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notes-and-examples/2026.08.27/topological_sort.md

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+## Class ordering
+
+These are some classes for Chapman University, for
+the [computer science program](https://catalog.chapman.edu/preview_program.php?catoid=33&poid=6408&print).
+
+![An ordering of classes for Chapman University.](classes.png)
+
+> [!QUESTION] What type of graph is this?
+
+We say that a class is a *prerequisite* or a *dependency* of another class
+if we need to take it before that other class. So, we need to take CPSC 230
+before CPSC 231, for example.
+
+Could you come up with something like this for your school?
+
+## The algorithm
+
+If you were to come up with a list of classes, such that the list of classes
+is in the order which you need to take them, what would that look like?
+
+This order is what we're trying to achieve with the topological sort
+algorithm. Note that there can be multiple correct solutions.
+
+## The exercise
+
+Let's write the algorithm. First, test it against the Chapman classes, then
+put in your classes and see how it fares against that.