Klausur WS 23

Aufgabe 4

a)

public boolean contains(int x) {
	for (Node p = head; p != null; p = p.next) {
		if (p.data == x)
			return true;
	}
	return false;
}

b)

public void add(int x) {
	end.next = new Node(null, x);
	end = end.next;
}

c)

public List(List l) {
	begin = end = null;
	
	for (Node p = l.begin; p != null; p = p.next)
		this.add(p.data);
}

d)

public boolean startsWith(List l) {
	if (begin == null || l.begin == null)
		return begin == l.begin;
		
	Node p = begin;
	Node q = l.begin;
	while (p != null && q != null) {
		if (p.data != q.data)
			return false;
		p = p.next;
		q = q.next;
	}
	
	return q == null;
}

e)

public List add(int x) {
	end.next = new Node(null, x);
	end = end.next;
	return this;
}

---

Aufgabe 5

a)

		11
	2			15
1		8	12

b)

private int heightR(Node p) {
	if (p == null)
		return -1; 
	return Math.max(heightR(p.left), heightR(p.right)) + 1;
}

c)

public List<Integer> collect(Predicate<Integer> pred) {
	List<Integer> l = new ArrayList<>();
	collectR(root, pred, l);
	return l;
}
 
private void collectR(Node p, Predicate<Integer> pred, List<Integer> l) {
	if (p != null) {
		collectR(p.left, pred, l);
		if (pred.test(p.data))
			l.add(p.data);
		collectR(p.right, pred, l);
	}
}

d)

List<Integer> list = t.collect(x -> x % 2 == 0);

---

Aufgabe 6

a)

public void addLike(String res, String pers) {
	if (isLikedBy.get(res) == null)
		isLikedBy.put(res, Set.of(pers));
	else
		isLikedBy.get(res).add(pers);
}

b)

public Set<String> getLikes(String res) {
	return isLikedBy.get(res);
}

c)

1. Möglichkeit

public Set<String> getRestaurants(String pers) {
	Set<String> s = new HashSet<>();
	for (Map.Entry<String, Set<String> entry : isLikedBy.entrySet()) {
		if (entry.getValue().contains(pers))
			s.add(entry.getKey());
	}
	return s;
}

2. Möglichkeit

public Set<String> getRestaurants(String pers) {
	return isLikedBy.entrySet().stream()
		.filter(entry -> entry.getValue().contains(pers))
		.map(entry -> entry.getKey())
		.toSet();
}

d)

public Set<String> top10() {
	return isLikedBy.entrySet().stream()
			.sorted((res1, res2) 
				-> res1.getValue().size() - res2.getValue().size())
			.limit(10)
			.map(entry -> entry.getKey())
			.collect(Collectors.toSet());
}

---

Aufgabe 7

a)

BiFunction<Messwert, Double, Messwert>

b)

Messwert[typ="Temp", plz="78464", wert=30.0]

c)

mLst.replaceAll(x -> incr.apply(x, 1.1));

d)

boolean tempIntervall = mLst.stream()
		.filter(m -> m.type.equals("Temp"))
		.allMatch(m -> m.wert >= a && m.wert <= b);
		
System.out.println(tempIntervall);

e)

Optional<Messwert> w = mLst.stream()
		.filter(x -> x.typ.equals("CO2"))
		.max((x1, x2) -> (int) (x1.wert - x2.wert));
System.out.println(w.get().plz);

f)

plz:78364:78464:78362:78462:78464:78567

g)

{CO2=[78364, 78362, 78462, 78464], Temp=[78464, 78567]}

Aufgabe 8)

a)
Es prüft ob das Element e in der Liste t gibt.

b)
O(n)

c)
.contains(e)

d)
T(log n)