LINKED LIST

LINKED LIST

A linked list is a linear data structure that consists of a sequence of elements, called nodes, each of which contains two components: the data part and a reference (or pointer) to the next node in the sequence. The last node points to `null`, signifying the end of the list.

 

Why Use Linked Lists?

Linked lists offer several advantages over arrays, particularly in scenarios where:

1. Dynamic Size: Unlike arrays, linked lists do not require a predefined size, allowing them to grow and shrink dynamically as elements are added or removed.
2. Efficient Insertions/Deletions: Linked lists enable easy insertion and deletion of elements without the need to shift elements, as is necessary in arrays. This is because elements in a linked list are not stored in contiguous memory locations.
3. Memory Allocation: Linked lists allocate memory as needed, making them memory-efficient, especially for unpredictable workloads.

 

Types of Linked Lists

1. Linked lists come in various forms, each with its own characteristics:
2. Singly Linked List: Each node points to the next node, with the last node pointing to `null`.
3. Doubly Linked List: Each node contains pointers to both the next and the previous nodes, allowing traversal in both directions.
4. Circular Singly Linked List: The last node points back to the first node, forming a circle.
5. Circular Doubly Linked List: Similar to the doubly linked list, but with the last node pointing back to the first node and the first node pointing to the last node.

 

Advantages of Linked Lists

1. Dynamic Data Structure: The size of a linked list can vary according to the needs of the program.
2. Easy Insertion/Deletion: No need to shift elements as in arrays.
3. Memory Efficient: Memory is allocated only as needed.

 

Disadvantages of Linked Lists

1. Memory Usage: Linked lists require extra memory for storing pointers.
2. Traversal: Accessing elements is slower since nodes must be traversed sequentially.
3. Reverse Traversal: Difficult in singly linked lists; easier in doubly linked lists but at the cost of additional memory.

 

Applications of Linked Lists

1. Polynomial Representation: Useful for operations on polynomials.
2. Sparse Matrices: Can represent sparse matrices efficiently.
3. Dynamic Memory Allocation: Used in dynamic memory allocation systems.
4. Data Structures: Implementation of stacks, queues, trees, and graphs.

 

Operations on Linked Lists

1. Insertion: Adding a new node.
2. Deletion: Removing a node.
3. Display: Showing the elements of the list.
4. Search: Finding a node with a specific key.

 

Complexity of Linked Lists

1. Time Complexity: Insertion and deletion operations have O(1) time complexity, while search operations have O(n) time complexity.
2. Space Complexity: The space complexity for storing a linked list is O(n), where n is the number of nodes.