\documentclass{article}

\usepackage{weiwBTree}

\begin{document}

An initial $B^+$-tree.

\begin{center}
  \scalebox{.7}{
    \begin{tikzpicture}
      \btreeinodefour{root}{13}{17}{24}{30};
      \xyshift{-40mm}{-20mm}{\btreelnodefour{n1}{2}{3}{5}{7}}
      \xyshift{0mm}{-20mm}{\btreelnodefour{n2}{14}{16}{}{}}
      \xyshift{40mm}{-20mm}{\btreelnodefour{n3}{19}{20}{22}{}}
      \xyshift{80mm}{-20mm}{\btreelnodefour{n4}{24}{27}{29}{}}
      \xyshift{120mm}{-20mm}{\btreelnodefour{n5}{33}{34}{38}{39}}
      % 
      \foreach \x in {1,2,...,5} { \btreelink{root-\x}{n\x} }
    \end{tikzpicture}
  }
\end{center}


After inserting 40.
\begin{center}
  \scalebox{.7}{
    \begin{tikzpicture}
      % 
      \btreeinodefour{root}{24}{}{}{};
      \xyshift{-40mm}{-20mm}{\btreeinodefour{n1}{13}{17}{}{}}
      \xyshift{80mm}{-20mm}{\btreeinodefour{n2}{30}{38}{}{}}
      % 
      \xyshift{-80mm}{-40mm}{\btreelnodefour{n11}{2}{3}{5}{7}}
      \xyshift{-40mm}{-40mm}{\btreelnodefour{n12}{14}{16}{}{}}
      \xyshift{0mm}{-40mm}{\btreelnodefour{n13}{19}{20}{22}{}}
      \xyshift{40mm}{-40mm}{\btreelnodefour{n21}{24}{27}{29}{}}
      \xyshift{80mm}{-40mm}{\btreelnodefour{n22}{33}{34}{}{}}
      \xyshift{120mm}{-40mm}{\btreelnodefour{n23}{38}{39}{40}{}}
      % 
      \foreach \x in {1,2} { \btreelink{root-\x}{n\x} }
      \foreach \x in {1,2,3} { \btreelink{n1-\x}{n1\x} }
      \foreach \x in {1,2,3} { \btreelink{n2-\x}{n2\x} }
    \end{tikzpicture}
  }
\end{center}

Yet another example.
\begin{center}
  \scalebox{0.7}{
    \tikzstyle{connlink} = [draw, ->, >=stealth', dashed]
    \begin{tikzpicture}
      % 
      \btreeinodefour{root}{10}{20}{30}{80};
      \xyshift{-80mm}{-10mm}{\btreetriangle{n1}{A}}
      \xyshift{-70mm}{-15mm}{\btreetriangle{n2}{B}}
      \xyshift{-60mm}{-20mm}{\btreetriangle{n3}{C}}
      \xyshift{-10mm}{-20mm}{\btreeinodefour{n4}{35}{42}{50}{65}}
      \xyshift{ 50mm}{-20mm}{\btreeinodefour{n5}{90}{98}{}{}}
      % 
      \xyshift{-40mm}{-30mm}{\btreelnodefour{n41}{30}{31}{}{}}
      \xyshift{-30mm}{-40mm}{\btreelnodefour{n42}{36}{38}{}{}}
      \xyshift{-20mm}{-50mm}{\btreelnodefour{n43}{42}{43}{}{}}
      \xyshift{10mm}{-40mm}{\btreelnodefour{n44}{51}{52}{56}{60}}
      \xyshift{20mm}{-30mm}{\btreelnodefour{n45}{68}{69}{70}{79}}
      % 
      \xyshift{45mm}{-50mm}{\btreelnodefour{n51}{81}{82}{}{}}
      \xyshift{55mm}{-40mm}{\btreelnodefour{n52}{94}{95}{96}{97}}
      \xyshift{65mm}{-30mm}{\btreelnodefour{n53}{98}{99}{100}{105}}
      % 
      \foreach \x in {1,2,...,3} { \btreelinknorth{root-\x}{n\x} }
      \foreach \x in {4,5} { \btreelink{root-\x}{n\x} }
      \foreach \x in {1,2,...,5} { \btreelink{n4-\x}{n4\x} }
      \foreach \x in {1,2,...,3} { \btreelink{n5-\x}{n5\x} }
      % annotations
      \node at (root.north east) {$I_1$};
      \node at (n4.north east) {$I_2$};
      \node at (n5.north east) {$I_3$};
      % 
      \node at ([xshift=-10pt] n41.west) {$L_1$};
      \node at ([xshift=-10pt] n42.west) {$L_2$};
      \node at ([xshift=-10pt] n43.west) {$L_3$};
      \node at ([xshift=10pt,yshift=5pt] n44.north west) {$L_4$};
      \node at ([xshift=10pt,yshift=5pt] n45.north west) {$L_5$};
      \node at ([xshift=10pt,yshift=5pt] n51.north west) {$L_6$};
      \node at ([xshift=10pt,yshift=5pt] n52.north west) {$L_7$};
      \node at ([xshift=10pt,yshift=5pt] n53.north west) {$L_8$};
    \end{tikzpicture}
  }
\end{center}


\end{document}


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