Help on drawing a tree in latex

Question

I am trying to draw a diagram as given below in latex. I have little information about TikZ package? Is there any simple way to draw this diagram in latex?

I would be grateful if you could help on this matter.

Answer 1

% arara: pdflatex

\documentclass{article}
\usepackage{forest}

\begin{document}    
\begin{forest} for tree={%
        draw=gray, minimum width=1cm, minimum height=.5cm, rounded corners=3,
        text height=1.5ex, text depth=0ex,
        grow=east,reversed,
        edge={gray},
        parent anchor=east,
        child anchor=west,
        if n children=0{tier=last}{}
    }
[A
    [b 
        [l]]
    [c 
        [e[m]][f[n]][g[o]][h[p]]]
    [d
        [j[r]][k[s]]]
]
\end{forest}
\end{document}

Answer 2

In case you would like something slightly fancier, here is a variation on LaRiFaRi's answer:

\documentclass[tikz,border=10pt,multi]{standalone}
\usepackage{forest}
\usetikzlibrary{shadows}

\begin{document}
\tikzset{
  my node/.style={
    draw=gray,
    inner color=gray!5,
    outer color=gray!10,
    thick,
    minimum width=1cm,
    rounded corners=3,
    text height=1.5ex,
    text depth=0ex,
    font=\sffamily,
    drop shadow,
  }
}
\begin{forest}
  for tree={%
    my node,
    l sep+=5pt,
    grow'=east,
    edge={gray, thick},
    parent anchor=east,
    child anchor=west,
    if n children=0{tier=last}{},
    edge path={
      \noexpand\path [draw, \forestoption{edge}] (!u.parent anchor) -- +(10pt,0) |- (.child anchor)\forestoption{edge label};
    },
    if={isodd(n_children())}{
      for children={
        if={equal(n,(n_children("!u")+1)/2)}{calign with current}{}
      }
    }{}
  }
  [A
    [b
      [l]]
    [c
      [e[m]][f[n]][g[o]][h[p]]]
    [d
      [j[r]][k[s]]]
  ]
\end{forest}
\end{document}

Just for fun, here's a version which shows that forest doesn't use the same alphabet as the rest of us ;)...

\newcounter{mynode}
\setcounter{mynode}{0}
\begin{forest}
  for tree={%
    my node,
    l sep+=5pt,
    grow'=east,
    edge={gray, thick},
    parent anchor=east,
    child anchor=west,
    if n children=0{tier=last}{},
    edge path={
      \noexpand\path [draw, \forestoption{edge}] (!u.parent anchor) -- +(10pt,0) |- (.child anchor)\forestoption{edge label};
    },
    if={isodd(n_children())}{
      for children={
        if={equal(n,(n_children("!u")+1)/2)}{calign with current}{}
      }
    }{},
    delay={content={\stepcounter{mynode}\alph{mynode}}}
  },
  [
    [
      []]
    [
      [[]][[]][[]][[]]]
    [
      [[]][[]]]
  ]
\end{forest}

Or, if you wanted a splash of colour, you could try this code:

\documentclass[tikz,border=10pt,multi]{standalone}
\usepackage{forest}
\usetikzlibrary{shadows}
% xcolor manual: 34
\definecolorseries{colours}{hsb}{grad}[hsb]{.575,1,1}{.987,-.234,0}
\resetcolorseries[12]{colours}

\begin{document}
\tikzset{
  my node/.style={
    draw=gray,
    inner color=gray!5,
    outer color=gray!10,
    thick,
    minimum width=12mm,
    rounded corners=3,
    text height=1.5ex,
    text depth=0ex,
    font=\sffamily,
    drop shadow,
    minimum height=6mm,
  }
}
\forestset{
  my tree/.style={
      my node,
      l sep+=5pt,
      grow'=east,
      edge={gray, thick},
      parent anchor=east,
      child anchor=west,
      edge path={
        \noexpand\path [draw, \forestoption{edge}] (!u.parent anchor) -- +(10pt,0) |- (.child anchor)\forestoption{edge label};
      },
      if={isodd(n_children())}{
        for children={
          if={equal(n,(n_children("!u")+1)/2)}{calign with current}{}
        }
      }{},
  }
}
\newcounter{mynode}
\setcounter{mynode}{0}
\begin{forest}
  for tree={
    my tree
  },
  before typesetting nodes={
    for tree={
      my tree,
      content={\color{colours!!+}\stepcounter{mynode}\alph{mynode}},
      font=\bfseries\sffamily,
    }
  },
  before packing={
    for tree={
      if n children=0{tier=last}{},
    }
  }
  [
    [[]]
    [, delay={repeat=4{append={[[]]}}}
    ]
    [, delay={repeat=2{append={[[]]}}}
    ]
  ]
\end{forest}
\end{document}