About Algos.Guru

What Is Algos.Guru?

Algos.Guru is a free, open-source resource designed to help software engineers systematically prepare for coding interviews at top technology companies. We provide a curated collection of LeetCode-style problems organized by difficulty and algorithm type, each accompanied by a complete Java solution, a clear approach explanation, and Big-O time and space complexity analysis.

Unlike raw problem lists, every solution on Algos.Guru is annotated with the reasoning behind the approach — not just what the code does, but why that strategy works and how to recognize similar patterns in new problems.

Who Is This For?

Interview candidates preparing for technical interviews at Google, Meta, Amazon, Apple, Netflix, Microsoft, and other top companies
Computer science students looking to strengthen their understanding of fundamental data structures and algorithms
Self-taught developers who want structured practice with classic algorithm patterns
Engineers switching roles who need to refresh their DSA skills efficiently

What Makes This Different?

There are many LeetCode solution sites on the internet. Here is what Algos.Guru focuses on:

Curated, not exhaustive — We deliberately pick problems that teach the most important patterns, rather than listing thousands of problems. Quality over quantity means you can focus on what actually matters in interviews.
Approach-first explanations — Every problem includes a concise approach description that explains the strategy before showing code. This helps you build pattern recognition, which is far more valuable than memorizing solutions.
Organized by algorithm type — Problems are tagged by their core technique (Two Pointers, Sliding Window, Binary Search, BFS/DFS, Dynamic Programming, etc.) so you can practice one pattern at a time.
Complexity analysis included — Every solution shows the time and space complexity, helping you reason about trade-offs during interviews.
Difficulty progression — Start with Easy problems to build fundamentals, advance to Medium for the bulk of interview patterns, and tackle Hard problems for the most competitive positions.

Topics Covered

Our problem collection spans the most important algorithm and data structure categories tested in coding interviews:

Arrays & Strings

Hash Maps & Sets

Two Pointers

Sliding Window

Binary Search

Linked Lists

Stacks & Queues

Trees & Graphs

BFS & DFS

Dynamic Programming

Backtracking

Heaps & Priority Queues

Tries

Topological Sort

Bit Manipulation

Math & Design

How Each Problem Is Structured

Every problem on Algos.Guru follows a consistent format to maximize your learning:

Problem Statement — A clear description of the problem, exactly as you would see it in an interview or on LeetCode.
Constraints — Input size limits and edge cases to consider.
Examples — Concrete input/output examples with explanations to clarify the expected behavior.
Approach — A concise explanation of the strategy before any code. This is the most important section — it teaches you how to think about the problem.
Java Solution — A clean, well-structured implementation you can study and adapt.
Complexity Analysis — Time and space complexity with Big-O notation, so you understand the efficiency trade-offs.

How to Use This Resource Effectively

To get the most out of Algos.Guru, we recommend the following approach:

Start with one topic at a time. Use the type filter to focus on a single algorithm pattern (e.g., "Sliding Window" or "Binary Search"). Solve 3-5 problems in that category before moving on.
Read the approach before the code. Try to understand the strategy first. Then attempt to write the solution yourself before checking ours.
Track your progress. Use the "Mark Solved" feature to track which problems you have completed. Aim to solve problems across all three difficulty levels.
Revisit after a week. Spaced repetition is powerful. Come back to previously solved problems and try to solve them from scratch.
Focus on patterns, not memorization. The goal is to recognize that a new problem is a variation of a known pattern, not to memorize every solution.

Open Source

Algos.Guru is open source. The full source code — including all Java solutions, the web application, and the build tooling — is available on GitHub. Contributions, bug reports, and problem suggestions are welcome.

Support

Algos.Guru is free to use and will remain free. If you find it helpful, you can support the project through:

Buy Me a Coffee — one-time tips

Your support helps add more problems, improve explanations, and keep the site running.