# Interview prep

> Interview prep

Canonical: https://learn.significanthobbies.com/learning/interview-prep

The "Apply" half of the Concept → Drill → Build → Review → **Apply** loop. Pairs with the in-app `/practice` tab.

A breadth-first checklist of what SWE interviews actually test. Walk every row, decide whether you can already explain it to a duck in three sentences. Anything you can't → FSRS queue in `/practice`.

For depth, follow the linked roadmap or canonical source. This page deliberately does not re-author content covered in the dedicated docs.

Source layout adapted from Atul Kumar's [Interview Roadmap sheet](https://www.linkedin.com/in/atul-kumar-58727488/).

| Category | What it covers | Where to learn it |
|---|---|---|
| **Data structures** | Arrays, linked lists, queues, stacks, hash tables, graphs, Bloom filters, trees (binary, BST, B-trees, red-black), heaps, disjoint sets | [MIT 6.006 (OCW)](https://ocw.mit.edu/courses/6-006-introduction-to-algorithms-spring-2020/) · [NeetCode 150 roadmap](https://neetcode.io/roadmap) · in-app `/learn` → DSA |
| **Mathematics** | Probability, statistics, common series | [Khan Academy — Prob & Stats](https://www.khanacademy.org/math/statistics-probability) · [3Blue1Brown — Linear Algebra](https://www.3blue1brown.com/topics/linear-algebra) · in-app `/learn` → Math roadmaps |
| **Algorithmic concepts** | Time & space complexity, master theorem, recurrences | [Big-O cheat sheet](https://www.bigocheatsheet.com/) · [MIT 6.006 lecture 2](https://ocw.mit.edu/courses/6-006-introduction-to-algorithms-spring-2020/) |
| **Algorithms** | Sorting, divide & conquer, DP (1-D and 2-D), greedy, backtracking, NP-complete classes, randomized algorithms | [NeetCode roadmap](https://neetcode.io/roadmap) · [Algorithms (Dasgupta et al.) — free PDF](https://people.eecs.berkeley.edu/~vazirani/algorithms.html) · [CPH (Laaksonen) — free PDF](https://cses.fi/book/book.pdf) |
| **Operating systems** | Process scheduling, sync & deadlocks, memory mgmt, file systems, threading vs processes | [OSTEP (Arpaci-Dusseaus)](https://pages.cs.wisc.edu/~remzi/OSTEP/) · [MIT 6.1810 xv6 labs](https://pdos.csail.mit.edu/6.1810/) · [SE Landscape](https://learn.significanthobbies.com/learning/swe-landscape) |
| **Databases** | Relational algebra, schema design, SQL | [Use The Index, Luke](https://use-the-index-luke.com/) · [SQLBolt](https://sqlbolt.com/) · [DB book](https://www.db-book.com/) |
| **Database use** | ACID, BASE, CAP, partitioning, sharding, indexing, replication, transactions | [CMU 15-445 (Pavlo)](https://15445.courses.cs.cmu.edu/) · [DDIA](https://dataintensive.net/) · [Disk-First DB roadmap](https://learn.significanthobbies.com/learning/db-roadmap) ⭐ |
| **Networks** | OSI, HTTP/1/2/3, WebSocket, TCP/IP, checksums | [HPBN (Grigorik)](https://hpbn.co/) · [Beej's Guide](https://beej.us/guide/bgnet/) |
| **Distributed systems** | Two-generals, Byzantine failures, consensus (Raft, Paxos), distributed locks, leader election | [MIT 6.824](https://pdos.csail.mit.edu/6.824/) · [DDIA ch. 5/8/9](https://dataintensive.net/) · [Raft paper](https://raft.github.io/raft.pdf) · [Jepsen analyses](https://jepsen.io/analyses) |
| **Compilers** | Compilation lifecycle, JIT, key optimisations | [Crafting Interpreters (Nystrom)](https://craftinginterpreters.com/) · [Engineering a Compiler](https://www.elsevier.com/books/engineering-a-compiler/cooper/978-0-12-088478-0) |
| **OOP & LLD** | Design patterns, SOLID, dependency injection, "design X" problems | [System design (LLD section)](https://learn.significanthobbies.com/learning/system-design) ⭐ · [Refactoring.guru](https://refactoring.guru/design-patterns) |
| **Programming language** | Closures, futures, monads, type inference, GC, BEAM/JVM/V8 internals | [Runtime roadmap](https://learn.significanthobbies.com/learning/runtime-roadmap) ⭐ |
| **Microservice architecture** | Decomposition, SAGA, Strangler, sidecar | [microservices.io (Richardson)](https://microservices.io/) · [System design](https://learn.significanthobbies.com/learning/system-design) |
| **System design (HLD)** | Requirements, capacity, components, deploy, messaging, queues, infra | [System design (HLD section)](https://learn.significanthobbies.com/learning/system-design) ⭐ · [HelloInterview](https://www.hellointerview.com/learn/system-design) · [DDIA](https://dataintensive.net/) |
| **Caching** | In-memory vs distributed, Redis vs Memcached, write-through/back, eviction (LRU, MRU) | [Redis caching patterns](https://redis.io/docs/manual/client-side-caching/) · [Discord — Trillions of messages](https://discord.com/blog/how-discord-stores-trillions-of-messages) |
| **Load balancing** | L3/L4/L7, API gateway, SSL term, hot keys, DNS | [NGINX upstream](https://nginx.org/en/docs/http/load_balancing.html) · [Envoy listeners & filters](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/intro/arch_overview) |
| **Machine learning** | Supervised/unsupervised basics, neural nets, KFold, inference deployment | [fast.ai](https://course.fast.ai/) · [Karpathy Zero-to-Hero](https://karpathy.ai/zero-to-hero.html) · [ML case studies](https://learn.significanthobbies.com/learning/ml-case-studies) ⭐ |
| **Miscellaneous** | Latency numbers, MapReduce, serialization, mutex/semaphore, lock-free DS, OT | [Norvig/Dean latency numbers](https://gist.github.com/jboner/2841832) · [Art of Multiprocessor Programming](https://www.elsevier.com/books/the-art-of-multiprocessor-programming/herlihy/978-0-12-415950-1) · [Google SRE book](https://sre.google/books/) |

⭐ = the project's own deeper writeup.

## Behavioural / Leadership

Not in Atul Kumar's roadmap but every loop has at least one round of this.

- [STAR method](https://www.themuse.com/advice/star-interview-method) — the universal answer shape.
- [Manager READMEs catalog](https://managerreadme.com/) — read 5 to internalise what eng managers care about.
- [Lattice — Behavioural interview question bank](https://lattice.com/library/100-behavioral-interview-questions) — practice 10 against your last project.

---

# Reference books (one is enough)

- **[Cracking the Coding Interview (McDowell)](https://www.crackingthecodinginterview.com/)** — the DSA / behavioural classic.
- **[Designing Data-Intensive Applications (Kleppmann)](https://dataintensive.net/)** — the one HLD book.
- **[System Design Interview Vol 1 + 2 (Alex Xu)](https://www.amazon.com/System-Design-Interview-insiders-Second/dp/B08CMF2CQF)** — modern catalogue.
- **[Head First Design Patterns (Freeman & Robson)](https://www.oreilly.com/library/view/head-first-design/9781492077992/)** — the LLD classic.

## Companion docs in this project

- [System design — LLD + HLD](https://learn.significanthobbies.com/learning/system-design) ⭐ — the deep version of the LLD / HLD rows above.
- [Disk-First DB roadmap](https://learn.significanthobbies.com/learning/db-roadmap) — for the database rows.
- [Runtime roadmap](https://learn.significanthobbies.com/learning/runtime-roadmap) — for the programming-language row.
- [ML system design case studies](https://learn.significanthobbies.com/learning/ml-case-studies) — for the ML row.
- [SE Landscape](https://learn.significanthobbies.com/learning/swe-landscape) — broader survey of every domain in the table above.

## Maintenance notes

- NeetCode reorganises sporadically; `/roadmap` URL has been stable since 2023.
- CMU 15-445 URL is unversioned (302s to the latest year).
- MIT 6.S081 was renumbered to 6.1810; same materials.