LeetCode 58. Length of Last Word (LaTeX)

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{datetime2}
\usepackage{expl3}

\begin{document}
\setlength{\parindent}{0cm}

\ExplSyntaxOn

\int_new:N \result
\str_new:N \g_tmpc_str

\cs_set:Npn \get_catcode:n #1 {
    \char_value_catcode:n { `#1 }
}

\cs_set:Npn \longest_last_word:n #1 {
    \str_gset:Nn \g_tmpa_str {#1}
    \par raw~input:~\str_use:N \g_tmpa_str \ (length:~\str_count:N \g_tmpa_str)
    % reverse the string, for convenience
    \tl_reverse:N \g_tmpa_str
    % trim spaces
    \str_gset:Nx \g_tmpb_str {\exp_args:NV \tl_trim_spaces:n \g_tmpa_str}
    % convert to string
    \par reversed~trimmed~input:~\str_use:N \g_tmpb_str \ (length:~\str_count:N \g_tmpb_str)
    \int_gset:Nn \result {0} % set result variable
    \str_if_empty:NTF {\g_tmpb_str} { }
        {
        \bool_gset:Nn \g_tmpa_bool \c_true_bool % loop variable
        \bool_do_while:Nn \g_tmpa_bool
            {
            \str_if_empty:NTF \g_tmpb_str
                {
                % exit loop if nothing is left
                \bool_gset:Nn \g_tmpa_bool \c_false_bool
                }
                {
                % get the head of string
                \str_gset:Nx \g_tmpc_str {\str_head:N \g_tmpb_str}
                % get catcode of string
                \exp_args:NNx \int_gset:Nn \g_tmpa_int { \exp_args:NV \get_catcode:n {\g_tmpc_str} }
                \par head: \g_tmpc_str \ (catcode~\int_use:N \g_tmpa_int)

                % check if head is space by comparing catcode
                \bool_if:nTF { \int_compare_p:nNn {\g_tmpa_int} {=} {10} ||
                                \int_compare_p:nNn {\g_tmpa_int} {=} {12} }
                    {% if head is space, exit loop
                    \bool_gset:Nn \g_tmpa_bool \c_false_bool
                    }
                    {% if it is not a space, increment counter
                    \int_gincr:N \result
                    % discard the head
                    \exp_args:NNx \str_gset:Nn \g_tmpa_str {\str_tail:N \g_tmpb_str}
                    \exp_args:NNV \str_gset:Nn \g_tmpb_str \g_tmpa_str
                    }
                }
            }

        }
}

\newcommand{\llw}[1]{\longest_last_word:n {#1}}

\ExplSyntaxOff


\llw{hello world}
\par \textbf{result: \the\result}
\llw{worlda}
\par \textbf{result: \the\result}
\llw{ }
\par \textbf{result: \the\result}
\llw{there is something special }
\par \textbf{result: \the\result}

\DTMnow

\end{document}