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Comparison summary

Array based (dynamic) Keeps place for up to 4N elements Each element takes 1 memory places Fast accession time Slow removals and insertion (due to need of copying data and resizing array). Reference based (LL) Keeps place for exactly N elements Each element takes 2 memory places

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Comparison summary

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  1. Array based (dynamic) Keeps place for up to 4N elements Each element takes 1 memory places Fast accession time Slow removals and insertion (due to need of copying data and resizing array) Reference based (LL) Keeps place for exactly N elements Each element takes 2 memory places Slow accession time Slow removals and insertion (due to accession) Comparison summary

  2. Passing a Linked List to a Method • A method with access to a linked list’s head reference has access to the entire list • When head is an actual argument to a method, its value is copied into the corresponding formal parameter Figure 5-19 A head reference as an argument

  3. Examples • Merge() method, takes 2 sorted lists and returns one sorted list containing all elements (the original lists can be destroyed) • Fast insertions and deletions at the beginning of the list using array-based implementation • Fast insertion at the end and fast deletion at the beginning using linked-list (alternatively, array-based) implementation [tail reference]

  4. Variations of the Linked List:Tail References • tail references • Remembers where the end of the linked list is • To add a node to the end of a linked list tail.setNext(new Node(request, null)); Figure 5-22 A linked list with head and tail references

  5. Doubly Linked List • Each node references both its predecessor and its successor • Dummy head nodes are useful in doubly linked lists Figure 5-26 A doubly linked list

  6. Doubly Linked List • To delete the node that curr references curr.getPrecede().setNext(curr.getNext()); curr.getNext().setPrecede(curr.getPrecede()); Figure 5-28 Reference changes for deletion

  7. Doubly Linked List • To insert a new node that newNode references before the node referenced by curr newNode.setNext(curr); newNode.setPrecede(curr.getPrecede()); curr.setPrecede(newNode); newNode.getPrecede().setNext(newNode); Figure 5-29 Reference changes for insertion

  8. Eliminating special cases in Doubly Linked List Figure 5-27 a) A circular doubly linked list with a dummy head node; b) an empty list with a dummy head node

  9. Doubly Linked List • Circular doubly linked list • precede reference of the dummy head node references the last node • next reference of the last node references the dummy head node • Eliminates special cases for insertions and deletions

  10. Doubly Linked List - benefits • Fast insertions and deletions at both ends of the list • To perform deletion and insertion, we need reference to the current node (to node after place where we are inserting). (Usual implementation of LinkedLists)

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