Side-by-side algorithms in two columns paper

Question

I am trying to put two algorithms side-by-side on a page so it is easy to compare their differences. I am using the acm template, algorithm2e package and minipage environment. but I get this error:

! LaTeX Error: [H] in two columns mode is not allowed for algorithms.  

I have followed these steps in this post, but it dose not work out for me. multiple algorithm2e algorithms in two column documents

Does anyone know how I can put two algorithms side-by-side?

---

This is my sample code it us work fine in one column page but it does not work in two column page.

\begin{minipage}[t]{8cm} 

  \null 
  \begin{algorithm}[H]
    % \caption{Algo 1}

    \SetKwData{Left}{left}\SetKwData{This}{this}\SetKwData{Up}{up}
    \SetKwFunction{Union}{Union}\SetKwFunction{FindCompress}{FindCompress}
    \SetKwInOut{Input}{Generation step}\SetKwInOut{Output}{Initialization step}
    \Input{\color{blue} Generate } 
    \Output{ $K$}
    \BlankLine
    \Output{\color{blue}***,**}

    \emph{\bf{\color{blue} 444}}\;
    \emph{\color{blue} 2222}\;
    \emph{\color{blue}11111\;} 
    \emph{\color{blue}111\;}
    \emph{###\;
    }
    \BlankLine
    \emph{\bf{\color{blue} Received $ID$}}\;
    \For{\color {blue} each node that receives a ID}{
      \If{\color {blue} ##}{\color {blue} Add value to the list
      }
      \BlankLine
      \For{Each $received  ID$}{
        Find *,$s$\;
        \eIf{$s$ $>$ ID$}{do nothing}{Replace #}
      }
    }
    \BlankLine
    Find the smallest element on the list, $s$\;
    \eIf{$s$ $=$ $0$}{###}{*** }\BlankLine
    \BlankLine
    \caption{DNE Algorithm}\label{DNE Algorithm}
  \end{algorithm}

\end{minipage}%
\removelatexerror
\begin{minipage}[t]{8cm}
  \null

  \begin{algorithm}[H]

    \emph{**}\;
    % \Output{***}
    \emph{**}\;
    \emph{** size to 1}\;
    \BlankLine
    \emph{\bf{Broadcast}}\;
    \emph{broadcast it}\;
    \BlankLine
    \emph{\bf{Estimation}}\;
    \For{each ID$}{
      Find the smallest ,$s$\;
      \eIf{$s$ $>$ $received ID$}{do nothing}{Replace $s$ }
    }
    \BlankLine
    Find the smallest element on the list, $s$\;
    \eIf{$s$ $=$ $0$}{1111}{ab}\BlankLine
    \caption{Algorithm}\label{DNE-Algorithm}

  \end{algorithm}
\end{minipage}

Answer 1

Package algorithm2e does not allow H in twocolumn mode, regardless if single or double float. A little excerpt from the package file:

\if@twocolumn\@latex@error{[H] in two columns mode is not allowed for algorithms}\fi% TODO: SCREAM if H in two colums!

Bad thing is, for some reason two captions in an algorithm environment don't work. The solution can be a quick hack, using a figure and mimicking and algorithm. You have to be very careful with the order of your algorithms that way. There is a pretty high chance, that the numbering gets messed up.
There might be a much better and cleaner solution.

\documentclass[twocolumn
]{article}
\usepackage{blindtext}
\usepackage{algorithm2e}
\begin{document}
\blindtext[5]
\begin{algorithm*}%[H]
    \begin{minipage}{0.45\textwidth}
        \rule{\linewidth}{2cm}
        \caption{left side of a pretty pretty long long
        long very very long caption}
    \end{minipage}\hfill
    \begin{minipage}{0.45\textwidth}
        \rule{\linewidth}{4cm}
        \caption{right side of a pretty pretty long long
        long very very long caption}
    \end{minipage}
\end{algorithm*}

\blindtext
\begin{figure*}
    \makeatletter
    \def\@captype{algocf}
    \makeatother
    \begin{minipage}{0.45\textwidth}
        \rule{.5\linewidth}{2cm}
        \caption{left side of a pretty pretty long long
        long very very long caption}
    \end{minipage}\hfill
    \begin{minipage}{0.45\textwidth}
        \rule{\linewidth}{4cm}
        \caption{right side}
    \end{minipage}
\end{figure*}
\blindtext[5]
\end{document}