Added AST warm-up

Misc/Warm-Ups/ast.tex

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+\documentclass[
+	solutions,
+	nowarning,
+	singlenumbering,
+	nopagenumber
+]{../../resources/ormc_handout}
+
+\usepackage[linguistics]{forest}
+
+\begin{document}
+
+	\maketitle
+		{Warm-Up: What's an AST?}
+		{Prepared by Mark on \today. \\ Based on a true story.}
+
+
+	Say you have a valid string of simple arithmetic that contains no unary operators (like $3!$ or $-4$) and no parenthesis:
+	$$
+	3 + 9 \times 8 \div 5 \land 6
+	$$
+
+	You may assume that all numbers and operators in this string consist of exactly one character. \\
+
+	Devise an algorithm that turns this string into a tree (as shown below), respecting the order of operations $[\land, \times, \div, +, -]$.
+
+	\begin{center}
+	\begin{forest}
+		[$+$
+			[3]
+			[$\div$
+				[$\times$[9][8]]
+				[$\land$[5][6]]
+			]
+		]
+	\end{forest}
+	\end{center}
+
+\end{document}