11 15 (doubly linked list)
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1) Doubly linked lists contain nodes with pointers to both the previous and next nodes, allowing traversal in either direction. 2) Common operations on doubly linked lists include insertion and deletion at the beginning, end, or within the list by node value. 3) Insertion and deletion have some special cases to handle when the target node is the first, last, or only node in the list.
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11 15 (doubly linked list)
- 1. DOUBLY LINKED LIST CREATED BY: 1507011- TAHMINA RAHMAN 1507012- SAMIUL AZIM 1507013- FABLIHA HAQUE 1507014- SALIM SHADMAN ANKUR 1507015- SAIFUR RAHMAN
- 2. TOPICS: โข linked lists โข doubly linked list โข Creation and traversing of doubly linked list โข Insertion and deletion on doubly linked list โข complexity of insertion and deletion โข Advantages and disadvantages of doubly linked list
- 3. LINKED LIST ๏ Like arrays, Linked List is a linear data structure ๏ Unlike arrays, linked list elements are not stored at contiguous location ๏ the elements are linked using pointers ๏ does not have any index
- 4. ADDRESSES FOR LINKED LIST AND ARRAY Linked List Arrray
- 5. WHY WE USE LINKED LIST Arrays can be used to store linear data of similar types, but arrays have following limitations.. 1) The size of the arrays is fixed . 2) Inserting a new element in an array of elements is expensive, because room has to be created for the new elements and to create room existing elements have to shifted.
- 6. DOUBLY LINKED LIST โข A Doubly Linked List (DLL) contains an extra pointer, typically called previous pointer, together with next pointer and data which are there in singly linked list. โข Every nodes in the doubly linked list has three fields: 1. Left Pointer (prev) 2. Right Pointer (next) 3. Data (info)
- 7. DOUBLY LINKED LIST โข Prev - address of the previous node โข Next - address of the next node โข Info - information of the node โข head - address of the first node Prev Info Next node
- 8. CREATION OF DOUBLY LINKED LIST Steps- 1: Head := NULL (as global) 2: New Node (Ptr) // set data and prev , next to NULL 3: If Head = NULL ๏ Head := ptr ๏ temp := ptr 4. If not ๏ temp โ next := ptr ๏ Ptr โ prev := temp ๏ temp := ptr
- 9. CREATION OF DOUBLY LINKED LIST NULL data1 NULL 0x80 0x80 data2 NULLNULL data1 0x81 0x810x80 0x80 data2 0x81NULL data1 0x81 0x81 data3 NULL 0x80 0x81 0x82 No element inserted Third element inserted: Second element inserted: First element inserted: Empty list Head temp Head temp Head temp
- 10. TRAVERSING 0x80 9 0x82NULL 8 0x81 0x81 10 NULL Head Srt Steps: Set srt := head while ( srt->next != NULL) print srt->info // 8 srt := srt->next if (srt->next == NULL) print srt->info end of traversing 0x80 0x81 0x82 False Not Executed Output: 8 Srt 0x80 0x81 Srt
- 11. TRAVERSING 0x80 9 0x82NULL 8 0x81 0x81 10 NULL Head Srt Steps: Set srt := head while ( srt->next != NULL) print srt->info // 9 srt := srt->next if (srt->next = NULL) print srt->info end of traversing 0x80 0x81 0x82 True Output: 8 9 10 Srt 0x80 0x81 0x82 Srt
- 12. OPERATIONS ON DOUBLY LINKED LIST Insertion โข Insert an element at first โข Insert an element at last โข Insert before a given element โข Insert after a given element Deletion โข Delete first element โข Delete last element โข Delete a given element โข Delete before a given element โข Delete after a given element
- 13. INSERT AN ELEMENT AT FIRST prev info NULLprev info nextNULL info next Head Steps- 1. New node (Ptr) prev info next Ptr
- 14. INSERT AN ELEMENT AT FIRST prev info NULLprev info nextinfo next Head data Steps- 1. New node (Ptr) 2. Ptr โ info := data 3. Ptr โ prev := NULL 4. Ptr โ next := NULL Ptr NULL NULL NULL
- 15. INSERT AN ELEMENT AT FIRST prev info NULLprev info nextinfo next Head NULL data Steps- 1. New node (Ptr) 2. Ptr โ Info := data 3. Ptr โ prev := NULL 4. Ptr โ next := NULL 5. Head โ prev := ptr 6. Ptr โ next := head 7. Head := Ptr Ptr NULL NULL Head
- 16. EXAMPLE OF FIRST INSERTION: This is a doubly linked list โฆ. 0x81 8 XX 1 0x81 0x80 5 0x82 Inserting 45 at the first of the list 0x820x810x80 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 X 45 X 0x90 0X900X80
- 17. INSERT AN ELEMENT AT LAST prev info NULLprev info nextNULL info next prev info next srt Ptr Steps- 1. New node (Ptr) Head
- 18. INSERT AN ELEMENT AT LAST prev info NULLprev info nextNULL info next info data next srt Ptr Steps- 1. New node (Ptr) 2. Ptr โ Info := data Head
- 19. INSERT AN ELEMENT AT LAST prev infoprev info nextNULL info next data srt Ptr Steps- 1. New node (Ptr) 2. Ptr โ Info := data 3. Ptr โ prev := NULL 4. Ptr โ next := NULL 5. srt โ next := ptr 6. Ptr โ prev := srt NULL NULL NULL Head
- 20. EXAMPLE OF LAST INSERTION: This is a doubly linked list โฆ. Insert 45 at the last of the list 0x81 8 XX 1 0x81 0x80 5 0x82 After insertion 45 at lastโฆ. 0x820x810x80 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 X 45 X 0x90 0X820X90
- 21. INSERT BEFORE A GIVEN ELEMENT prev info NULLprev info nextprev info next Steps- 1. New Node(Ptr) 2. ptr โinfo = data NULL info next data given element Ptr srttemp Head
- 22. INSERT BEFORE A GIVEN ELEMENT prev info NULLprev info nextinfo next Steps- 1. New Node(Ptr) 2. ptr โinfo = data 3. srt โprev := Ptr 4. temp โnext := Ptr 5. ptr โprev := temp 6. ptr โnext := srt NULL info data given element Ptr srttemp next prev Head
- 23. EXAMPLE INSERT BEFORE A GIVEN ELEMENT: 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 X 36 X 0x90 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 0x90 Inserting 36 before 5โฆ
- 24. EXAMPLE INSERT BEFORE A GIVEN ELEMENT: 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 X 36 X 0x90 0x81 8 XX 1 0x80 5 0x82 0x820x810x80 0x90 Inserting 36 before 5โฆ 0x90
- 25. EXAMPLE INSERT BEFORE A GIVEN ELEMENT: 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 X 36 X 0x90 0x81 8 XX 1 5 0x82 0x820x810x80 0x90 Inserting 36 before 5โฆ 0x90 0x90 0X80 0X81
- 26. SPECIAL CASE: (IF GIVEN ELEMENT IS THE FIRST NODE OF THE LIST) prev info NULLprev info nextprev info nextNULL info next Given element ๏ถ When Head โinfo = given element ๏ In this case it is similar to first insertion โฆ. Head
- 27. INSERT AFTER A GIVEN ELEMENT prev info NULLprev info nextprev info nextNULL info next data given element srt Head Steps- 1. New Node (Ptr) 2. Ptr โ info := data Ptr
- 28. INSERT AFTER A GIVEN ELEMENT prev info NULLinfo nextprev infoNULL info next data given element srt Head Steps- 1. New Node (Ptr) 2. Ptr โ info := data 3. Ptr โ prev := srt 4. Ptr โ next := srt โ next 5. srt โ next โprev := Ptr 6. srt โ next := Ptr Ptr next prev
- 29. EXAMPLE INSERT AFTER A GIVEN ELEMENT: 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 X 10 X 0x90 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 Inserting 10 after 5โฆ 0X820X81
- 30. EXAMPLE INSERT AFTER A GIVEN ELEMENT: 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 X 10 X 0x90 0x81 8 XX 1 0x81 0x80 5 0x820x810x80 Inserting 10 after 5โฆ 0X820X81 0x90
- 31. EXAMPLE INSERT AFTER A GIVEN ELEMENT: 0x81 8 XX 1 0x81 0x80 5 0x82 0x820x810x80 X 10 X 0x90 8 XX 1 0x81 0x80 5 0x820x810x80 Inserting 10 after 5โฆ 0X820X81 0x90 0x90
- 32. SPECIAL CASE: (IF GIVEN ELEMENT IS THE LAST NODE OF THE LIST) prev info NULLprev info nextprev info nextNULL info next Given element ๏ถ When srt โ next = NULL ๏ In this case it is similar to last insertion โฆ. Head srt
- 33. Now Itโs Time for Deletion
- 34. DELETE AN ELEMENT AT FIRST Prev Info NextPrev Info NextNULL Info Next Prev Info NULL Steps- 1. Set head := head->next 2. Set head->prev := NULL Head Head
- 35. DELETE AN ELEMENT AT FIRST Prev Info NextInfo NextNULL Info Next Prev Info NULL Steps- 1. Set head := head->next 2. Set head->prev := NULL Head NULL
- 36. EXAMPLE OF FIRST DELETION: This is a doubly linked list โฆ. Delete the first node.. 0x820x810x80 0x81 8 0x83NULL 1 0x81 0x80 5 0x82 0x82 45 NULL 0x83 Head Head
- 37. EXAMPLE OF FIRST DELETION: After deleting first node 0x820x81 0x81 8 0x83NULL 1 0x81 5 0x82 0x82 45 NULL 0x83 Head NULL 0x80
- 38. DELETE AN ELEMENT AT LAST Prev Info NextPrev Info NextNULL Info Next Prev Info NULL Steps- When srt->next := NULL 1. Set temp->next := NULL Head Temp Srt
- 39. DELETE AN ELEMENT AT LAST Prev InfoPrev Info NextNULL Info Next Prev Info NULL Steps- When srt->next := NULL 1. Set temp->next := NULL Head Temp Srt NULL
- 40. EXAMPLE OF LAST DELETION: This is a doubly linked list โฆ. Delete the last node.. 0x820x810x80 0x81 8 0x83NULL 1 0x81 0x80 5 0x82 0x82 45 NULL 0x83 Head Temp Srt
- 41. EXAMPLE OF LAST DELETION: This is a doubly linked list โฆ. Delete the last node.. 0x820x810x80 0x81 8NULL 1 0x81 0x80 5 0x82 0x82 45 NULL 0x83 Head Temp Srt NULL
- 42. DELETE A NODE OF GIVEN ELEMENT Prev Info NextPrev info NextNULL Info Next Prev Info NULL Head Steps- when srt->info := item srt->next->prev := srt->prev srt->prev->next := srt->next Srt
- 43. EXAMPLE OF DELETION OF A GIVEN ELEMENT: This is a doubly linked list โฆ. Delete the particular node.. Suppose the item is 8 0x820x810x80 0x81 5 0x83NULL 1 0x81 0x80 5 0x82 0x82 45 NULL 0x83 8 Head Srt
- 44. EXAMPLE OF DELETION OF A GIVEN ELEMENT: This is a doubly linked list โฆ. Delete the particular node.. Suppose the item is 8 0x820x810x80 0x80 5 0x83NULL 1 0x81 0x80 5 0x82 0x82 45 NULL 0x83 8 Head Srt
- 45. EXAMPLE OF DELETION OF A GIVEN ELEMENT: After deleting the particular node 0x820x810x80 0x80 5 0x83NULL 1 0x80 5 0x82 0x82 45 NULL 0x83 8 Head 0x82 Srt
- 46. SPECIAL CASES: FOR DELETION OF GIVEN ELEMENT I) If the given element is in the first node, it will be as same as first element delete. II) If the given element is in the last node, it will be as same as last element delete.
- 47. DELETE A NODE AFTER GIVEN ELEMENT Prev Info NextPrev Info NextNULL Info Next Prev Info NULL Steps- when srt->info := item Set srt->next->next->prev := srt srt->next=srt->next->next Head Srt
- 48. EXAMPLE OF DELETION AFTER A GIVEN ELEMENT: This is a doubly linked list โฆ. Delete the particular node.. Suppose the item is 1 0x820x810x80 0x81 8 0x83NULL 0x81 0x80 5 0x82 0x82 45 NULL 0x83 Head 1 Srt
- 49. EXAMPLE OF DELETION AFTER A GIVEN ELEMENT: This is a doubly linked list โฆ. Delete the particular node.. Suppose the item is 1 0x820x810x80 0x80 8 0x83NULL 0x81 0x80 5 0x82 0x82 45 NULL 0x83 Head 1 Srt
- 50. EXAMPLE OF DELETION AFTER A GIVEN ELEMENT: Deleting the particular node after the given element 0x820x810x80 0x80 8 0x83NULL 0x80 5 0x82 0x82 45 NULL 0x83 Head 0x821 Srt
- 51. SPECIAL CASES: FOR DELETION AFTER GIVEN ELEMENT I) If the given element is before the last node , it will be as same as last element delete. II) If the given element is in the last node, it will not be possible. As the next of last node is NULL , it will not delete anything
- 52. DELETE A NODE BEFORE GIVEN ELEMENT Prev Info NextPrev Info NextNULL Info Next Prev Info NULL Steps- when srt->info := item Set srt->prev->prev->next := srt srt->prev:= srt-> prev->prev Head Srt
- 53. EXAMPLE OF DELETION BEFORE A GIVEN ELEMENT: This is a doubly linked list โฆ. Delete the particular node before a given item.. Suppose the item is 9 0x820x810x80 0x81 8 0x83NULL 1 0x81 0x80 5 0x82 0x82 NULL 0x83 Head 9 Srt
- 54. EXAMPLE OF DELETION BEFORE A GIVEN ELEMENT: This is a doubly linked list โฆ. Delete the particular node before a given item.. Suppose the item is 9 0x820x810x80 0x81 8 0x83NULL 1 0x81 0x80 5 0x83 0x82 NULL 0x83 Head 9 Srt
- 55. EXAMPLE OF DELETION BEFORE A GIVEN ELEMENT: After Deleting The Node Before A Given Element 0x820x810x80 0x81 8 0x83NULL 1 0x81 0x80 5 0x83 NULL 0x83 Head 90x81 Srt
- 56. SPECIAL CASES: FOR DELETION AFTER GIVEN ELEMENT I) If the given element is after the first node , it will be as same as first element delete. II) If the given element is in the first node, it will not be possible. As the next of first node is NULL , it will not delete anything
- 57. COMPLEXITY โ FIRST / LAST INSERTION prev info NULLprev info nextNULL info next Head First insertion Last insertion Last
- 58. COMPLEXITY โ INSERTION prev info NULLprev info nextNULL info next Head insertion Last
- 59. COMPLEXITY โ FIRST / LAST DELETION prev info NULLprev info nextNULL info next Head First deletion Last deletion Last
- 60. COMPLEXITY โ DELETION prev info NULLprev info nextNULL info next Head deletion Last
- 61. COMPLEXITY OF DOUBLY LINKED LIST โข Inserting based on the value ( e.g. inserting in a sorted list )- will be O(n). If it is being inserted after or before an existing known node is O(1). โข Deleting an arbitrary value (rather than a node) will indeed be O(n) as it will need to find the value. Deleting a node (when the node is known ) is O(1). โข Inserting to the first or last of the list will always be O(1) - because those are just special cases of the above.
- 62. ADVANTAGES OF DOUBLY LINKED LIST ๏ง Dynamic size ๏ง Ease of insertion/deletion ๏ง A DLL can be traversed in both forward and backward direction. ๏ง The delete operation in DLL is more efficient if pointer to the node to be deleted is given. In singly linked list, to delete a node, pointer to the previous node is needed. To get this previous node, sometimes the list is traversed. In DLL, we can get the previous node using previous pointer.
- 63. DISADVANTAGES OF DOUBLY LINKED LIST ๏ฑ Every node of DLL Require extra space for an previous pointer. ๏ฑ All operations require an extra pointer previous to be maintained. For example, in insertion, we need to modify previous pointers together with next pointers.
- 64. REFERENCES: โข Class lecture โข Stackoverflow.com โข Geekforgeeks.org
- 65. Thank you
Editor's Notes
- Hello good afternoonโฆ.. I am ..... I am here to make a presentation on doubly linked list These are some parts of this presentation
- at first I am going to talk about linked listโฆ What is a linked list?? Why we need to use linked list?? I will tell you something behind the figureโฆ.
- Variables or pointers addresses of a node are contiguous Bt every nodeโs starting address is randomโฆ.not sequential. Nowโฆ look at the memory allocation of arrayโฆ. The addresses are contiguous. So thatโs the difference
- Why linked list?? Well, we can increase the size of the list Bt we can not increase the size of an initialized sized array โฆ. If it is attempted , then index wont be found and cause overflow
- A double way or two way linked list a linked list that every element is linked with its previous and next element through pointers
- To create a doubly linked list.. Firstly a pointer of node type is declared globally โฆ. Say it is โheadโ. And initialized to null, as it points to nothing. Now each time a new element is inserted, a new node is created (here denoted by ptr). Data is stored in the info section of ptr And prev and next pointer initialized to null Now for the first nodeโฆ. Head needs to point the first nodeโฆ. Also for the next insertion the previous node address needs to be storedโฆ Thatโs why temp is used to store the address. Then for all other insertion โฆ We set the next pointer of temp to ptr; And prev pointer of ptr to temp; Update temp to ptr to keep track of the previous node.
- For traversing we start from the head and continue till the next pointer of a node equals to null... And