BranchAndBoundTree_tikz.tex

\documentclass[tikz,border=5pt]{standalone}
\usepackage{forest}
\begin{document}
  \tikzset{
    every label/.append style={font=\scriptsize},
    my edge labels/.style={font=\scriptsize},
    dominant/.append style={label=below:$dominant$},
  }
  \begin{forest}
    for tree={
      circle,
      draw,
      minimum width=2.5em,
      l sep+=1.5em,
      s sep+=1em,
      anchor=center,
      edge path={
        \noexpand\path[\forestoption{edge}](!u.parent anchor)--(.child anchor)[my edge labels]\forestoption{edge label};
      },
    },
    delay={
      where n=1{
        edge label/.wrap 2 pgfmath args={
          node[midway, left]{$b_{#1}={#2}$}}{level}{n}
      }{
        edge label/.wrap 2 pgfmath args={
          node[midway, right]{$b_{#1}={#2}$}}{level}{n}
      },
    }
    [0, label={left:$L_2=L_3=3$}
      [1
        [2
          [3
            [4
            ]
            [12, label={below:$L_2=4$}
            ]
          ]
          [,phantom]
        ]
        [13, s sep+=1.5em, label={right:$L_3=3$}
          [{\phantom{a}}, dominant
          ]
          [14, label={below:$L_3=4$}
          ]
          [15, label={right:$L_3=3$}
            [, dominant
            ]
            [16, label={right:$L_3=3$}
            ]
          ]
        ]
      ]
    ]
  \end{forest}
\end{document}