restructure and add ipi texs

ws2019/ipi/uebungen/cpp_headers/Set.hh

@@ -0,0 +1,15 @@
+template<class T>
+class Set : private DLList<T> {
+public :
+  // Default-Konstruktoren + Zuweisung OK
+
+  typedef typename DLList<T>::Iterator Iterator;
+  Iterator begin();
+  Iterator end();
+    
+  bool empty ();
+  bool member (T t);
+  void insert (T t);
+  void remove (T t);
+  // union, intersection, ... ?
+} ;