Question 5
==========

a) Übersetzungsfehler. Es kann keine Instanz einer Klasse mit
   pure virtual functions erzeugt werden.

b) okay.

c) okay.

d) okay.

e) okay.

f) okay.

g) Übersetzungsfehler. Klasse E ist keine Unterklasse von I.

h) okay.

i) Übersetzungsfehler. Klasse C ist keine Unterklasse von D (umgekehrt).

j) okay. (Der Variablen h wird der Null-Zeiger zugewiesen).

k) okay. (Der Variablen h wird der Zeiger auf D-Objekt d zugewiesen).

l) okay.

m) okay.

n) okay.

o) Übersetzungsfehler. Klasse E ist keine Unterklasse von I.

Question 4
==========

map< string, set<int> > occurrences(list<string> text)
{
  map< string, set<int> > map;
  int pos = 0;
  for (string word : text)
  {
    set<int> set;
    auto it = map.find(word);
    if (it != map.end()) set = *it;
    set.insert(pos);
    map[word] = set;
    pos++;
  }
  return map;
}

Question 3
==========

template<class T> class ArrayQueue: public BoundedQueue<T>
{
  T* array;
  int length;
  int number;
  int head;
  int tail;

  void copy(const ArrayQueue& q)
  {
    length = q.length;
    number = q.number;
    head = q.head;
    tail = q.tail;
    array = new T[length];
    for (int i = 0; i < length; i++) array[i] = q.array[i];
  }

public:

  ArrayQueue(int len)
  {
    array = new T[len];
    length = len;
    number = 0;
    head = 0;
    tail = 0;
  }

  ~ArrayQueue() { delete[] array; }
  ArrayQueue(const ArrayQueue& q) { copy(q); }
  ArrayQueue& operator(const ArrayQueue &q)
  { delete[] array; copy(q); }

  bool isempty() { return number == 0; }
  bool isfull() { return number == length; }

  void put(T& elem)
  {
    array[tail] = elem;
    tail = (tail+1)%length; // tail++; if (tail == length) tail = 0;
    number++;
  }

  T get()
  {
    T elem = array[head];
    head = (head+1)%length;
    number--;
    return elem;
  }
};

Question 2
==========

int printSongs(Archive* archive, int year, string interpreter)
{
  int len = 0;
  int n = archive->size();
  for (int i = 0; i < n; i++)
  {
    Album* album = archive->album(i);
    int year0 = album->year();
    if (year0 != year) continue;
    int len0 = printAlbum(album, interpreter);
    len += len0;
  }
  return len;
}

int printAlbum(Album* album, string interpreter)
{
  int len = 0;
  string title = album->title();
  int n = album->size();
  for (int i = 0; i < n; i++)
  {
    Song* song = album->song(i);
    string interpreter0 = song->interpreter();
    if (interpreter0 != interpreter) continue;
    cout << title << ": " << song->title() << endl;
    len += song->length();
  }
  return len;
}

Question 1
==========

class Work
{
  int cents;
  int min;

public:

  Work(int c, int m = 0): cents(c), min(m) { }
  /* Work(Work &w): cents(w.cents), min(w.min) { } */

  void add(int m) { min += m; }

  void printSalary() const
  {
    int total = cents*min;
    cout << (total/100) << ",";
    int c = total%100;
    if (c < 10) << "0";
    cout << c;
  }

  bool subtract(int m)
  {
    if (min < m) return false;
    min -= m;
    return true;
  }

  static void reset (Work& w) { w.min = 0; }
  void reset() { /* this-> */ min = 0; }

  int compare(Work w)
  {
    int t1 = cents*min;
    int t2 = w.cents*w.min;
    if (t1 == t2) return 0;
    if (t1 < t2) return -1;
    return 1;
  }
};