Interview Prep

A comprehensive interview preparation toolkit covering coding patterns, system design, behavioral interviews, CS fundamentals, salary negotiation, resume/career prep, role-specific topics, AI-assisted interview scenarios, data analytics, low-level design, and production engineering. Track progress across 144 coding problems and 145 topics with a unified CLI dashboard. Solutions available in Python, C, C++, Rust, and JavaScript.

Features:

• WASM sandbox — user code runs safely inside wasmtime with fuel-based CPU limits, memory caps, wall-clock timeout, and no network/filesystem access
• Progress ring, stats cards, and per-section breakdowns
• Code Editor — auto-loads all in-progress problem files with CodeMirror syntax highlighting
• Save & Run — edit code in the browser, save (Ctrl+S), and run (Ctrl+R) directly from the editor header
• Terminal — PASS/FAIL/SKIP results panel
• Full-screen Code Page (/code) — dedicated coding layout with configurable terminal position (Right, Left, Bottom, Top), adjustable terminal width/height, and Ctrl+` to toggle terminal
• Language selector — toggle Python / C / C++ / Rust / JavaScript in Coding Patterns card or Settings sidebar, persisted to localStorage, filters file tree and Run output
• File tree sidebar — activity bar with collapsible file explorer
• Version history — every save creates a version snapshot; revert to any previous version
• Hint — toggle to view solution files directly in the editor
• Autocomplete — language-aware hints for Python, C, C++, Rust, and JavaScript
• Click any topic name to start it and open its files in the editor
• Filter by status (New / In Progress / Done) and instant search

Full-screen code editor (/code) with VS Code-style layout, configurable terminal, and Ctrl+` to toggle:

Progress dashboard with inline code editor:

See full dashboard screenshot

Quick Start

git clone https://github.com/quanhua92/interview-prep.git
cd interview-prep
docker compose up -d

Go to http://localhost:8888 to view the dashboard, or http://localhost:8888/code for the full-screen code editor.

Note: docker-compose.yml pulls a pre-built image from Docker Hub by default. To build locally instead, uncomment the build: . line and comment out the image: line.

For a minimal setup (no file persistence):

docker run -d -p 8888:8888 quanhua92/interview-prep

CLI

# Install dependencies
uv sync

# Install git hooks (blocks accidental commits of problem solve() methods)
git config core.hooksPath .githooks

# View progress dashboard
uv run python main.py status

# Run a problem file directly
uv run python tier1_foundation/sliding_window/problems/p003_longest_substring.py

# Mark topic progress
uv run python main.py update sliding_window in_progress
uv run python main.py update url_shortener completed

# Record a practice attempt
uv run python main.py attempt sliding_window

# Run problem stubs (default — expects SKIP for unimplemented problems)
uv run python run.py                   # WIP pattern problem stubs (Python)
uv run python run.py two_pointers      # Run a specific pattern's problems
uv run python run.py --all             # All pattern problem stubs

# Run solution files (answer keys)
uv run python run.py --solution         # WIP pattern solutions (Python)
uv run python run.py --solution --lang c   # All pattern solutions, C versions
uv run python run.py --solution --lang cpp  # All pattern solutions, C++ versions
uv run python run.py --solution --lang rs   # All pattern solutions, Rust versions
uv run python run.py --solution --lang js   # All pattern solutions, JavaScript versions

# Generate static HTML progress report
uv run python main.py report

# Launch interactive web dashboard (0.0.0.0:8888)
uv run python main.py start

WASM Sandbox

User code runs inside wasmtime (WebAssembly runtime) for safe sandboxed execution — fuel-based CPU limit, hard memory cap, wall-clock timeout, no network, no filesystem access unless explicitly mapped. Set WASM_SANDBOX=0 to force native execution (no sandbox).

Language	Toolchain	Compile	.wasm size
C	wasi-sdk (clang wasm32-wasip1)	~60ms	~100KB
C++	wasi-sdk (clang++ -fno-exceptions)	~340ms	~200KB
Rust	rustc wasm32-wasip1 + rstest rlib	~70ms	~1.9MB
JavaScript	QuickJS-NG WASI (single .wasm)	~100ms	~3KB
Python	CPython 3.14.5 WASI (pre-compiled .cwasm)	~60ms	27MB

Security: Fuel-based CPU limit, hard memory cap, wall-clock timeout, no network, no filesystem access unless explicitly mapped. See docs/WASM_SANDBOX.md for full details.

Project Structure

interview-prep/
├── main.py                        # CLI entry point
├── tracker.py                     # Data layer (CRUD on tracker.json)
├── web.py                         # FastAPI server + HTML dashboard
├── index.html                     # HTML template (Tailwind CSS)
├── static/app.js                  # Dashboard-specific JS (filters, status updates)
├── static/app.css                 # Shared editor and sidebar styles
├── static/editor-core.js          # Shared editor logic (CodeMirror, file tree, save/run/hint)
├── static/code.js                 # /code page logic (layout, terminal toggle)
├── static/code.html               # /code page (full-screen coding layout)
├── static/code.css                # /code page layout presets
├── static/codemirror/             # Vendored CodeMirror (syntax highlighting)
├── static/tailwind-browser.js    # Vendored Tailwind CSS runtime
├── Dockerfile                     # Docker image (Python 3.14-slim)
├── docker-compose.yml             # Docker Compose with volume mounts for progress + tier dirs
├── tier{1-4}_*/                   # 29 coding patterns
│   └── <pattern>/
│       ├── template.py
│       ├── problems/              # Practice stubs
│       ├── solutions/             # Answer keys
│       ├── test_runners/           # JudgeBase subclasses (test cases + I/O contract)
│       └── README.md
├── system_design/                 # 25 system design topics
│   └── <topic>/
│       ├── discussion.md
│       └── checklist.md
├── behavioral/                    # 12 behavioral themes
│   └── <theme>/
│       ├── discussion.md
│       └── checklist.md
├── salary_negotiation/            # 8 salary negotiation topics
│   └── <topic>/
│       ├── discussion.md
│       └── checklist.md
├── cs_fundamentals/               # 22 CS fundamentals topics
│   └── <topic>/
│       ├── discussion.md
│       └── checklist.md
├── resume_career/                 # 6 resume & career topics
│   └── <topic>/
│       ├── discussion.md
│       └── checklist.md
├── role_specific/                 # 6 role-specific topics
│   └── <topic>/
│       ├── discussion.md
│       └── checklist.md
├── ai_assisted/                   # 6 AI-assisted interview scenarios
│   └── <scenario>/
│       ├── README.md              # Interview prompt + follow-ups
│       └── TIPS.md                # Concepts, mistakes, AI strategy
├── data_analytics/                # 9 data analytics topics
│   └── <topic>/
│       ├── discussion.md
│       └── checklist.md
├── low_level_design/              # 12 low-level design topics
│   └── <topic>/
│       ├── discussion.md
│       └── checklist.md
├── production_engineering/        # 10 production engineering topics
│   └── <topic>/
│       ├── discussion.md
│       └── checklist.md
├── tests/                         # pytest suite
├── src/utils/                     # Shared utilities (Problem, TestCase, ListNode, TreeNode)
├── src/runners/                   # Cross-language test runners (C, C++, Rust, JavaScript)
├── src/wasm_libs/                 # Per-language IO libraries (linked into WASM or native)
└── progress/tracker.json          # Progress data (gitignored)

Coding Patterns (29 patterns, 4 tiers)

Tier 1: Foundation (Must Master)

Pattern	Key Problems
Sliding Window	P003 Longest Substring, P438 Find All Anagrams, P424 Longest Repeating Char, P567 Permutation in String, P395 Longest Substring K Repeating
Two Pointers	P167 Two Sum II, P011 Container With Most Water, P015 3Sum, P392 Is Subsequence, P524 Longest Word through Deleting, P532 K-diff Pairs
Fast & Slow Pointers	P141 Linked List Cycle, P202 Happy Number, P876 Middle of Linked List
Merge Intervals	P056 Merge Intervals, P253 Meeting Rooms II, P057 Insert Interval, P495 Teemo Attacking
BFS	P102 Binary Tree Level Order, P994 Rotting Oranges, P1091 Shortest Path Binary Matrix, P513 Find Bottom Left Tree Value, P515 Find Largest Value in Each Tree Row
HashMap / HashSet	P380 Insert Delete GetRandom, P398 Random Pick Index, P447 Number of Boomerangs, P500 Keyboard Row, P535 TinyURL, P575 Distribute Candies, P382 Linked List Random Node, P391 Perfect Rectangle
String Manipulation	P520 Detect Capital, P521 Longest Uncommon Subsequence I, P434 Number of Segments, P482 License Key Formatting

Tier 2: Intermediate (Very Common)

Pattern	Key Problems
DFS	P200 Number of Islands, P695 Max Area of Island, P1306 Jump Game III, P572 Subtree of Another Tree, P538 Convert BST to Greater Tree, P508 Most Frequent Subtree Sum, P450 Delete Node in a BST
Two Heaps	P295 Median Finder, P355 Design Twitter, P480 Sliding Window Median
Top K Elements	P215 Kth Largest Element, P347 Top K Frequent Elements, P973 K Closest Points, P407 Trapping Rain Water II
Binary Search	P704 Binary Search, P153 Find Minimum in Rotated Sorted Array, P278 First Bad Version, P354 Russian Doll Envelopes
Dynamic Programming	P070 Climbing Stairs, P322 Coin Change, P198 House Robber, P516 Longest Palindromic Subsequence, P518 Coin Change II, P514 Freedom Trail, P552 Student Attendance Record II, P576 Out of Boundary Paths
Prefix Sum	P560 Subarray Sum Equals K, P238 Product Except Self, P713 Subarray Product Less Than K, P523 Continuous Subarray Sum, P525 Contiguous Array
Stack	P020 Valid Parentheses, P394 Decode String, P155 Min Stack
Divide & Conquer	P023 Merge k Sorted Lists, P912 Sort an Array, P169 Majority Element, P427 Construct Quad Tree, P493 Reverse Pairs
Bit Manipulation	P191 Number of 1 Bits, P136 Single Number, P338 Counting Bits, P476 Number Complement
Randomized	P519 Random Flip Matrix, P470 Implement Rand10 Using Rand7
Math / Constructive	P458 Poor Pigs, P479 Largest Palindrome Product, P478 Generate Random Point in a Circle, P556 Next Greater Element III, P564 Find the Closest Palindrome
Design	P460 LFU Cache

Tier 3: Advanced (Important for Top Companies)

Pattern	Key Problems
Backtracking	P078 Subsets, P039 Combination Sum, P017 Letter Combinations, P473 Matchsticks to Square, P491 Non-decreasing Subsequences, P488 Zuma Game
Modified Binary Search	P033 Search in Rotated Sorted Array, P875 Koko Eating Bananas, P410 Split Array Sum
Cyclic Sort	P442 Find All Duplicates, P268 Missing Number, P448 Find Disappeared
Subsets	P046 Permutations, P090 Subsets II, P077 Combinations
Trie	P208 Implement Trie, P212 Word Search II, P211 Design Add and Search Words, P472 Concatenated Words

Tier 4: Expert (Differentiators)

Pattern	Key Problems
Union Find	P323 Connected Components, P684 Redundant Connection, P990 Satisfiability Equations
Monotonic Stack	P739 Daily Temperatures, P084 Largest Rectangle in Histogram, P853 Car Fleet, P907 Sum of Subarray Minimums, P456 132 Pattern, P503 Next Greater Element II
Greedy	P055 Jump Game, P455 Assign Cookies, P134 Gas Station, P135 Candy, P452 Min Arrows to Burst Balloons, P502 IPO, P621 Task Scheduler
Matrix Traversal	P054 Spiral Matrix, P048 Rotate Image, P498 Diagonal Traverse, P542 01 Matrix
Graph	P207 Course Schedule, P210 Course Schedule II, P997 Find the Town Judge

Each pattern contains:

• template.py — Annotated skeleton with variants
• problems/ — Practice stubs with test cases (implement solve())
• solutions/ — Answer keys (.py + .c / .cpp / .rs / .mjs counterparts)
• README.md — Pattern explanation, when to recognize it, complexity table

System Design (25 topics)

Topic	Core Concepts
URL Shortener	ID generation, caching, base62, sharding
Chat System	WebSockets, message queues, presence
Rate Limiter	Token bucket, sliding window, Redis
News Feed	Fan-out on write/read, graph, ranking
Notification Service	Push/pull, reliability, dedup, priority
Search Autocomplete	Trie, ranking, prefix search at scale
Distributed Cache	Consistent hashing, replication, eviction
Key-Value Store	SSTables, LSM trees, Bloom filters
Web Crawler	URL frontier, politeness, dedup, BFS
Ticket Booking	Concurrency, locks, idempotency, oversell
Abuse Detection	Velocity features, device fingerprinting, graph analysis, tiered mitigation
Ad Click Prediction	CTR prediction, multi-stage ranking, calibration, embedding tables
Coding Platform	Sandbox isolation, code execution, test cases, contest leaderboard
Customer LTV	Probabilistic CLV, survival analysis, uplift modeling, churn prediction
Demand Forecasting	Spatial-temporal ML, H3 zones, multi-quantile forecasting, online adaptation
Fraud Detection	Rules cascade, GBDT scoring, graph deep learning, sub-100ms latency
Gaming Leaderboard	Redis sorted sets, sharding, anti-cheat, tournament sliding windows
Hotel Booking	Date-range inventory, overbooking buffers, Redis holds, fan-out writes
News Aggregator	Vote-based ranking, nested comments, community feeds, hot algorithm
Online Auction	Bid serialization, proxy bidding, anti-sniping, WebSocket broadcast
Pastebin	Short URL, base62 ID, TTL expiration, CDN, object storage
RAG System	Hybrid retrieval, vector search, cross-encoder rerank, hallucination mitigation
Recommender System	Multi-stage pipeline, candidate retrieval, ranking, cold start
Search Ranking	BM25 + dense retrieval, learning-to-rank, cross-encoder, query understanding
Video Conferencing	SFU routing, WebRTC, simulcast, adaptive bitrate, TURN relay

Each topic contains:

• discussion.md — Concise reference (key concepts, trade-offs, vocabulary)
• checklist.md — Step-by-step working checklist with 5 phases + practice notes

Behavioral (12 themes, STAR method)

Theme	Competency
Amazon Leadership Principles	Leadership judgment, accountability
Meta Behavioral	Scope amplification, cross-functional influence
Teamwork Conflict	Collaboration, empathy
Handling Failure	Self-awareness, resilience
Leadership Without Authority	Influence, ownership
Difficult Decision	Judgment, trade-off analysis
Adapting to Change	Flexibility, prioritization
Working Under Pressure	Time management, composure
Receiving Feedback	Humility, growth
Mentoring a Teammate	Teaching, patience
Owning a Mistake	Accountability, transparency
Competing Priorities	Prioritization, stakeholder management

Each theme contains:

• discussion.md — STAR framework guidance, what interviewers look for, story mining prompts
• checklist.md — Story workshop with drafting checkboxes, refinement checks, practice log

Salary Negotiation (8 topics)

Topic	Focus
Market Research	Compensation data, leveling, market positioning
Total Comp Breakdown	Base, bonus, equity, benefits, hidden value
Initial Offer Evaluation	Reading offer letters, negotiation levers
Negotiation Tactics	Anchoring, framing, timing, communication
Equity & RSU Evaluation	Stock options, vesting, dilution, tax
Difficult Scenarios	Lowball offers, exploding offers, competing offers
Counteroffer & Staying	Counteroffer risks, resigning professionally
Remote Negotiation	Remote/hybrid comp adjustments, cost of living, location arbitrage

Each topic contains:

• discussion.md — Benchmarks, frameworks, scripts, talking points
• checklist.md — Preparation steps, script practice, scenario walkthroughs

CS Fundamentals (22 topics)

Topic	Focus
Operating Systems	Processes, threads, memory, file systems
Computer Networking	TCP/IP, HTTP, DNS, TLS, network models
Databases	SQL, indexing, transactions, ACID, normalization
Concurrency	Threads, locks, race conditions, deadlocks
Distributed Systems	CAP, consensus, replication, fault tolerance
Data Structures & Algos	Arrays, trees, graphs, hash tables, complexity
System Security	OWASP, auth, encryption, secure design
API Gateway	Routing, rate limiting, auth, TLS termination
Architectural Patterns	Recurring distributed system patterns
Auth Systems	JWTs, OAuth2, RBAC/ABAC/ReBAC
Back-of-Envelope	DAU, QPS, storage, capacity estimation
Bloom Filters	Probabilistic set membership, false positives
Caching Strategies	Cache write strategies, eviction, Redis
CDN	Edge caching, DNS routing, origin shielding
Consistency Models	Strong vs eventual, replication, quorum
Geohashing	Spatial indexing, proximity queries, coordinates
Idempotency Patterns	Safe retries, idempotency keys, fencing tokens
Load Balancer	L4/L7 routing, health checks, failover
Multi-Region	Replication, failover, conflict resolution
Realtime Protocols	WebSocket, SSE, long polling, WebTransport
System Design Framework	CIRCLE method, requirements, trade-offs
Zero-Downtime	Blue-green, canary, rolling, feature flags

Each topic contains:

• discussion.md — Key concepts, definitions, common questions, reference tables
• checklist.md — Concept self-assessment, explain-out-loud prompts, practice log

Resume & Career (6 topics)

Topic	Focus
Resume Structure	One-page format, sections, bullet writing
Elevator Pitch	30-60 second self-introduction
Career Narrative	Connecting experience into a coherent story
Explaining Gaps	Employment gaps, career changes, layoffs
Portfolio Showcase	Presenting projects, GitHub, writing samples
Questions for Interviewer	Strategic questions to ask at interviews

Each topic contains:

• discussion.md — Best practices, structure, good vs bad examples, common mistakes
• checklist.md — Drafting, refinement, and practice phases with practice log

Role-Specific (6 topics)

Topic	Focus
Backend Engineer	APIs, databases, services, scalability
Frontend Engineer	DOM, frameworks, performance, accessibility
Data Engineer	ETL, data pipelines, warehousing, streaming
ML/AI Engineer	ML fundamentals, deployment, evaluation
DevOps/SRE	CI/CD, containers, monitoring, reliability
Full-Stack Engineer	Frontend + backend breadth, system integration

Each topic contains:

• discussion.md — Core competencies, common topics, key terminology, cross-references
• checklist.md — Per-competency prep checklist, practice questions, system design bridge

AI-Assisted Interview Scenarios (6 scenarios)

Practice modern project-based interviews where you collaborate with an AI assistant to build, debug, or extend production-like systems — the format used by Meta, LinkedIn, and Google.

Scenario	Difficulty	Key Skills
URL Shortener	Medium	Encoding, caching, database trade-offs
Spreadsheet Application	Hard	Dependency graphs, cycle detection, concurrency
Distributed Rate Limiter	Hard	Throttling algorithms, distributed state, resilience
Maze Solver / Pathfinder	Medium	Graph traversal, pathfinding, memory optimization
Card Game Logic	Medium	Game rules, extensibility, input validation
Notification Service	Hard	Async processing, idempotency, priority queuing

Each scenario contains:

• README.md — Realistic interview prompt with requirements, starter code, and 4 progressive follow-up questions
• TIPS.md — Key concepts, common mistakes, AI prompting strategy, and what interviewers look for

See ai_assisted/README.md for the full guide including interview formats, evaluation rubric, and prompting strategy.

Data Analytics (9 topics)

Topic	Focus
Cohort & Retention	D1/D7/D30 retention curves and cohort SQL
Data Quality	Defense-in-depth monitoring and anomaly detection
Experiment Design	A/B testing from hypothesis to ramp
Funnel Analysis	Conversion drop-off diagnosis and attribution
North Star Metrics	Choosing and decomposing the one metric
Product Sense	Problem-first structured product reasoning
Scenario Problems	DIAGNOSE framework for metric triage
SQL Foundations	JOINs, NULLs, and CTE patterns
SQL Window Functions	Ranking, LAG/LEAD, and frame clauses

Each topic contains:

• discussion.md — Key concepts, definitions, common questions, reference tables
• checklist.md — Concept self-assessment, explain-out-loud prompts, practice log

Low-Level Design (12 topics)

Topic	Focus
Antipatterns	Spot and fix six design anti-patterns
API Design	Stable service contracts with idempotency and versioning
Behavioral Patterns	Object communication and delegation patterns
Database Schema Design	ER modeling, indexing, and online migrations
Design Framework	SEDIE 5-step repeatable LLD interview method
Design Patterns	Seven essential patterns for LLD interviews
LRU Cache	O(1) cache with concurrency and distributed scaling
Parking Lot	Multi-floor lot with spot matching and extensible pricing
Rate Limiter	Thread-safe, algorithm-swappable rate limiter
Refactoring Patterns	Incremental legacy modernization without big-bang rewrites
Shopping Cart	Immutable snapshots, idempotent checkout, aggregate boundaries
UML Class Diagrams	Correct relationship notation and Mermaid syntax

Each topic contains:

• discussion.md — Key concepts, definitions, common questions, reference tables
• checklist.md — Concept self-assessment, explain-out-loud prompts, practice log

Production Engineering (10 topics)

Topic	Focus
AI Coding Tools	Safe AI-assisted dev with generation, verification, learning loops
Capacity Planning	Forecast load with uncertainty and tiered headroom policies
CI/CD Pipelines	Safe fast delivery with test gates and deployment strategies
Cloud Cost	Systematic spend reduction through rightsizing and FinOps
Code Review	Structured review hierarchy from correctness to style
Feature Flags	Decouple deploy from release with typed flag taxonomy
Performance Profiling	Production profiling triage and flame graph reading
Postmortem	Blameless root cause analysis with actionable items
Security	Defense-in-depth across OWASP, secrets, and supply chain
SLO Error Budgets	Measurable reliability through error budgets and burn rate

Each topic contains:

• discussion.md — Key concepts, definitions, common questions, reference tables
• checklist.md — Concept self-assessment, explain-out-loud prompts, practice log