1. Linked List Improvements

2. BigO's What is BigO for our basic linked list operations? O(1) O(n)
InsertStart
Insert at middle
InsertEnd
Retrieve First Value
Retrieve Middle Value
Remove From End
Remove From Beginning
Get Length
 O(1)
O(n)
 O(n)
  O(1)
O(n) 
 O(1) 

3. Linked List Gripes Issues with basic linked list:
No easy way to get length
No easy way to put something at the end

4. Length Keep track of length of list listSize() now O(1)
Increment on any insert
Decrement on removal
listSize() now O(1)

5. Length Side Benefit Cheap list size can simplify other algorithms
Error check early

6. InsertEnd Want to efficiently implement: InsertEnd(int value)
What do we need?

7. Tail Pointer
Tail pointer
Always points to last element

8. InsertEnd InsertEnd(value)
Node* newNode = new Node(value) tail->next = newNode tail = newNode length++

9. InsertEnd InsertEnd(value)
Node* newNode = new Node(value) tail->next = newNode tail = newNode length++

10. InsertEnd InsertEnd(value)
Node* newNode = new Node(value) tail->next = newNode tail = newNode length++

11. InsertEnd InsertEnd(value)
Node* newNode = new Node(value) tail->next = newNode tail = newNode length++

12. InsertEnd Special case : insertEnd on empty list InsertEnd(value)
Pass off to insertStart
InsertEnd(value)
If length == 0 insertStart(value) return
Node* newNode = new Node(value) tail->next = newNode tail = newNode length++

13. Tail Issues InsertEnd(value) now O(1)
But need to worry about tail in other situations
InsertStart on empty list 
InsertAt on last node
RemoveAt on last node

14. Tail Issues
Example: insertStart on empty list

15. Tail Issues Example Removing at current tail removeAt(2) called
Found current and nodeToRemove

16. Tail Issues Example Removing at current tail removeAt(2) called
Removed node from list

17. Tail Issues Example Removing at current tail removeAt(2) called
Deleted from memory

18. Tail Issues Example Removing at current tail removeAt(2) called
We have a new tail!

19. BigO's What is BigO for our improved linked list operations?
With length & tail
Get Length
Insert Start
Insert at
InsertEnd
Retrieve
Retrieve
Remove
Remove
middle
First / L
ast
Middle
Beginning
End
Value
Value

20. BigO's What is BigO for our improved linked list operations? O(1) O(1)
With length & tail
Get Length
Insert Start
Insert at
InsertEnd
Retrieve
Retrieve
Remove
Remove
middle
First / L
ast
Middle
Beginning
End
Value
Value
O(1)
O(1)
O(n)
O(1)
O(1)
O(n)
O(1)
O(n)

21. Linked List & Memory

22. Memory Management Destructor needs to free allocated nodes
Must delete each individually

23. Destruct
~LinkedList() Node* temp = head while head is not null head = head->next delete temp temp = head

24. Destruct
~LinkedList() Node* temp = head while head is not null head = head->next delete temp temp = head

25. Destruct
~LinkedList() Node* temp = head while head is not null head = head->next delete temp temp = head

26. Destruct
~LinkedList() Node* temp = head while head is not null head = head->next delete temp temp = head

27. Destruct Alternative Destructor made simple:
~LinkedList() while head is not null removeFirst

28. Copy Constructor Want a deep copy
Whole new list of nodes with identical data, in same order
Length, head and tail set correctly
foreach node in other get node's value insert value at end

29. Copy Constructor Want a deep copy
Whole new list of nodes with identical data, in same order
Length, head and tail set correctly
foreach node in other get node's value insert value at end

30. Copy Constructor Want a deep copy
Whole new list of nodes with identical data, in same order
Length, head and tail set correctly
foreach node in other get node's value insert value at end

31. Copy Constructor Want a deep copy
Whole new list of nodes with identical data, in same order
Length, head and tail set correctly
foreach node in other get node's value insert value at end

32. Copy Constructor Want a deep copy
Whole new list of nodes with identical data, in same order
Length, head and tail set correctly
foreach node in other get node's value insert value at end …

33. Assignment Operator myList = other Delete all nodes
Copy nodes from other