chore: Add course material

397/Ex41/Subject.h

@@ -0,0 +1,18 @@
+
+#ifndef SUBJECT_H
+#define SUBJECT_H
+
+class Observer;
+
+#include <set>
+
+class Subject {
+  public:
+    // TODO: Declare the attach() function that adds an Observer to the set
+  protected:
+    // TODO: Declare the notify() function that calls all the update functions
+  private:
+    // TODO: Define a set of Observer pointers
+};
+
+#endif