Beginner · 5h 40m · 20 lessons
Data Structures, Gently
Meet the everyday containers that hold your data — and learn when to reach for each one.
What you'll learn
- ✦Explain what a data structure is and why the right one makes code faster and clearer
- ✦Use arrays and lists by index, and decide when jumping to a position beats searching by value
- ✦Predict what a stack (LIFO) or a queue (FIFO) hands back next, and name a real problem each one solves
- ✦Use a hash map or a set to look things up by key and remove duplicates in one pass
- ✦Describe trees and graphs, and decide which one fits branching or networked data
- ✦Read Big-O labels like O(1), O(n) and O(n²), and compare the cost of common operations
- ✦Choose a sensible data structure for a new problem with a short checklist
- ✦Explain your choice of data structure in an interview or code review: the operation it makes cheap
- ✦Spot stacks, queues and recursion in real apps, and iterate collections with for-each, map, filter and reduce
- ✦Weigh time against space and mutable against immutable, and name the algorithms to learn next
Part of these career paths
- CS Foundations path · course 3 of 5
Certification projects
Build 4 projects to earn your certificate
Hands-on work that proves you can apply what you learned — part of the certificate requirements.
Syllabus
Module 1 · 52m
Why structures matter Free
What you'll be able to do
- Can explain a data structure as a way of arranging data, and tell it apart from the algorithm that uses it
- Can predict how a list scan and a set lookup behave as the data grows from hundreds to lakhs
- Can find a program's hot path by counting how often each operation runs
Module 2 · 1h 15m
Lists, stacks & queues Locked
What you'll be able to do
- Can read and change list items by index, counting from 0, and count the items an insert shifts
- Can trace pushes and pops, or enqueues and dequeues, and say what comes out next
- Can tell a newest-first (stack) problem from a first-come, first-served (queue) problem
- Can choose between an array and a linked list from the operations a job needs
Module 3 · 56m
Maps & sets Locked
What you'll be able to do
- Can store and read values in a hash map by key, and predict what a repeated or missing key does
- Can use a set to remove duplicates and answer 'have I seen this?' in one pass
- Can pick a map for counting and a set for membership in a new problem
Module 4 · 1h 8m
Trees, graphs & cost Locked
What you'll be able to do
- Can name the parts of a tree and trace a search in a binary search tree
- Can tell a graph from a tree and find the fewest hops between two nodes
- Can read Big-O labels and work out a label by doubling the input
- Can pick a structure for a new problem with a short checklist and explain why
Module 5 · 45m
Structures at work Locked
What you'll be able to do
- Can spot stacks and queues in real features and trace what undo or Back does
- Can trace a small recursive function on nested data and name its base case
- Can choose for-each, map, filter or reduce and trace a chain of them by hand
Module 6 · 44m
Picking & measuring Locked
What you'll be able to do
- Can weigh memory against time, and work out what a cache saves and what it costs
- Can predict when shared mutable data changes under you, and make a real copy
- Can tell a data structure from an algorithm and name the algorithms to learn next