Competitive Programmer's Handbook (opens provider site in a new tab)
Antti Laaksonen's concise handbook. The gateway into competitive programming.
Data Structures & Algorithms
Core structures, complexity, and problem-solving — for interviews and for better code.
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16 picks · 11 free · 14 providers · curated by Rowland Kuru
Editor's intro
Editor's intro
Data structures and algorithms are the part of computer science that shows up in technical interviews, but they matter well beyond that: knowing when a hash map beats a list, or why a loop is quietly quadratic, changes how you write everyday code. This feed mixes university courses, practice platforms, and a few well-chosen books.
Pick one language you already know well and do everything in it. Start with a structured course so you meet the core structures in a sensible order, then practise problems steadily — a few a week beats a cram. Intermediate resources focus on patterns and interview prep; advanced ones are for competitive programming and algorithm design proper.
Start here
Algorithms, Part I (Princeton)
Princeton's Algorithms, Part I, taught by Robert Sedgewick and Kevin Wayne, is free on Coursera and remains one of the best algorithms courses ever recorded. It focuses on implementing each structure correctly and analyzing its performance, with programming assignments graded by an autograder that's famously strict about both correctness and efficiency. The course uses Java, but the ideas transfer directly. If you finish Part I and its assignments, you'll understand the fundamentals better than most working developers.
This week added
CSES Problem Set (opens provider site in a new tab)
Three hundred carefully ordered problems. Finishing the early sections is serious evidence of skill.
All picks
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Beginner · 6
Arrays, linked lists, stacks, queues, hash tables, sorting, and Big O. Do everything in one language you know.
Algorithms (opens provider site in a new tab)
A gentle, visual introduction to searching, sorting, recursion, and graphs.
Free
CS50x: Introduction to Computer Science (opens provider site in a new tab)
Builds arrays, linked lists, hash tables, and trees in C. Superb foundations for everything else.
Free Certificate optional
VisuAlgo (opens provider site in a new tab)
Animations of every classic data structure and algorithm. Use it whenever a diagram would help.
Free
Grokking Algorithms, 2nd Edition (opens provider site in a new tab)
Illustrated and friendly. The right book if algorithm textbooks have intimidated you before.
Paid
JavaScript Algorithms and Data Structures Masterclass (opens partner site in a new tab)
Colt Steele's approachable walk through Big O and problem-solving patterns, in JavaScript.
Paid 30-day refund Partner
Learn Data Structures and Algorithms with Python (opens partner site in a new tab)
Implements the core structures in Python step by step. Good for learners who learn by typing.
Paid Partner
Intermediate · 5
Trees, graphs, dynamic programming, and the problem patterns that show up in technical interviews.
Abdul Bari — Algorithms (opens provider site in a new tab)
Whiteboard explanations of dynamic programming, graphs, and complexity that many find clearer than textbooks.
Free
Introduction to Algorithms (6.006) (opens provider site in a new tab)
MIT's core algorithms course with full lectures and problem sets. More mathematical than most.
Free
LeetCode (opens provider site in a new tab)
The standard practice platform. Work from a curated list rather than grinding problems at random.
Free Premium optional
NeetCode Roadmap (opens provider site in a new tab)
A curated problem list grouped by pattern, with free video solutions. Efficient interview prep.
Free Some courses paid
Algorithms Specialization (Stanford) (opens partner site in a new tab)
Tim Roughgarden's proof-driven course. Teaches you to reason about algorithms, not memorize them.
Paid Financial aid available Partner
Advanced · 4
Algorithm design and proof, competitive programming, and the textbooks specialists use.
Algorithms (Jeff Erickson) (opens provider site in a new tab)
A full university textbook, free. Exceptionally clear on recursion, dynamic programming, and graphs.
Free Free PDF
Competitive Programmer's Handbook (opens provider site in a new tab)
Antti Laaksonen's concise handbook. The gateway into competitive programming.
Free Free PDF New
CSES Problem Set (opens provider site in a new tab)
Three hundred carefully ordered problems. Finishing the early sections is serious evidence of skill.
Free New
The Algorithm Design Manual (opens provider site in a new tab)
Skiena's practical catalogue of problems and war stories. The book for applying algorithms at work.
Paid