Linked List’s Examples

1. Linked List’s Examples Salim Malakouti

2. Linked List? Value Pointer Pointer 5 2 3 Node

3. Node Class • public class Node<T> { • /** • * Data • */ • private T value; • /** • * Pointer to the next Node • */ • private Node<T> next; • public Node(T value, Node<T> next) { • this.setValue(value); • this.setNext(next); • } • … • … • }

4. ComprehensionQuestions

5. Question 1 • If we just want to iterate over the list and print all values, which one is faster why? • Array • Linked List?

6. Answer • Array • Because all elements are beside each other. There is no need for scanning the file.

8. Algorithmic Questions

9. Question 1 How to add a new value to the list?

10. Question 1 • /** • * This function simply adds a new node to the list by adding it to the • * beginning. • * • * @param value • */ • public void add(T value) { • Node<T> tmp = getHead(); • setHead(new Node<>(value)); • getHead().setNext(tmp); • }

11. Question 2 How to clear the Linked List?

12. Clear • /** • * This function simply clears the list • */ • public void clear() { • setHead(null); • }

13. Question 3 How to find the size?

14. Size • /** • * Computes the size of the list. • * • * @return • */ • public int size() { • Node<T> current = getHead(); • int size = 0; • while (current != null) { • current = current.getNext(); • size++; • } • returnsize; • }

15. Size Recursive • /** • * Computes the size of the list but using a recursive function. • * • * @return • */ • public intsizeRecursive() { • return sizeR(head); • } • /** • * The inner part of the recursive size • * @param head • * @return • */ • private intsizeR(Node<T> head) { • if (head == null) • return 0; • else • return sizeR(head.getNext()) + 1; • }

16. Question 4 How to get the last value?

17. Get Tail • /** • * This function returns the last element. • * • * @return • */ • public Node<T> getTail() { • Node<T> current = getHead(); • while (current.getNext() != null) { • current = current.getNext(); • } • return current; • }

18. Get Tail Recursive • public Node<T> getTailRecursive() { • return tailR(head); • } • /** • * Inner function for finding tail recursively • * @param node • * @return • */ • private Node<T> tailR(Node<T> node) { • if (node.getNext() == null) • return node; • return tailR(node.getNext()); • }

19. Question 5 How to append to lists?

20. Append • /** • * Append the input list to the end of this list. • * • * @param l • */ • publicvoidappend(LinkedList<T> l) { • Node<T> tail = getTail(); • if (tail == null) { • head = l.getHead(); • } else { • tail.setNext(l.getHead()); • }

21. Question 6 How to check if a specific value is in the list?

22. Has Value • /** • * This function checks to see if there is a node with value equal to the • * input. • * • * @param value • */ • public booleanhasValue(T value) { • Node<T> current = getHead(); • while (current != null) { • if (current.getValue().equals(value)) { • return true; • } • current = current.getNext(); • } • return false; • }

23. Question 7 How to find the ith element?

24. Get ith • /** • * This function returns the ith item in the list. • */ • public T get(int index) { • Node<T> current = getHead(); • int i = 0; • while (current != null) { • if (i == index) • returncurrent.getValue(); • current = current.getNext(); • i++; • } • returnnull; • }

25. Question 8 How to remove a specific element?

26. Remove • /** • * This functions removes nodes in the list equal to the input. Only one at • * a time. • * • * @param value • */ • public void remove(T value) { • Node<T> pre = null; • Node<T> current = getHead(); • while (current != null) { • if (current.getValue().equals(value)) { • if (pre != null) { • pre.setNext(current.getNext()); • } else { • setHead(current.getNext()); • } • break; • } • pre = current; • current = current.getNext(); • } • }

27. Question 9 How to reverse the list?

28. Reverse • /** • * This function simply reverses the list • */ • public void reverse() { • Node<T> next = getHead(); • Node<T> pre = null; • Node<T> tmp = null; • while (next != null) { • tmp = next; • next = next.getNext(); • tmp.setNext(pre); • pre = tmp; • } • setHead(tmp); • }

29. Question 10 How to insert in ith position?

30. Insert in ith position • public void insert(int index, T value) { • Node<T> current = getHead(); • Node<T> pre = null; • int i = 0; • while (current != null) { • if (i == index) { • if (pre != null) { • pre.setNext(new Node(value, current)); • } else { • setHead(new Node(value, current)); • } • } • pre = current; • current = current.getNext(); • i++; • } • }