TLDR;
This video serves as an introductory guide to linked lists, contrasting them with arrays and explaining their structure, advantages, and real-world applications. It covers the fundamental concepts of linked lists, including their non-contiguous memory allocation, dynamic sizing, and the use of pointers for traversal. The video also explains how to define and manipulate linked lists in both C++ and Java, including converting arrays to linked lists, traversing linked lists, and determining their length.
- Linked lists are dynamic data structures that can grow or shrink in size, unlike arrays.
- Elements in a linked list are not stored in contiguous memory locations.
- Each element in a linked list contains data and a pointer to the next element.
- Linked lists are used in stacks, queues, and browser navigation.
- The video provides code examples in both C++ and Java.
Introduction to Linked Lists [0:03]
The lecture introduces the concept of linked lists as a data structure that, unlike arrays, can dynamically increase or decrease in size. Arrays have a fixed size and store elements in contiguous memory locations, making it impossible to add elements beyond the defined size. Linked lists, however, do not have this limitation.
Linked List Structure and Memory Allocation [2:36]
Linked lists store elements in a non-contiguous manner in the heap memory. Each element, whether it's an integer, double, or another data type, is stored along with a pointer to the next element in the list. This structure allows for dynamic resizing, as new elements can be added anywhere in the heap memory without needing adjacent space. Traversal through a linked list is achieved by following these pointers from one element to the next, starting from the head, which is the first element in the list, and ending at the tail, which points to null.
Advantages and Use Cases of Linked Lists [5:14]
The primary advantage of linked lists over arrays is their ability to dynamically change size. This makes them suitable for applications like stacks and queues, where the size of the data structure needs to vary. In real-world scenarios, linked lists are used in browser navigation to manage the history of visited pages, allowing users to go back and forward.
Data Structures: Structs, Classes, and Self-Defined Objects [13:18]
To implement linked lists, it's essential to understand structs and classes, which are used to create self-defined data types. In C++, a struct or class is defined to hold both the data and a pointer to the next node. The new keyword is used to allocate memory for a new node, and a constructor is used to initialise the node's data and next pointer. While structs and classes can be used interchangeably, classes offer object-oriented programming concepts like abstraction and encapsulation.
Implementing Linked Lists in Java [24:12]
In Java, linked lists are implemented using classes, similar to C++, but without the concept of pointers. Instead, object references are used. The key differences in Java code include the absence of pointers, the use of . to access class members, and the use of null instead of null pointer. The video demonstrates how easily C++ code can be converted to Java by removing pointers and making these minor adjustments.
Memory Space Considerations [26:28]
The memory space occupied by a linked list depends on the system architecture (32-bit or 64-bit) and the data types being stored. For example, in a 32-bit system, an integer and a pointer each take up 4 bytes, resulting in a total of 8 bytes per node. In a 64-bit system, a pointer takes up 8 bytes, increasing the total memory per node to 12 bytes.
Converting an Array to a Linked List [28:03]
The video explains the process of converting an array into a linked list. The first element of the array becomes the head of the linked list. A mover variable is used to traverse the array, creating new nodes for each element and linking them together. The mover is updated to point to the newly created node, ensuring the linked list is properly connected. The function returns the head of the linked list, which serves as the starting point for traversal.
Traversal in a Linked List [37:21]
Traversal involves visiting each node in the linked list, starting from the head. A temporary variable is used to iterate through the list without tampering with the head. The data in each node is accessed and processed, and the temporary variable is moved to the next node until the end of the list is reached (null).
Finding the Length of a Linked List [40:13]
To find the length, a counter is initialised to zero. The list is traversed, and the counter is incremented for each node visited. The final count represents the length of the linked list.
Searching in a Linked List [42:01]
Searching involves traversing the list to check if a given element is present. Each node's data is compared to the target value. If a match is found, the function returns true; otherwise, it continues until the end of the list. If the element is not found, the function returns false. The time complexity for searching is O(n) in the worst case.