How is this kind of pseudocode written in latex?

Question

It doesn't seem to be formatted using instructions from the usual algorithm libraries of Latex.

It seems to be simply formatted text, I am uncertain.

Answer 1

A simple way to do this is to use the enumitem package to make nested lists. The trick of starting the list on a new line is adapted from this answer. This is not needed if every item contains some text, but is necessary if a step is embedded directly as an item of the list. If a step will never be embedded like this, then the before={\apptocmd{\item}{\mbox{}}{}{}} code is not required.

\documentclass{article}
\usepackage{enumitem}
\usepackage{etoolbox}
\newlist{algolist}{enumerate}{3}
\setlist*[algolist]{leftmargin=*,before={\apptocmd{\item}{\mbox{}}{}{}}}
\setlist*[algolist,1]{label={\itshape Step \arabic*:}}
\setlist*[algolist,2]{label={\itshape Step \arabic{algolisti}.\arabic*:}}
\setlist*[algolist,3]{label={\itshape Step \arabic{algolisti}.\arabic{algolistii}.\arabic*:}}
\begin{document}
\begin{algolist}
\item This is the first step of the algorithm. It can have many lines in it and they will wrap as you would expect. 
\item This is the second step of the algorithm.
    \begin{algolist}
    \item This is the first substep of the second step of the algorithm.
    \item This is the second substep of the second step of the algorithm.
        \begin{algolist}
        \item This is the first substep of the second substep of the algorithm.
        \item This is the second substep of the second substep of the algorithm.
        \end{algolist}
    \end{algolist}
\end{algolist}
\end{document}