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Linked Lists

Linked Lists. list elements are stored, in memory, in an arbitrary order explicit information ( called a link) is used to go from one element to the next. a. b. c. d. e. c. a. e. d. b. Memory Layout. Layout of L = (a,b,c,d,e) using an array representation.

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Linked Lists

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  1. Linked Lists list elements are stored, in memory, in an arbitrary order explicit information (called a link) is used to go from one element to the next

  2. a b c d e c a e d b Memory Layout Layout of L = (a,b,c,d,e) using an array representation. A linked representation uses an arbitrary layout.

  3. first Linked Representation c a e d b pointer (or link) in e is NULL use a variable first to get to the first element a

  4. first NULL a b c d e Normal Way To Draw A Linked List link or pointer field of node data field of node

  5. Chain first NULL a b c d e A chain is a linked list in which each node represents one element. There is a link or pointer from one element to the next. The last node has a NULL (or 0) pointer.

  6. link data Node Representation typedef struct listNode *listPointer; typedef struct { char data; listPointer link; } listNode;

  7. first NULL a b c d e get(0) desiredNode = first; // gets you to first node return desiredNode->data;

  8. first NULL a b c d e get(1) desiredNode = first->link; // gets you to second node return desiredNode->data;

  9. first NULL a b c d e get(2) desiredNode = first->link->link; // gets you to third node return desiredNode->data;

  10. first NULL a b c d e get(5) desiredNode = first->link->link->link->link->link; // desiredNode = NULL return desiredNode->data; // NULL.element

  11. first NULL a b c d e Delete An Element delete(0) deleteNode = first; first = first->link; free(deleteNode);

  12. first b beforeNode NULL a b d e c c c delete(2) first get to node just before node to be removed beforeNode = first->link;

  13. delete(2) first null a b c d e save pointer to node that will be deleted beforeNode deleteNode = beforeNode->link;

  14. delete(2) first null a b c d e now change pointer in beforeNode beforeNode beforeNode->link = beforeNode->link->link; free(deleteNode);

  15. first NULL f a b c d e newNode insert(0,’f’) Step 1: get a node, set its data and link fields MALLOC( newNode, sizeof(*newNode)); newNode->data = ‘f’; newNode->link = NULL;

  16. first NULL f a b c d e newNode insert(0,’f’) Step 2: update first first = newNode;

  17. newNode f first NULL a b c d e c beforeNode insert(3,’f’) first find node whose index is 2 • next create a new node and set its data and link fields • finally link beforeNode to newNode

  18. newNode f first NULL a b c d e beforeNode c insert(3,’f’) beforeNode = first->link->link; MALLOC( newNode, sizeof(*newNode)); newNode->data = ‘f’; newNode->link = beforeNode->link; beforeNode->link = newNode;

  19. headerNode NULL a b c d e Chain With Header Node

  20. Empty Chain With Header Node headerNode NULL

  21. firstNode a b c d e Circular List

  22. firstNode lastNode NULL NULL a b c d e Doubly Linked List

  23. firstNode a b c d e Doubly Linked Circular List

  24. headerNode a b c d e Doubly Linked Circular List With Header Node

  25. Empty Doubly Linked Circular List With Header Node headerNode

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