CodeBlanks Logo Icon CodeBlanks
Login Register

What is a linked list?

Nodes link to the next node with a pointer.

What is a linked list?

A linked list is a data structure where each node contains data and a pointer to the next node. Elements are not contiguous in memory.

Access in a linked list is O(n) because you must traverse from the start. However, insertion and deletion are O(1) (at the head).

Node definition

A node has two fields: data (the value) and next (pointer to the next node). The last node's next is None.

Nodes are linked to form a chain. The first node is the head and the whole list is accessed from there.

Practice Create node

Write make_node(data). Return {'data': data, 'next': None}. Print 5 with print(make_node(5)['data']).

Starter code

solution.py
def make_node(data):
    # Create node

Sample solution

solution.py
def make_node(data):
    # Create node
    return {'data': data, 'next': None}
print(make_node(5)['data'])

Expected output

5

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 How are elements in a linked list in memory?

  • In a matrix
  • Scattered, linked by pointers Correct answer
  • Sorted
  • Contiguous

Explanation: Scattered, linked by pointers.

2 Node field

Question 
The node's next pointer is ____.
Answer 
The node's next pointer is next.

Explanation: next is right.

3 What is a linked list: match the terms

Term Meaning
Node data + next
head First node
next Pointer
None Last node

All lessons in Beginner

1 What is an algorithm?

  1. Algorithm definition
  2. Algorithm properties
  3. Pseudocode
  4. Summary - Algorithm concept

2 Big-O notation

  1. Time complexity
  2. Big-O definition
  3. Comparing complexities
  4. Summary - Big-O

3 Array

  1. What is an array?
  2. Array access
  3. Looping over an array
  4. Summary - Arrays

4 Linear search

  1. Linear search idea
  2. Implementing search
  3. Best and worst case
  4. Summary - Linear search

5 Search project

  1. Project: Overview
  2. Grades array setup
  3. Search function
  4. Print the result

6 Bubble sort

  1. Bubble sort idea
  2. One pass
  3. Full sort
  4. Summary - Bubble sort

7 Selection sort

  1. Selection sort idea
  2. Finding the minimum
  3. Swapping
  4. Summary - Selection sort

8 Insertion sort

  1. Insertion sort idea
  2. Shifting
  3. Placement
  4. Summary - Insertion sort

9 Sorting project

  1. Project: Overview
  2. Price array
  3. Apply sorting
  4. Print the result

10 Recursion basics

  1. What is recursion?
  2. Base case
  3. Recursive step
  4. Summary - Recursion

11 Fibonacci

  1. Fibonacci sequence
  2. Recursive Fibonacci
  3. Call tree
  4. Summary - Fibonacci

12 Factorial

  1. Factorial definition
  2. Recursive factorial
  3. Choosing the base case
  4. Summary - Factorial

13 Recursion project

  1. Project: Overview
  2. Recursive power
  3. Combination
  4. Print the results

14 Binary search

  1. Binary search idea
  2. Left right pointers
  3. Base case
  4. Summary - Binary search

15 Linked list

  1. What is a linked list?
  2. Node definition
  3. Traversing the list
  4. Summary - Linked list

16 Stack

  1. What is a stack?
  2. Push and pop
  3. Peek and is_empty
  4. Summary - Stack

17 Queue

  1. What is a queue?
  2. Enqueue and dequeue
  3. Front and back
  4. Summary - Queue

18 Hash table

  1. What is a hash table?
  2. Hash function
  3. Collision
  4. Summary - Hash table

19 Set

  1. What is a set?
  2. Add and lookup
  3. Intersection and union
  4. Summary - Set

20 Beginner final

  1. Challenge 1
  2. Challenge 2
  3. Challenge 3
  4. Challenge 4