To achieve your desire, it would be necessary to make some (as far as I could tell) major changes in the algorithmic package. One possibility is to use the algorithmicx package instead. A little example
\documentclass[]{scrbook}
\usepackage[T1]{fontenc}
\usepackage[english]{babel}
\usepackage{algorithm,algorithmicx,algpseudocode}
\usepackage{amssymb}
%\algrenewcommand{\algorithmiccomment}[1]{\hfill$\blacktriangleright$ #1}
\begin{document}
\begin{algorithm}
\caption{Influx}
\label{influx}
\begin{algorithmic}[1]
\Require $p \in [0,1]$, $G$
\Ensure None \Comment{a test comment}
\For{$i = 0 \to 2^d-1$}\Comment{another test comment}
\If{$n(\nu_i) = 0$}
\If{ $x < p$} \Comment{$x$ is a normal distribution number in the range of $[0,1]$}
\State Occupy $v_i$ site with probablility $p$
\EndIf
\EndIf
\EndFor
\end{algorithmic}
\end{algorithm}
\end{document}
Here's the result:
Uncommenting the line with \algrenewcommand you'll get a black triangle for the comments.
Is this what you are trying to achieve?
This is the MWE:
\documentclass{article}
\usepackage[plain]{algorithm}
\usepackage{algpascal}
\begin{document}
\algrenewcommand\textkeyword{\textrm}
\algdef{SE}{For}{End}[2]{%
\textkeyword{for} \(#1\) \textkeyword{to} \(#2\) \textkeyword{do begin}}{%
\textkeyword{end}}
\begin{algorithm}
\begin{algorithmic}[1]
\State Assign an ordering $A_{1}, ..., A_{n}$ to the nonterminals of the grammar.
\For{i = 1}{n}
\For{j = 1}{i-1}
\State for each production of the form $A_{i} \rightarrow A_{j} \alpha$
\End
\End
\end{algorithmic}
\caption{Paull's algorithm}
\end{algorithm}
\end{document}
Explanation
To match your first two requests, I've redefined the behavior of for to have an end statement by adding the lines:
\algdef{SE}{For}{End}[2]{%
\textkeyword{for} \(#1\) \textkeyword{to} \(#2\) \textkeyword{do begin}}{%
\textkeyword{end}}
To match your last request, it suffices to add the line:
\algrenewcommand\textkeyword{\textrm}
which redefines the font for keywords to be \textrm instead of \textbf.
In regards of your 3rd request, there are two ways.
If you want the algorithm to behave as an algorithm, simply load the algorithm package with the option plain as in the above MWE:
\usepackage[plain]{algorithm}
If you want the algorithm to behave as a figure, there is no need to load the algorithm package, simply insert the algorithmic environment inside a figure, i.e. replace the lines
\begin{algorithm}
\begin{algorithmic}[1]
...
\end{algorithmic}
\caption{Paull's algorithm}
\end{algorithm}
with
\begin{figure}
\begin{algorithmic}[1]
...
\end{algorithmic}
\caption{Paull's algorithm}
\end{figure}
and you will have
Addendum
This is the complete implementation of the algorithm in the figure:
\documentclass{article}
\usepackage[plain]{algorithm}
\usepackage{algpascal}
\begin{document}
\algrenewcommand\textkeyword{\textrm}
\algdef{SE}{For}{End}[2]{%
\textkeyword{for} \(#1\) \textkeyword{to} \(#2\) \textkeyword{do begin}}{%
\textkeyword{end}}
\algdef{SE}{ForEach}{End}[1]{%
\textkeyword{for each} #1 \textkeyword{do begin}}{%
\textkeyword{end}}
\begin{algorithm}
\begin{algorithmic}[1]
\State Assign an ordering $A_{1}, \dots, A_{n}$ to the nonterminals of the grammar.
\For{i := 1}{n}
\For{j := 1}{i-1}
\ForEach{production of the form $A_{i} \rightarrow A_{j} \alpha$}
\State remove $A_{i} \rightarrow A_{j} \alpha$ from the grammar
\ForEach{production of the form $A_{j} \rightarrow \beta$}
\State add $A_{i} \rightarrow \beta\alpha$ to the grammar
\End
\End
\End
\State transform the $A_{i}$-productions to eliminate direct left recursion
\End
\end{algorithmic}
\caption{Paull's algorithm}
\end{algorithm}
\end{document}
There is the need to define a new command \ForEach:
\algdef{SE}{ForEach}{End}[1]{%
\textkeyword{for each} #1 \textkeyword{do begin}}{%
\textkeyword{end}}
Note that I've defined \ForEach so to take one "text" argument, because it seemed to me the best way to define it.
If you want it to take a "math" argument, then define it as
\algdef{SE}{ForEach}{End}[1]{%
\textkeyword{for each} \(#1\) \textkeyword{do begin}}{%
\textkeyword{end}}
and use it as follows (amsmath is needed for the command \text):
\ForEach{\text{production of the form }A_{i} \rightarrow A_{j} \alpha}
Best Answer
You can use the following as a template-like approach to adjust components of your algorithm. The idea is to update the line numbering scheme (with a
\refprefix) to print in\alphrather than\arabic, and also indent to the appropriate depth so as to match the position (horizontally) in the original algorithm.If you don't want the horizontal rules, then just drop the
algorithmenvironment surrounding thealgorithmicenvironment. Hopefully it doesn't float elsewhere. If that happens, one could insert the horizontal rules manually, unless you have a different algorithm float style.