LaTeX-examples/tikz/red-black-tree/red-black-tree.tex

\documentclass{article}
\usepackage[pdftex,active,tightpage]{preview}
\setlength\PreviewBorder{2mm}
 
\usepackage{tikz}
\usetikzlibrary{trees,arrows,positioning, calc} 
\tikzstyle{redVertex}  =[draw,fill=red,     circle,minimum size=18pt,inner sep=0pt, text=white]
\tikzstyle{blackVertex}=[draw,fill=black,   circle,minimum size=18pt,inner sep=0pt, text=white]
\tikzstyle{nil}        =[draw,fill=black,rectangle,minimum size=18pt,inner sep=0pt, text=white]

\begin{document}
\begin{preview}
\begin{tikzpicture}[font=\sffamily,very thick,level/.style={sibling distance=80mm/#1}]
\node [blackVertex] (r){8}
  child {
    node [blackVertex] {3}
    child {
      node [redVertex] {2}
      child {
        node [blackVertex] {-3}
        child {
            node [redVertex] {-4}
            child {node [nil] {NIL}}
            child {node [nil] {NIL}}
        }
      } 
      child {
        node [blackVertex] {2}
        child {node [nil] {NIL}}
        child {node [nil] {NIL}}
      }
    }
    child {
      node [blackVertex] {6}
      child {
        node [redVertex] {5}
        child {node [nil] {NIL}}
        child {node [nil] {NIL}}
      }
      child {
        node [redVertex] {7}
        child {node [nil] {NIL}}
        child {node [nil] {NIL}}
      }
    }
  }
  child {
    node [blackVertex] {17}
    child {
      node [blackVertex] {9}
      child {
        node [redVertex] {11}
        child {node [nil] {NIL}}
        child {node [nil] {NIL}}
      }
    }
    child {
      node [redVertex] {19}
      child {
        node [blackVertex] {17}
        child {
          node [redVertex] {17}
          child {node [nil] {NIL}}
          child {node [nil] {NIL}}
        }
      }
      child {
        node [blackVertex] {20}
        child {node [nil] {NIL}}
        child {node [nil] {NIL}}
      }
    }
  };
\end{tikzpicture}
\end{preview}
\end{document}