如何在LaTex中正确显示我的AVL树？一个独奏的左孩子直接垂下来

Question

下面的代码几乎完美无缺,但是9,7的孩子直接挂了而不是作为左孩子.我怎么能纠正这个？

\usepackage{tikz}
\usepackage{xytree}
\begin{tikzpicture}[level/.style={sibling distance=60mm/#1}]
    \node [circle,draw] {4}
      child {
        node [circle,draw] {2}
            child {node [circle,draw] {1}
       }
        child {
            node [circle,draw]{3}
        }
      }
      child {node [circle,draw] {6}
        child {node [circle,draw]  {5}
        }
      child {node [circle,draw]  {9}
        child {node [circle, draw]  {7}}
      }
    };

\end{tikzpicture}}

谢谢,CB

Answer 1

下面的代码适合我.它基于您的代码和更改

1)使用tikz库树和2)更改单个节点的格式(节点7)

有关更多信息,请参阅tikz手册

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{trees}

\begin{document}

\begin{tikzpicture}[level/.style={sibling distance=60mm/#1}]
    \node [circle,draw] {4}
      child {
        node [circle,draw] {2}
            child {node [circle,draw] {1}
       }
        child {
            node [circle,draw]{3}
        }
      }
      child {node [circle,draw] {6}
        child {node [circle,draw]  {5}
        }
      child {node [circle,draw]  {9}
        child[grow via three points={one child at (-1,-1) and two children at (-.5,1) and (.5,1)}] {node [circle, draw]  {7}}
      }
    };

\end{tikzpicture}

\end{document}

Answer 2

按照建议查阅 tikz 手册后，我能够按如下方式更正此问题。

\begin{tikzpicture}[level/.style={sibling distance=60mm/#1}]
    \node [circle,draw] {4}
      child {
        node [circle,draw] {2}
            child {node [circle,draw] {1}
       }
        child {
            node [circle,draw]{3}
        }
      }
      child {node [circle,draw] {6}
        child {node [circle,draw]  {5}
        }
      child {node [circle,draw]  {9}
        child {node [circle, draw]  {7}} 
        child [missing]
        }
    };

    \end{tikzpicture}