Question

The __________ points to the first node in a linked list.

Short answer

Answer: head

Step-by-step solution

Understanding Linked Lists

A linked list is a dynamic data structure in which each element (called a node) contains a data part and a reference (or link) to the next node in the sequence. Linked lists use pointers to keep track of the next element in the list. Traversal is done by following these pointers one after the other until the end of the list is reached.

First Node in a Linked List

The first node in a linked list is important because it serves as the entry point for accessing the rest of the list. It is the starting point from which we can traverse the list and access its elements. The term we are looking for that points to the first node is called the __head__.

Recap

In a linked list, the _______ points to the first node in a linked list. The term that fills the blank is called the __head__. The head is important as it serves as the starting point for traversing the list or accessing its elements.

Key concepts

Dynamic Data Structure

A linked list is considered a dynamic data structure because its size is not fixed. Instead, it can grow or shrink as needed during the execution of a program. This flexibility occurs because elements in a linked list, known as nodes, do not need to be stored in contiguous memory blocks. Therefore, linked lists do not allocate memory upfront, unlike static arrays which need a predefined size.

• The advantage is efficient memory usage, especially when the number of elements can change dynamically.
• Another benefit is that linked lists easily support various data structures such as stacks and queues.

On the downside, linked lists may require more memory due to storage of pointers and may have slower access times compared to arrays because elements are accessed sequentially.

Node

In the context of linked lists, a node refers to the building block of this data structure. Each node contains at least two components:

• The 'data part' that stores the actual data or information which can be of any data type.
• The 'link' or 'pointer' that references the next node in the sequence.

This combination of data and pointer(s) is what allows linked lists to form a chain of nodes.
Nodes also introduce the concept of a tail node, which is the last node in the list and contains a pointer to null, signifying the end of the list.
There can also be variations like doubly linked lists, where nodes have pointers to both the next and previous nodes.

Pointers

Pointers are pivotal in linked lists as they create the connections between nodes. In simple terms, a pointer is a variable that holds the memory address of another variable (in this case, another node). This makes it possible to link nodes dynamically.

• Each node contains a pointer that directs to the next node, ensuring the linked list can be traversed sequentially.
• The head pointer is special as it points to the first node of the linked list, allowing access to the entire list.

Without pointers, it would be impossible to create the chain-like structure that defines linked lists. Pointers thus facilitate list traversal, addition, and removal operations.

List Traversal

List traversal in linked lists refers to the process of accessing each node one after another. Starting from the head node, traversal involves following the chain of pointers from node to node until reaching the tail node, which signifies the end of the list as its next pointer is null.
Key points about traversal include:

• Efficiency: While traversal is useful for searching and accessing elements, it can be slow, as each node must be visited sequentially. This can be a drawback for lengthy lists.
• Iteration: Traversal is often implemented using loops (e.g., while loops) which continue until a null pointer is encountered.

Understanding traversal is crucial, as it underlies many operations such as searching for a value or printing the entire list.