Fig2

% Figure 2 Source Code | China Papers | Algorithm | Data structures | Vu Van Dung 2019
%
% Command line compilation:
% pdflatex -jobname=output main.tex
% convert -density 130 -background white -flatten output.pdf pages.png
\documentclass[tikz]{standalone}
\usepackage[utf8]{inputenc}
\usepackage[T1,T5]{fontenc}
\usepackage{inconsolata}
\usepackage{mathptmx}
\begin{document}
\fontencoding{T1}\selectfont
\begin{tikzpicture}[>=stealth]
    \node[draw,inner sep=0pt,minimum size=.5cm] (0) at (0,0) {\texttt{C}};
    \foreach \i [count=\j] in {D,A,C,B,D,C,A,D,C,D,B,A,D,C,C,B,A,D} {
        \pgfmathtruncatemacro{\before}{\j-1}
        \node[draw,inner sep=0pt,minimum size=.5cm,right]
            (\j) at (\before.east) {\texttt{\i}};
    }
    \draw[densely dotted] (0.north west) -- ++ (-.3,0) (0.south west) -- ++ (-.3,0);
    \draw[densely dotted] (18.north east) -- ++ (.3,0) (18.south east) -- ++ (.3,0);
    \draw (0.north west) -- (18.north east) (0.south west) -- (18.south east);
    \foreach \i in {15,13,12,11}
        \draw[->] (16.north) parabola[parabola height=.5cm] (\i.north);
    \foreach \i in {14,13,12,11}
        \draw[->] (15.south) parabola[parabola height=-.5cm] (\i.south);
\end{tikzpicture}
\end{document}