Linked List in C++: Flexible Memory

A Linked List in C++ is a linear data structure where elements are not stored in contiguous memory locations. Instead, each element is a separate object called a Node. These nodes are linked together using pointers. Unlike arrays, a Linked List in C++ can grow or shrink in size during execution, making it the preferred choice when the number of elements is unknown or frequently changing.

1. Anatomy of a Node

In a Linked List in C++, a node is typically a struct or class. It contains two parts: the Data (which stores the actual value) and the Next Pointer (which stores the memory address of the following node). The list begins at a special pointer called the Head, and the last node's pointer is set to nullptr to signal the end of the chain.

Feature Description
AllocationDynamic (happens at runtime via 'new').
InsertionFast $O(1)$ if the position is known.
SearchSequential $O(n)$; no random access.

2. Basic Operations

Manipulating a Linked List in C++ requires careful pointer management. To insert a node, you update the pointer of the previous node to point to the new one. To delete, you bypass the target node by pointing its predecessor to its successor. Because Linked Lists in C++ don't require shifting elements (like arrays do), insertions and deletions are highly efficient once you reach the target location.

3. Types of Linked Lists

There are several variations of Linked Lists in C++:

  • Singly Linked: Nodes point only to the next node.
  • Doubly Linked: Nodes point to both the next and the previous nodes.
  • Circular: The last node points back to the first node.
While the STL provides a std::list (doubly linked), implementing your own is a classic way to master pointer logic.

Practice MCQs on Linked Lists

1. What does the last node of a Singly Linked List point to?
A) Head | B) nullptr | C) Itself

2. Which of the following is an advantage of Linked Lists over Arrays?
A) Faster access | B) Dynamic size | C) Less memory per element

3. What is the time complexity to search for an element in a Linked List?
A) O(1) | B) O(log n) | C) O(n)