ListNode

ListNode is a fundamental data structure commonly used in computer science, particularly in the context of linked lists. It represents a single node within a linked list, which is a linear data structure consisting of nodes where each node contains data and a reference (or pointer) to the next node in the sequence.

The basic structure of a ListNode typically includes two main components:

1. Data: This is the value or information stored in the node. The type of data can vary depending on the application, such as integers, strings, or more complex objects.

2. Next: This is a reference to the next ListNode in the sequence. In some implementations, it may be null or None to indicate the end of the list.

ListNodes are used to build linked lists, which can be singly linked (each node points to the next node), doubly linked (each node points to both the next and the previous nodes), or circular (the last node points back to the first node). The use of ListNodes allows for dynamic memory allocation and efficient insertion and deletion operations, making linked lists a versatile data structure for various applications, such as implementing stacks, queues, and other abstract data types.

In the context of algorithms and data structures, ListNodes are often used in problems related to reversing a linked list, detecting cycles, merging two sorted linked lists, and finding the middle of a linked list. They are also commonly used in interview questions to assess a candidate's understanding of linked list manipulation and traversal techniques.