Marco AlvarezDepartment of Computer Science and Statistics

University of Rhode Island

CSC 212: Data Structures and AbstractionsLinked Lists

Spring 2019

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!3https://aidemos.microsoft.com/

Linked Lists

Arrays‣ Think about making insertions efficiently

✓ what is the cost? (rear, front, middle)

‣ Think about making deletions efficiently✓ what is the cost?

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ptr

Linked Lists‣ Collections of sequential elements stored at non-contiguous locations

‣ Nodes are connected by links✓ every node keeps a pointer to the next node

‣ Can grow and shrink dynamically

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Singly Linked List

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Head Tail

NULL pointer

data data data data

next next next next

Operations on Linked Lists‣ Linked lists are just collections of sequential data

✓ can insert 1 or more elements- front, end, by index, by value (sorted lists)

✓ can delete 1 or more elements- front, end, by index, by value

✓ can search for a specific element✓ can get an element at a given index✓ can traverse the list

- visit all nodes and perform an operation (e.g. print or destroy)

✓ …

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Implementing a Singly Linked List

Linked lists in C++‣ Need to review:

✓ C++ Classes✓ Pointers

- NULL pointers

✓ Dynamic Memory Allocation- new- delete

✓ Pointers and Classes- dot notation (.)- arrow notation (->)

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5class Node { private: int data; Node *next; // add private data/methods // ... public: Node(int d); ~Node(); // add public methods // ... friend class List; }; !12

class List { private: Node *head; Node *tail; // all private data/methods // ... public: List(); ~List(); // all public methods // ... };

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Head Tail

NULL pointer

Append (insert at end)

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Prepend (insert at front)

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Insert by index

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Delete at front

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Delete at end

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Delete by value

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Delete by index

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Get

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Search

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Destroy (freeing a linked list)

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Traversing a linked list‣ Using a for loop

‣ Using recursion

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Circular Singly Linked List

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Head Tail

73 1

Doubly Linked List

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Head Tail

NULL pointerNULL pointer

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Circular Doubly Linked List

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Head Tail

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