documentclass[a4paper, twoside]{book}

usepackage{listings}
lstset{
    basicstyle=small,
    keywordstyle=ttfamily,
    identifierstyle=ttfamily,
    numbers=left,
    numberstyle=tiny,
    stepnumber=5,
    numbersep=5pt,
    numberfirstline=true,
    firstnumber=1,
    mathescape=true
    }


begin{document}

begin{lstlisting}
g = $infty$

for $v$ in vertices:
    s = $emptyset$
    r = ${v}$
    pred[v] = $emptyset$
    d[v] = $0$
    while not r == $emptyset$:
        x = $x in r$
        s = s $cup$ x
        r = r $setminus$ x
        for
end{lstlisting}

begin{lstlisting}
step = 1
res = new Graph()

def BFS(v,currentLength,maxLength):
    if currentLength < maxLength:
        if not label[v]:
            label[v] = step
            step = step + 1
        for w in Neighborhood(v):
            if label[w]:
                continue
            pred[w] = v
            res.Append(v,w)
            BFS(w,currentLength + 1, maxLength)

root = PickVertex()
BFS(root,0,k)
end{lstlisting}


end{document}