缀字符串

$arrs = array(
        "0" => "flower",
        "1" => "flow",
        "2" => "flight",
    );
    var_dump(longestCommonPrefix($arrs));

    function longestCommonPrefix($strs) {
        $count = count($strs);
        if ( $count == 0) {
            return "";
        }
        if ($count == 1) {
            return $strs[0];
        }

        $first = $strs[0];
        $len = strlen($first);

        $arr_count = count($strs);
        
        $public = "";

        for ($i = 0; $i < $len; $i++) {
            for($j = 1; $j < $arr_count; $j ++) {
                if (!isset($strs[$j][$i]) ||  $strs[$j][$i] != $first[$i]) {
                    return $public;
                }
            }
            $public .= $first[$i];
        }
        return $public;

    }