Technical Challenge - Interstellar Route Planner

Brief

Hyperspace Tunneling Corp manages a system-to-system web of hyperspace accelerators that spans the United Terran Systems. They charge a fee to their users in order to use their network but they want to expand their business.

Recently, they've expanded into transporting people through their network using light transport space-ships that can take up to 5 people to the accelerator and then use their hyperspace-enabled ships to travel to the destination accelerator.

We've been asked to develop a system to help calculate the costs of this journey for their clients.

A journey is defined as:

1. Journey to the accelerator:

   • Personal Transport: £0.30/AU (standard fuel cost) plus £5 per day for ship storage at the accelerator - (fits up to 4 people)
   • HTC Transport: £0.45/AU - (fits up to 5 people)

2. An outbound and an inbound hyperspace journey:

   • Spaceflight: £0.10/passenger/hyperplane-unit

HTC keeps a table with its accelerators and their connections:

Accelerator ID	Accelerator Name	Connections and Hyperplane units of distance (HU)
SOL	Sol	RAN: 100HU PRX: 90HU SIR: 100HU ARC: 200HU ALD: 250HU
PRX	Proxima	SOL: 90HU SIR: 100HU ALT: 150HU
SIR	Sirius	SOL: 80HU PRX: 10HU CAS: 200HU
CAS	Castor	SIR: 200HU PRO: 120HU
PRO	Procyon	CAS: 80HU
DEN	Denebula	PRO: 5HU ARC: 2HU FOM: 8HU RAN: 100HU ALD: 3HU
RAN	Ran	SOL: 100HU
ARC	Arcturus	SOL: 500HU DEN: 120HU
FOM	Fomalhaut	PRX: 10HU DEN: 20HU ALS: 9HU
ALT	Altair	FOM: 140HU VEG: 220HU
VEG	Vega	ARC: 220HU ALD: 580HU
ALD	Aldermain	SOL: 200HU ALS: 160HU VEG: 320HU
ALS	Alshain	ALT: 1HU ALD: 1HU

graph TD
    SOL[Sol]
    PRX[Proxima]
    SIR[Sirius]
    CAS[Castor]
    PRO[Procyon]
    DEN[Denebula]
    RAN[Ran]
    ARC[Arcturus]
    FOM[Fomalhaut]
    ALT[Altair]
    VEG[Vega]
    ALD[Aldermain]
    ALS[Alshain]

    SOL --100--> RAN
    SOL --90--> PRX
    SOL --100--> SIR
    SOL --200--> ARC
    SOL --250--> ALD
    PRX --90--> SOL
    PRX --100--> SIR
    PRX --150--> ALT
    SIR --80--> SOL
    SIR --10--> PRX
    SIR --200--> CAS
    CAS --200--> SIR
    CAS --80--> PRO
    PRO --80--> CAS
    DEN --5--> PRO
    DEN --2--> ARC
    DEN --8--> FOM
    DEN --100--> RAN
    DEN --3--> ALD
    RAN --100--> SOL
    ARC --500--> SOL
    ARC --120--> DEN
    FOM --10--> PRX
    FOM --20--> DEN
    FOM --9--> ALS
    ALT --140--> FOM
    ALT --220--> VEG
    VEG --220--> ARC
    VEG --580--> ALD
    ALD --200--> SOL
    ALD --160--> ALS
    ALD --320--> VEG
    ALS --1--> ALT
    ALS --1--> ALD

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Accelerators are typically one-way, so while the route A->B can exist, it doesn't necessarily mean that B->A exists. Additionally, the hyperplane distance varies depending on which way you travel - Our best theories say the hyperplane not only does not match real-space but also has a preferred direction.

Accelerator Data

Feel free to use any form of storage for the accelerator and routes information.

You can make use of create-local-db.sh which sets up a local DynamoDB with the data in the table above.

Your task:

Write a program that suggests the cheapest quote for a customer's journeys.

This program should expose its logic via an API so that it can be consumed by other services or a browser client.

The API should expose, at least, the following endpoints:

• GET: /transport/{distance}?passengers={number}&parking={days} - returns the cheapest vehicle to use (and the cost of the journey) for the given distance (in AUs), number or passengers and days of parking (i.e. vehicle storage at the accelerator)
  • Accelerators typically sit above the star, so if you're on Earth and want to travel to the Sol accelerator, the distance would be ~1AU.
• GET: /accelerators - returns a list of accelerators with their information
• GET: /accelerators/{acceleratorID} - returns the details of a single accelerator
• GET: /accelerators/{acceleratorID}/to/{targetAcceleratorID} - returns the cheapest route from acceleratorID to targetAcceleratorID

These endpoints should be public.

Expectations

• A git repository with the solution
  • Application code
    • Use any programming language you like (unless stated otherwise)
  • API documentation - e.g. Swagger, Postman collection
  • Any tests
  • Any CI/CD configuration - e.g. github actions
  • Any infrastructure-like config - e.g. Dockerfile(s)
  • Any supporting scripts to generate, package, run, etc...
• A dockerhub image with the solution and instructions on how to run it (and/or a docker-compose file)
  • Optionally, feel free to host this for us somewhere as well.

Getting help

If you have any questions, please feel free to reach out to me via email (tco@keyholding.com).

This is a genuine offer for help - I want to see you succeed! - and it lets me understand how you work and communicate.