Modifying style of chapters

Question

I am trying to write a book in latex so I have the following chapter style in my latex code:

How can this code be modified to get the following chapter style?

\documentclass[twoside,a4paper,cleardoublepage=empty,14pt]{book}
                 

\begin{document}

\tableofcontents

\chapter{Analysis of Algorithms}    

  
\end{document}

Answer 1

Something like this?

\documentclass{book}
\usepackage{tikz}
\usepackage{titlesec}
\usepackage{lipsum}
\makeatletter
\newcommand*{\@chaptercolor}{red!50}
\newcommand*{\chaptercolor}[1]{%
    \renewcommand*{\@chaptercolor}{#1}%
}
\titleformat{\chapter}{\sffamily\bfseries\Large}{%
    \smash{%
        \begin{tikzpicture}[baseline=0]
            \useasboundingbox (-1,-1) rectangle (1,1);
            \draw[white, line width=4pt, fill=\@chaptercolor] (-1,-1) rectangle (1,1);
            \draw (-1,-1) rectangle (1,1);
            \node at (0,0) {\Huge\thechapter};
            \node at (0,1.3) {Chapter};
            \draw[overlay, line width=.2pt] (1.1,0) -- (\dimexpr\linewidth-1cm,0);
        \end{tikzpicture}%
    }%
}{0mm}{\newline\hspace*{2mm}}
\makeatother
\begin{document}
\chapter{Analysis of Algorithms}

\lipsum[1]

\chaptercolor{blue!50}
\chapter{Another chapter}

\lipsum[2]
\end{document}

You can change the color of the box to any color that is understood by TikZ with \chaptercolor{<color>}. For example, the above code also outputs the following.

The new color will stay the same until you change it again.