连接同一层上的 2 个节点

Question

我不太清楚如何将两个非子节点连接在一起。如能提供任何帮助，我将不胜感激。

\usepackage{tikz}
\usetikzlibrary{trees}

\begin{graph}{2.5in}
    \centering
    \begin{tikzpicture}[
        level distance = 2.5cm,
        level 1/.style = {sibling distance=4.0cm},
        level 2/.style = {sibling distance=5.5cm},
        level 3/.style = {sibling distance=5.0cm},
     every node/.style = {circle,draw},
            lbl/.style = {rectangle, draw=none, #1,% position
                          font=\footnotesize}
                             ]
     \node (Root) {Start}
         child {node {Node 1}
             child {node {Node 4}
                 child {node {Goal 1}
                 edge from parent node[lbl=left] {$3$}
                 }
             edge from parent node[lbl=left] {$3$}
            }
         edge from parent node[lbl=left] {$3$}
           }
         child { node {Node 2}
            child{ node {Goal 2} 
            edge from parent node[lbl=left] {$12$}}
            edge from parent node[lbl=left] {$12$}
         }
         child { node {Node 3}
             child { node {Node 6} 
                child {node {Node 8}
                child {node {Goal 3}
                edge from parent node[lbl=right] {$1$}}
                edge from parent node[lbl=right] {$1$}}
                edge from parent node[lbl=right] {$1$}}
                edge from parent node[lbl=right] {$1$}
               };
         \end{tikzpicture}

\end{graph}

我想将目标 2 连接到节点 4。

Answer 1

节点会自动命名。这使得连接它们变得简单直接。

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{trees}
\begin{document}
    \begin{tikzpicture}[
    level distance = 2.5cm,
    level 1/.style = {sibling distance=4.0cm},
    level 2/.style = {sibling distance=5.5cm},
    level 3/.style = {sibling distance=5.0cm},
 every node/.style = {circle,draw},
        lbl/.style = {rectangle, draw=none, #1,% position
                      font=\footnotesize}
                         ]
 %
 \node (Root) {Start}
     child {node {Node 1}
         child {node {Node 4}
             child {node {Goal 1}
             edge from parent node[lbl=left] {$3$}
             }
         edge from parent node[lbl=left] {$3$}
        }
     edge from parent node[lbl=left] {$3$}
       }
     child { node {Node 2}
        child{ node {Goal 2} 
        edge from parent node[lbl=left] {$12$}}
        edge from parent node[lbl=left] {$12$}
     }
     child { node {Node 3}
         child { node {Node 6} 
            child {node {Node 8}
            child {node {Goal 3}
            edge from parent node[lbl=right] {$1$}}
            edge from parent node[lbl=right] {$1$}}
            edge from parent node[lbl=right] {$1$}}
            edge from parent node[lbl=right] {$1$}
           };
\draw (Root-1-1) -- (Root-2-1) node[midway,above,lbl]{$7$};
\end{tikzpicture}
\end{document}