Change style of specific algorithm with algorithm2e

Question

I have the following LaTeX code

 \documentclass{article}
 \usepackage[ruled]{algorithm2e}
 \begin{document}

     \begin{algorithm}
        do something\;
     \caption{Algorithm #1}
     \end{algorithm}

     \begin{algorithm}
        do something\;
     \caption{Algorithm #2}
     \end{algorithm}

     \begin{algorithm}
        do something\;
     \caption{Algorithm #3}
     \end{algorithm}

 \end{document}

Given that I have initialised algorithm2e with the "ruled" option, the three algorithms appear with a nice ruled frame.

I want the second algorithm to appear with no frame at all, that is, just plain code. Is there a way to achieve this?

Thanks.

Answer 1

These options are set when loading the package and is meant to promote consistency. However, it's fairly trivial to adjust the algorithm style.

Below I've introduced \algorithmstyle{<style>} where you can specify/update the algorithm style to match any of the existing ones provided by the package:

\documentclass{article}
\usepackage[ruled]{algorithm2e}
\makeatletter
\newcommand{\algorithmstyle}[1]{\renewcommand{\algocf@style}{#1}}
\makeatother
\begin{document}

\begin{algorithm}
  do something\;
\caption{Algorithm A}
\end{algorithm}

\algorithmstyle{plain}
\begin{algorithm}
  do something\;
\caption{Algorithm B}
\end{algorithm}

\algorithmstyle{ruled}
\begin{algorithm}
  do something\;
\caption{Algorithm C}
\end{algorithm}

 \end{document}

Default style choices include plain, plainruled, boxed, ruled, algoruled, boxruled and tworuled.