家谱“出错”

Question

尝试制作一棵简单的树，但当我完成时，我意识到我完全走错了路……如果能得到一些帮助，尝试以“正确”的方式制作它，我将不胜感激。哦，还要圈出最后的 5/3

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[swedish]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{tikz}
\usetikzlibrary{matrix}
\usetikzlibrary{calc,trees,positioning,arrows,fit,shapes,decorations.markings}

\begin{document}
\begin{tikzpicture}
\matrix(m)[matrix of math nodes,column sep=0.5cm,row sep=0.3cm,]{
     & & & \dfrac{1}{1} & & & \\
     & \dfrac{1}{2} & & & & \dfrac{2}{1} & \\
     \dfrac{1}{3} & & \dfrac{3}{2} & & \dfrac{2}{3} & & \dfrac{3}{1} \\
     \vdots & & \vdots & & & \dfrac{5}{3} & \vdots \\
     };
\draw[->]
(m-1-4)edge(m-2-2)
(m-1-4)edge(m-2-6)
(m-2-2)edge(m-3-1)
(m-2-2)edge(m-3-3)
(m-2-6)edge(m-3-5)
(m-2-6)edge(m-3-7)
(m-3-5)edge(m-4-6);
\end{tikzpicture}
\end{document}

Answer 1

可以forest轻松改变树的生长方式。它有一个reversed选项。

\documentclass{standalone}
\usepackage{forest}
\usepackage{amsmath}
\usepackage{etex}

\begin{document}
\begin{forest}
for tree={edge = ->, reversed}
[$\dfrac{1}{1}$
    [$\dfrac{1}{2}$
        [$\dfrac{1}{3}$[\vdots]]
        [$\dfrac{3}{2}$[\vdots]]]
    [$\dfrac{2}{1}$
        [$\dfrac{2}{3}$[,phantom][$\dfrac{5}{3}$, draw, circle]]
        [$\dfrac{3}{1}$[\vdots]]]]
\end{forest}
\end{document}