A red-black tree is a special type of binary tree, used in computer science to organize pieces of comparable data, such as text fragments or numbers. (Wikipedia)

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% Red-black tree% Author: Madit\documentclass{article}\usepackage{tikz}\usepackage[active,tightpage]{preview}\PreviewEnvironment{tikzpicture}\setlength{\PreviewBorder}{10pt}%\usetikzlibrary{arrows}\tikzset{treenode/.style = {align=center, inner sep=0pt, text centered,font=\sffamily},arn_n/.style = {treenode, circle, white, font=\sffamily\bfseries, draw=black,fill=black, text width=1.5em},% arbre rouge noir, noeud noirarn_r/.style = {treenode, circle, red, draw=red,text width=1.5em, very thick},% arbre rouge noir, noeud rougearn_x/.style = {treenode, rectangle, draw=black,minimum width=0.5em, minimum height=0.5em}% arbre rouge noir, nil}\begin{document}\begin{tikzpicture}[->,>=stealth',level/.style={sibling distance = 5cm/#1,level distance = 1.5cm}]\node [arn_n] {33}child{ node [arn_r] {15}child{ node [arn_n] {10}child{ node [arn_r] {5} edge from parent node[above left]{$x$}} %for a named pointerchild{ node [arn_x] {}}}child{ node [arn_n] {20}child{ node [arn_r] {18}}child{ node [arn_x] {}}}}child{ node [arn_r] {47}child{ node [arn_n] {38}child{ node [arn_r] {36}}child{ node [arn_r] {39}}}child{ node [arn_n] {51}
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