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0 / 120 Solved·0 / 125 Levels

Easy 0/57·Medium 0/77·Hard 0/111

Showing 20 of 20 systems

#	Challenge title	Domain	Difficulty
01	Build a Unix Shell PREQUELS 0/6 LEVELS 0/6	Command shell	Medium
PREQUELS (0 / 6)Focused coding problems · Solve in any order Start Prequels → Prequel 1Split a Line into Words· Strings, Tokenization Easy Prequel 2Find a Program's Path· Strings, Linear Search Easy Prequel 3Track Finished Tasks· Arrays, Strings Medium Prequel 4Split a Command into Stages· Arrays, Strings Medium Prequel 5Calculate Window Statistics· Sliding Window, Arrays Hard Prequel 6Top K Frequent Items· Arrays, Strings Hard LEVELS (0 / 6)Build a working system · One level at a time Start Level 1 → Level 1Builtin Command Execution (echo, pwd, cd, exit)· Strings, Parsing Easy Level 2PATH Resolution & Binary Execution (which, run, exec)· Strings, Linear Search Medium Level 3Process Lifecycle & Zombie Reaping (sigint, spawn-bg, reap)· Hash Maps, State Machines Medium Level 4Multi-Stage Pipelines & I/O Redirection (pipe, dup, >, >>)· Strings, Queues Hard Level 5Sliding-Window Latency Profiling (profile window)· Sliding Window, Arrays Medium Level 6Command History Frequency Ranking (hot k)· Hash Maps, Sorting Medium
02	Build an HTTP ServerLocked PREQUELS 0/6 LEVELS 0/6	Web server	Hard
03	Build a Git EngineLocked PREQUELS 0/6 LEVELS 0/6	Version control	Medium
04	Build a Key-Value StoreLocked PREQUELS 0/6 LEVELS 0/6	Key-value database	Hard
05	Build an Object StoreLocked PREQUELS 0/6 LEVELS 0/6	Object storage	Hard
06	Build an LRU CacheLocked PREQUELS 0/6 LEVELS 0/6	Memory cache	Medium
07	Build a Database IndexLocked PREQUELS 0/6 LEVELS 0/6	Database index	Hard
08	Build a Container RuntimeLocked PREQUELS 0/6 LEVELS 0/7	Container runtime	Hard
09	Build a Message QueueLocked PREQUELS 0/6 LEVELS 0/6	Message queue	Hard
10	Build a Log Analytics EngineLocked PREQUELS 0/6 LEVELS 0/6	Log processing	Medium
11	Build a Rate LimiterLocked PREQUELS 0/6 LEVELS 0/6	Rate limiting	Medium
12	Build a Load BalancerLocked PREQUELS 0/6 LEVELS 0/6	Load balancing	Hard
13	Build a Task SchedulerLocked PREQUELS 0/6 LEVELS 0/6	Task scheduling	Medium
14	Build a Raft Consensus ModelLocked PREQUELS 0/6 LEVELS 0/8	Distributed consensus	Hard
15	Build a Service RegistryLocked PREQUELS 0/6 LEVELS 0/7	Service discovery	Hard
16	Build a Distributed Object StoreLocked PREQUELS 0/6 LEVELS 0/6	Distributed storage	Hard
17	Build a Search EngineLocked PREQUELS 0/6 LEVELS 0/6	Search engine	Medium
18	Build a Vector DatabaseLocked PREQUELS 0/6 LEVELS 0/7	Vector database	Medium
19	Build an LLM Inference ModelLocked PREQUELS 0/6 LEVELS 0/6	AI inference	Medium
20	Build an MCP Tool RuntimeLocked PREQUELS 0/6 LEVELS 0/6	AI tool runtime	Medium

Showing 20 of 20 verified systems challenges

Python, C++, Rust, Go, Java Supported