LOW-LEVEL DESIGN PRACTICE PATH
LLD machine coding problems
Use this path when an interview expects more than a class diagram. Each problem asks you to turn a behavioral contract into working Java, Python, or C++ code.
Begin with small state models, then add policies, recovery behavior, and larger workflows. The sequence is ordered to make each problem prepare you for the next one.
- Problems
- 10
- Languages
- Java · Python · C++
- Format
- Implementation
WHAT THIS PATH BUILDS
Practice the decisions behind working code.
- Translate requirements into cohesive objects and explicit invariants.
- Separate policy decisions from state transitions and storage.
- Handle invalid operations, retries, and partial workflows deliberately.
- Finish a runnable implementation inside a realistic interview timebox.
RECOMMENDED SEQUENCE
Build the skills in order.
Complete one section before moving to the next level of complexity.
01 Start with state and invariants
Build small, complete models before introducing multiple policies or asynchronous behavior.
02 Add policies and extension points
Practice behavior that varies by rule while keeping the main workflow readable.
03 Handle history and recovery
Make state transitions auditable and define what happens when an operation is reversed or repeated.
04 Finish with complete systems
Combine policies, state machines, failure handling, and operational constraints in one implementation.
COMMON FAILURE MODES
Review these before you submit.
- Starting with patterns before identifying the core operations and invariants.
- Building extension points for hypothetical requirements while the main flow remains incomplete.
- Leaving validation, duplicate operations, or state transitions implicit.
- Explaining a design without producing code that can be exercised end to end.