Introduction

A linked list is a linear data structure where elements, called nodes, are connected using pointers. Unlike arrays, where elements are stored in contiguous memory locations, linked lists store elements anywhere in memory and link them together with references.

Key Components of a Linked List

1. Node: Each element in a linked list. A node typically contains:
2. Data: The value or information the node holds.
3. Next: A pointer or reference to the next node in the list.
4. Head: The first node in the linked list. The head acts as the entry point to the list.
5. Null: The last node’s next pointer points to null, indicating the end of the list.

Why Use Linked Lists?

Linked lists have several advantages over arrays, including:

1. Dynamic Size: Unlike arrays, linked lists do not require a predefined size. They grow and shrink as needed.
2. Efficient Insertions and Deletions: Adding or removing elements is faster because there’s no need to shift elements, as in arrays.
3. Memory Utilization: Linked lists can use non-contiguous memory, making them suitable for systems with fragmented memory.

Types of Linked lists

1. Singly Linked List:

Each node has a single pointer to the next node. Traversal is one-directional, starting from the head.

2. Doubly Linked List:

Each node has two pointers: one to the next node and another to the previous node. Traversal can be done in both directions.

3. Circular Linked List: The last node points back to the head, forming a circle. Can be singly or doubly linked.

Essential Linked List Techniques for Problem-Solving

1. Dummy Node Technique

A dummy node simplifies linked list modifications by providing a placeholder node at the beginning. This technique helps avoid edge cases when modifying the head node.

2. Two-Pointer Technique

Using two pointers (fast and slow) allows efficient traversal with O(N) complexity. This technique is useful for finding the middle node, detecting cycles, and finding the nth node from the end.

3. Cycle Detection (Floyd’s Algorithm)

If a linked list has a cycle, it can cause infinite loops. Floyd’s algorithm (also called the Tortoise and Hare algorithm) efficiently detects cycles using two pointers.

Linked List or Array, which one should be used, and when?

Here is the time complexity between the linked list and array.

From this comparison, we can draw the following conclusions:

1. If frequent node additions or deletions are required, a linked list may be a better choice.
2. If frequent access to elements by index is needed, an array could be a more efficient option than a linked list.