Hospital Simulator

Strictly compliant version with case-sensitive codes:

• Patients: F,H,D,T,X
• Drugs: As,An,I,P

Build & Run

Technical versions

• Java 17
• Spring Boot 3.5.x

Multiple parameters:

mvn clean package
java -jar target/hospital-simulator-1.0.0.jar "T,F,D" "An,I"
# => F:2,H:0,D:1,T:0,X:0

Single parameter (no drugs):

java -jar target/hospital-simulator-1.0.0.jar "D,D"
# => F:0,H:0,D:0,T:0,X:2

Input / Output

• Param 1: Inputs of patient states (D,F,F)
• Param 2 (optional): Inputs of drugs (As,I)
• Output (fixed order):

F:#,H:#,D:#,T:#,X:#

Rule Order (per patient)

1. Cures / Deaths
   • As or P cure F → H
   • An cures T → H
   • D dies (X) if I is absent
2. Side Effect
   • I + An ⇒ H → F
3. Fatal Mix
   • As + P ⇒ all living (F/H/D/T) → X
4. Resurrection
   • probability 1 / 1,000,000 : X → H (can be enabled/disabled)

X is unaffected by anything except resurrection.

Configuration

src/main/resources/application.properties

logging.level.com.evooq.hospital=INFO
simulator.resurrection.enabled=true

Tests & Coverage

mvn test jacoco:report
# report: target/site/jacoco/index.html

Tested

• Cures (As, P, An)
• D dies without I, survives with I
• I+An effect (including T cured → H then H → F)
• Fatal mix As+P
• Deterministic resurrection via RandomProvider stub (0% / 100%)
• Strict parsing (invalid tokens with WARN), empty inputs OK

Design & additional decisions

• Strict but tolerant parsing: unknown tokens are ignored (and logged as WARN) instead of throwing exceptions.
  Reason: remain robust for CLI, avoid a stray character blocking the entire simulation.
  Alternative (easy to enable): throw an exception on the first error — not chosen for KISS principle.
• Deterministic processing order: Phases are fixed (1→4): cures/deaths → side effects → fatal mix → resurrection. Guarantees consistent outcomes.
• Injectable RNG: RandomProvider enables reproducible tests (0% / 100%) and toggling resurrection via configuration.
• Data structures by intent:
  • Patients = List to preserve order and duplicates (realistic: multiple diabetics, etc.).
  • Drugs = LinkedHashSet/EnumSet for deduplication and O(1) membership checks; insertion order helps debugging.
  • Counting = EnumMap<HealthState,Integer> for compact, fast enum-keyed aggregation.
• Robust, strict parsing:
  • Unknown tokens are ignored and WARN-logged; empty/whitespace tokens are tolerated.
  • Trimming applied; null or empty inputs return empty collections (CLI remains resilient).
• CLI contract:
  • 0 args → usage is printed; >2 args → extra args ignored with WARN logging.
  • Output is always F,H,D,T,X in that order (script-friendly).
• Testability:
  • Unit tests cover cures, diabetes rule, side effects, fatal mix, resurrection (true/false), and edge cases.
  • End-to-end tests execute the CLI, capture stdout/stderr, and assert on the last non-empty line.
  • Parameterized tests reduce duplication for simple cure and diabetes scenarios.
• Challenge examples: examples #1, #2, #3 are covered, along with an end-to-end integration test (CLI).