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Linked List - I

Linked List - I. Abstract Data Type (ADT). ADT is a data type whose properties (domain and operations) are specified independently of any particular implementation. Logical (or ADT) level: abstract view of the domain and operations.

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Linked List - I

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  1. Linked List - I

  2. Abstract Data Type (ADT) • ADT is a data type whose properties (domain and operations) are specified independently of any particular implementation. • Logical (or ADT) level:abstract view of the domain and operations. • Implementation level:specific representation of the structure to hold the data items, and the coding for operations.

  3. 4 Basic Kinds of ADT Operations • Constructor/Destructor – creates/deletes a new instance (object) of an ADT. • Transformer -- changes the state of one or more of the data values of an instance. • Observer -- allows us to observe the state of one or more of the data values of an instance without changing them. • Iterator -- allows us to process all the components in a data structure sequentially.

  4. List • Linear relationship Each element except the first has a unique predecessor, and each element except the last has a unique successor. • Length The number of items in a list; the length can vary over time.

  5. Class ShoppingList class ShoppingList { public : int LengthIs ( ) const ; void RetrieveItem (int pos) ; void InsertItem (const Item& item, int pos ) ; void RemoveItem (int pos); void DeleteAll ( ); private : int size ; Node *front ; } ;

  6. Pointer to front node Data carried in node Pointer to next node A B C NULL Nodes Singly Linked List Diagram

  7. Item item; Node *link; A Class Node class Node { public: Node(Item i){item = i}; private: Item item; Node *link; }; Insert an item/node into shopping list? Delete an item/node?

  8. anItem pos D 0 size 3 Front Insert Example (1 of 6) void ShoppingList::insert(const Item & anItem, int pos) { Node *prev, //ignore prev ptr for the FrontInsert example *cur; Inserting D at position 0 prev cur ? ? front item link item link item link A B C

  9. anItem pos D 0 Front Insert Example (2 of 6) assert(pos >= 0 && pos <= size); size++; cur ? size front 4 item link item link item link A B C

  10. anItem pos D 0 Front Insert Example (3 of 6) if (pos == 0) { // Inserting at the front cur = front; cur size front 4 item link item link item link A B C

  11. anItem pos D 0 Front Insert Example (4 of 6) front = new Node(anItem); cur size front 4 item link item link item link A B C item link D ?

  12. anItem pos D 0 Front Insert Example (5 of 6) front->link = cur; cur size front 4 item link item link item link A B C item link D

  13. Front Insert Example (6 of 6) return; } size front 4 item link item link item link A B C item link D

  14. anItem pos A 0 front Empty Insert Example (1 of 6) void ShoppingList::insert(const Item & anItem, int pos) { Node *prev, //ignore prev for EmptyInsert example *cur; Inserting A at position 0 in empty list cur ? size 0

  15. anItem pos A 0 front Empty Insert Example (2 of 6) assert(pos >= 0 && pos <= size); size++; cur ? size 1

  16. anItem pos A 0 front Empty Insert Example (3 of 6) if (pos == 0) { // Inserting at the front cur = front; cur size 1

  17. anItem pos A 0 item link A front Empty Insert Example (4 of 6) front = new Node(anItem); cur size 1 ?

  18. anItem pos A 0 item link A front Empty Insert Example (5 of 6) front->link = cur; cur size 1

  19. item link A front Empty Insert Example (6 of 6) return; } size 1

  20. anItem pos D 2 size 3 Middle Insert Example (1 of 8) void ShoppingList::insert(const Item & anItem, int pos) { Node *prev, *cur; Inserting D at position 2 prev cur ? ? front item link item link item link A B C

  21. anItem pos D 2 size 4 Middle Insert Example (2 of 8) assert(pos >= 0 && pos <= size); size++; prev cur ? ? front item link item link item link A B C

  22. anItem pos D 2 size 4 Middle Insert Example (3 of 8) prev = NULL; cur = front; prev cur front item link item link item link A B C

  23. anItem pos D 1 size 4 Middle Insert Example (4 of 8) while (pos > 0) { prev = cur; cur = cur->link; pos--; } First Iteration prev cur front item link item link item link A B C

  24. anItem pos D 0 size 4 Middle Insert Example (5 of 8) while (pos > 0) { prev = cur; cur = cur->link; pos--; } Second Iteration prev cur front item link item link item link A B C

  25. anItem pos D 0 size 4 Middle Insert Example (6 of 8) prev->link = new Node(anItem); prev cur front item link item link item link A B C item link D ?

  26. anItem pos D 0 size 4 Middle Insert Example (7 of 8) prev->link->link = cur; prev cur front item link item link item link A B C item link D

  27. size 4 Middle Insert Example (8 of 8) } front item link item link item link A B C item link D

  28. anItem pos D 3 size 3 End Insert Example (1 of 8) void ShoppingList::insert(const Item & anItem, int pos) { Node *prev, *cur; Inserting D at position 3 prev cur ? ? front item link item link item link A B C

  29. anItem pos D 3 size 4 End Insert Example (2 of 8) assert(pos >= 0 && pos <= size); size++; prev cur ? ? front item link item link item link A B C

  30. anItem pos D 3 size 4 End Insert Example (3 of 8) prev = 0; cur = front; prev cur 0 front item link item link item link A B C

  31. anItem pos D 2 size 4 End Insert Example (4 of 8) while (pos > 0) { prev = cur; cur = cur->link; pos--; } First Iteration prev cur front item link item link item link A B C

  32. anItem pos D 1 size 4 End Insert Example (5 of 8) while (pos > 0) { prev = cur; cur = cur->link; pos--; } Second Iteration prev cur front item link item link item link A B C

  33. anItem pos D 0 size 4 End Insert Example (6 of 8) while (pos > 0) { prev = cur; cur = cur->link; pos--; } Third Iteration prev cur front item link item link item link A B C

  34. anItem pos D 0 size 4 End Insert Example (7 of 8) prev->link = new Node(anItem); prev->link->link = cur; prev cur front item link item link item link A B C item link D

  35. size 4 End Insert Example (8 of 8) } front item link item link item link A B C item link D

  36. void ShoppingList::insert(const Item & anItem, int pos) { Node *prev, *cur; assert(pos >= 0 && pos <= size); size++; if (pos == 0) { // Inserting at the front cur = front; front = new Node(anItem); front->link = cur; return; } prev = NULL; cur = front; while (pos > 0) { prev = cur; cur = cur->link; pos--; } prev->link = new Node(anItem); prev->link->link = cur; }

  37. pos 1 size 3 Remove Example (1 of 7) void ShoppingList::remove(int pos) { Node *cur, *prev; Removing at position 1 prev cur ? ? front item link item link item link A B C

  38. pos 1 size 2 Remove Example (2 of 7) assert(pos >= 0 && pos < size); size--; prev cur ? ? front item link item link item link A B C

  39. pos 1 size 2 Remove Example (3 of 7) prev = NULL; cur = front; prev cur front item link item link item link A B C

  40. Delete the node pointed by cur pos 0 size 2 Remove Example (4 of 7) while (pos > 0) { prev = cur; cur = cur->link; pos--; } First iteration prev cur front item link item link item link A B C

  41. pos 0 size 2 Remove Example (5 of 7) prev->link = cur->link; prev cur front item link item link item link A B C

  42. pos 0 size 2 Remove Example (6 of 7) delete cur; prev cur front item link item link item link A B C

  43. size 2 Remove Example (7 of 7) } front item link item link A C

  44. kil ? size 3 Delete All Example (1 of 8) void ShoppingList::deleteAll() { Node *kil; item link item link item link A B C front

  45. kil size 3 Delete All Example (2 of 8) while (front != NULL) { kil = front; front = front->link; First iteration item link item link item link A B C front

  46. kil size 3 Delete All Example (3 of 8) kil->link = NULL; delete kil; } First iteration item link item link item link A B C front

  47. kil size 3 Delete All Example (4 of 8) while (front != NULL) { kil = front; front = front->link; Second iteration item link item link B C front

  48. kil size 3 Delete All Example (5 of 8) kil->link = NULL; delete kil; } Second iteration item link item link B C front

  49. kil size 3 Delete All Example (6 of 8) while (front != NULL) { kil = front; front = front->link; Third iteration item link C front

  50. kil size 3 Delete All Example (7 of 8) kil->link = 0; delete kil; } Third iteration item link C front 0

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