Data Structures: Arrays vs Linked Lists
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Questions and Answers

What is a key disadvantage of using arrays for ordered data structures?

  • Dynamic memory allocation
  • Fixed capacity and expensive insertions and deletions at interior positions (correct)
  • Easy to use for all data types
  • Constant-time access to elements

    • In a singly linked list, the last node has a next reference to the first node.

    False

    What is the reference to the first node of a linked list called?

    head

    In a singly linked list, each node stores a reference to the _____ and a reference to the next node.

    <p>element</p> Signup and view all the answers

    Match the following linked list components with their descriptions:

    <p>head = First node of the linked list tail = Last node of the linked list next reference = Pointer to the next node in the sequence size = Count of the total number of nodes in the list</p> Signup and view all the answers

    What do you need to do to add an entry at index i in an array?

    <p>Shift all entries to the right from index i to make space</p> Signup and view all the answers

    Removing an entry from an array does not require shifting any elements.

    <p>False</p> Signup and view all the answers

    What is typically stored in a linked list instance in addition to references to the nodes?

    <p>Tail reference and size</p> Signup and view all the answers

    What does the addFirst algorithm do?

    <p>Adds a new element to the front of the list</p> Signup and view all the answers

    Removing from the tail of a singly linked list is efficient.

    <p>False</p> Signup and view all the answers

    What happens to the size of the list when an element is removed from the head?

    <p>It decreases by one.</p> Signup and view all the answers

    In a circularly linked list, the next reference of the tail node is set to refer back to the ______.

    <p>head</p> Signup and view all the answers

    Match the following operations to their descriptions:

    <p>addLast = Adds an element to the end of the list removeFirst = Removes and returns the first element of the list size = Returns the number of elements in the list isEmpty = Checks if the list is empty</p> Signup and view all the answers

    Which of the following describes a key difference between singly linked lists and circularly linked lists?

    <p>Singly linked lists have a fixed start and end.</p> Signup and view all the answers

    What is a limitation of singly linked lists?

    <p>Cannot traverse backwards</p> Signup and view all the answers

    The algorithm addLast will set the next of the new node to null.

    <p>True</p> Signup and view all the answers

    What does the function last() do in a singly linked list?

    <p>Returns the last element without removing it.</p> Signup and view all the answers

    In a doubly linked list, each node has a reference to both the previous and next nodes.

    <p>True</p> Signup and view all the answers

    What do header and trailer nodes represent in a linked list?

    <p>Sentinels</p> Signup and view all the answers

    In a doubly linked list, each node stores a reference to the _____ node of the list.

    <p>next</p> Signup and view all the answers

    Match the following functions with their descriptions:

    <p>size() = Returns the number of elements in the list isEmpty() = Returns true if the list is empty first() = Returns the first element without removing it addFirst(e) = Adds a new element to the front of the list</p> Signup and view all the answers

    To add an element at the tail of a linked list, what alternate action is performed?

    <p>Add at the head and rotate</p> Signup and view all the answers

    Describe how deletions are managed in a linked list.

    <p>Deletions take place between pairs of existing nodes.</p> Signup and view all the answers

    Adding a new element to a doubly linked list does not require knowledge of the adjacent nodes.

    <p>False</p> Signup and view all the answers

    Study Notes

    Arrays: Advantages and Disadvantages

    • Arrays have a fixed capacity, which can be a limitation.
    • Inserts and deletes at the interior position are expensive due to the shifting of many elements.
    • Arrays allow constant-time access to any element.

    Singly Linked Lists

    • A singly linked list is an alternative to an array-based structure.
    • It consists of nodes, each containing a reference to an object (element) and a reference to the next node.
    • The head node is the first node in the list, and the tail node is the last node.
    • The tail node has a null reference for its next attribute.
    • A singly linked list typically stores a reference to the tail node and the number of nodes (size).

    Insertion at the Head

    • The addFirst(e) algorithm adds a new node at the front of the list.
    • It creates a new node, sets its next reference to the current head, and updates the head reference to point to the new node.
    • The size counter is incremented.

    Insertion at the Tail

    • The addLast(e) algorithm adds a new node at the end of the list.
    • It creates a new node, sets its next reference to null, sets the next reference of the tail node to the new node, and updates the tail reference to point to the new node.
    • The size counter is incremented.

    Removal from the Head

    • The removeFirst() algorithm removes the first node in the list.
    • It checks for an empty list and if not, updates the head reference to point to the second node.
    • If the list is empty after the deletion, the head reference becomes null.
    • The size counter is decremented.

    Removal from the Tail

    • Removing from the tail of a singly linked list is not efficient.
    • There is no constant-time way to update the tail reference to point to the previous node.

    Interface of a Singly Linked List

    • The singly linked list interface defines methods:
      • size(): Returns the number of elements in the list.
      • isEmpty(): Returns true if the list is empty, otherwise false.
      • first(): Returns the first element without removing it.
      • last(): Returns the last element without removing it.
      • addFirst(e): Adds a new element to the front of the list.
      • addLast(e): Adds a new element to the end of the list.
      • removeFirst(): Removes and returns the first element of the list.

    Circularly Linked Lists

    • A circularly linked list is a singly linked list where the next reference of the tail node points to the head.
    • Data is viewed as cyclic with no fixed beginning or end.
    • The tail reference is used for traversal and manipulation instead of the head reference.
    • The list is rotated by advancing the tail reference to the next node.
    • Insertion at the head or tail is similar to a regular singly linked list, with an additional rotation step for tail insertion.

    Doubly Linked Lists

    • Doubly linked lists overcome limitations of singly linked lists regarding efficient deletion of the tail node or a node from an interior position.
    • Each node in a doubly linked list stores a reference to both the previous and next nodes.
    • Traversal can be performed both forward and backward.

    Header and Trailer Sentinels

    • Header and trailer nodes (sentinels) are special nodes added to the beginning and end of the list.
    • They do not store elements.
    • These sentinels help simplify insertion and deletion operations.

    Insertion in Doubly Linked Lists

    • Insertion happens between two existing nodes.
    • A new node is created and linked between the existing nodes by updating their previous and next references.

    Deletion in Doubly Linked Lists

    • Deletion also happens between two existing nodes.
    • The node to be deleted is removed by updating the previous and next references of its neighboring nodes.

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    ds05linkedlists.pdf

    Description

    This quiz explores the advantages and disadvantages of arrays compared to singly linked lists. It covers concepts such as fixed capacity, insertion algorithms, and node references. Test your understanding of these fundamental data structures in computer science.

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