Drawing a linked list as a tree

Question

I'd like to draw this as a TikZ:

  \
   \
    +---+---+
    | * | * |
    +/--+---\
    /        \
   1          +---+---+
              | * | * |
              +/--+---\
              /        \
             2          +---+---+
                        | * | * |
                        +/--+---+
                        /
                       3

I've tried various things to make an "empty rectangle with a dividing line, to no avail. . . .

Answer 1

Here's a simple example to get you started:

\documentclass[tikz]{standalone}

\usepackage{tikz}
\usetikzlibrary{
  graphs,
  graphdrawing,
  shapes.multipart
}
\usegdlibrary{trees}

\tikzset{
  link/.style={
    rectangle split,
    rectangle split horizontal,
    rectangle split parts=2,
    draw,
    /tikz/graphs/as={\nodepart{two} \footnotesize\texttt{*ptr}},
  }
}

\begin{document}
\tikz \graph [tree layout] {
  head [draw, as=\emph{head}] -- {
     link1 [link] -- {
       1, 
       link2 [link] -- {
         2, 
         link3 [link] -- {
           3, 
           link4 [link]
         }
       }
     }
  }
};
\end{document}