## 1.画分类的图
```LaTeX
\documentclass{article}
\usepackage{forest}
\begin{document}
\begin{forest}
for tree = {math content,grow'=east}
[1 [P(A_1)
[P(B|A_1)]
[P(\bar B|A_1)]]
[P(A_2)
[P(B|A_2)]
[P(\bar B|A_2)]]]]
\end{forest}
\end{document}
```
## 1.画分类的图
```LaTeX
\documentclass{article}
\usepackage{forest}
\begin{document}
\begin{forest}
for tree = {math content,grow'=east}
[1 [P(A_1)
[P(B|A_1)]
[P(\bar B|A_1)]]
[P(A_2)
[P(B|A_2)]
[P(\bar B|A_2)]]]]
\end{forest}
\end{document}
```