Below example will draw a tree with tikz. but if the tree has only left or right branch, it will be drawed vertically so we don't know if it's left or right branch.
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric,arrows,fit,matrix,positioning}
\pagestyle{empty} % do not remove
% The settings below are copied from fullpage.sty
\setlength{\textwidth}{\paperwidth}
\addtolength{\textwidth}{-3cm}
\setlength{\oddsidemargin}{1.5cm}
\addtolength{\oddsidemargin}{-2.54cm}
\setlength{\evensidemargin}{\oddsidemargin}
\setlength{\textheight}{\paperheight}
\addtolength{\textheight}{-\headheight}
\addtolength{\textheight}{-\headsep}
\addtolength{\textheight}{-\footskip}
\addtolength{\textheight}{-3cm}
\setlength{\topmargin}{1.5cm}
\addtolength{\topmargin}{-2.54cm}
\usepackage[active, tightpage]{preview}
\begin{document}
\begin{preview}
\tikzset{
treenode/.style = {circle, draw=black, align=center,
minimum size=1cm, anchor=center},
}
\begin{tikzpicture}[->,>=stealth',level/.style={sibling distance = 5cm/#1,
level distance = 1.5cm},scale=0.6, transform shape]
\node [treenode] {1}
child {
node [treenode] {2}
child {
node [treenode] {3}
child {
node [treenode] {4}
}
child {
node [treenode] {5}
}
}
child [child anchor=north] {
node [treenode] {6}
}
}
child [child anchor=north] {
node [treenode] {7}
child [child anchor=north] {
node [treenode] {8}
}
};
\end{tikzpicture}
\end{preview}
\end{document
The output:
In this example, how can we make node "8" as a left branch?
