Question

What is stored in the link field of the last node of a nonempty single linked list?

Short answer

The link field of the last node is null.

Step-by-step solution

Understanding a Singly Linked List

A singly linked list is a data structure consisting of nodes. Each node contains data and a link field that points to the next node in the sequence. The list has a head, which is the starting point.

Identifying the Last Node in the List

In a singly linked list, the last node is identified by the fact that its link field does not point to another node in the list. This node is typically referred to as the tail of the list.

Determining the Contents of the Link Field

The link field of the last node, or tail, of a non-empty singly linked list is set to null (or a null equivalent, such as 'None' in Python). This indicates that there are no more nodes in the list following this one.

Key concepts

Data Structures

Data structures are foundational concepts in computer science. They define how data is stored, organized, and manipulated within a computer. Think of them as the way data is assembled such as arrays, linked lists, stacks, and queues.
Each structure has its own unique way of organizing data to make certain tasks more efficient. For instance, a linked list is ideal for applications where you need quick insertion and deletion. Whereas arrays benefit programs that need fast access to data.
Data structures are essential for optimizing performance in programs. They enable programmers to handle large datasets efficiently, making them crucial in both software development and competitive programming.

Node

A node is a fundamental part of many data structures, including singly linked lists. Picture it as a container that holds part of the data and a connection to another container, forming a chain.
In a linked list, each node contains two primary components:

• Data: This is the value or the information that the node stores.
• Link: A reference or pointer to the next node in the series. This linkage forms the basis of the list.

The concept of nodes is powerful because it enables dynamic memory allocation. This means we can allocate memory as needed, which is more efficient than pre-defining a fixed amount of memory.

Null Pointer

A null pointer is a special value used in programming and data structures. It indicates that a pointer does not point to any valid object or node in the memory.
In the context of a singly linked list, the null pointer is crucial. It is stored in the link field of the last node, known as the tail node. This signifies the end of the list.
Using a null pointer helps prevent errors that might occur when traversing or modifying a linked list. It functions as a safety net to denote that there are no more elements beyond the current node.

Tail Node

The tail node is an essential concept in the structure of a singly linked list. It is the final node in the sequence, effectively marking the end of the list.
Unlike other nodes, the tail node's link field is set to a null pointer. This null value signals that there are no further nodes following the tail.
Managing the tail node is important for operations that involve appending or deleting nodes. An understanding of the tail node helps ensure that your list operates smoothly, preventing errors during list traversal and manipulation.