# How to format a pseudocode algorithm

I would like to know how to format a pseudocode algorithm like the one shown in the picture below. I would like to see an example of Tex/Latex code that would mimic the style, formatting and design of the pseudocode illustrated on this picture. I know how to write simple pseudocode algorithms, but i don't know how to

1. Align the pseudocode with an \item "Some text.."
2. How to write a pseudocode with Input and Output exactly below the procedure/function so that they are not numbered and aligned with procedure/function
3. How to use the block braces in form of "vertical lines"

My attempt

\documentclass[a4paper]{article}

\usepackage[english]{babel}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{graphicx}
\usepackage[colorinlistoftodos]{todonotes}
\usepackage{algorithm}
\usepackage{algpseudocode}

\usepackage{geometry}
\geometry{
a4paper,
total={210mm,297mm},
left=20mm,
right=20mm,
top=20mm,
bottom=20mm,
}

\begin{document}
\begin{enumerate}

\item Some text goes here . . .
\begin{algorithm}
\caption{Merge Sort}
\begin{algorithmic}[1]
\Function{Merge}{$A,p,q,r$}\Comment{Where A - array, p - left, q - middle, r - right}

\State ${n_1} = q - p + 1$
\State ${n_2} = r - q$
\State Let $L[1 \ldots {n_1} + 1]$ and $R[1 \ldots {n_2} + 1]$ be new arrays
\For{$i = 1$ to ${n_1}$}
\State $L[i] = A[p + i - 1]$
\EndFor
\For{$j = 1$ to ${n_2}$}
\State $R[i] = A[q + j]$
\EndFor
\State $L[{n_1} + 1] = \infty$
\State $R[{n_2} + 1] = \infty$
\State $i = 1$
\State $j = 1$
\For{$k = p$ to $r$}
\If {$L[i] < R[j]$}
\State $A[k] = L[i]$
\State $i = i + 1$
\ElsIf {$L[i] > R[j]$}
\State $A[k] = R[j]$
\State $j = j + 1$
\Else
\State $A[k] = - \infty$ \Comment{We mark the duplicates with the largest negative integer}
\State $j = j + 1$
\EndIf
\EndFor
\EndFunction

\end{algorithmic}
\end{algorithm}
\end{enumerate}
\end{document}


My result

1. As you can see i don't know how to align the algorithm with the itemized text.
2. I don't know how to place Input and Output words below the function, so that they are not numbered and aligned with a function.
3. I like more the style of vertical line block, rather than just condition:end.

I'm new to writing pseudocode algorithms with Latex, but i suspect the style and formatting i'm looking for is in the package algorithm2e. Can someone show me how to achieve the following result:

I want to learn to write pseudocode algorithm in the same style as in the picture above.

• I want to get the exact style as on the picture. For example, how can i write "Input" and "Output" below the function. In other words i want to see the Latex code that will mimic the style, design and formatting of the pseudocode illustrated on the picture. Oct 5, 2014 at 2:51
• @user_777: How about, as a starting point, show us some effort from your end via a minimal working example (MWE). Start by looking into the algorithm2e package.
– Werner
Oct 5, 2014 at 4:48
• @Werner Updated my post and showed my efforts... Oct 6, 2014 at 8:23

Here it is:

Code:

\documentclass{article}
\usepackage{amsmath}
\usepackage[linesnumbered,ruled]{algorithm2e}

\begin{document}
\begin{algorithm}
\SetKwInOut{Input}{Input}
\SetKwInOut{Output}{Output}

\underline{function Euclid} $(a,b)$\;
\Input{Two nonnegative integers $a$ and $b$}
\Output{$\gcd(a,b)$}
\eIf{$b=0$}
{
return $a$\;
}
{
return Euclid$(b,a\mod b)$\;
}
\caption{Euclid's algorithm for finding the greatest common divisor of two nonnegative integers}
\end{algorithm}
\end{document}