hbarcelos / best-route

Finds the best (cheapest) route from a starting point towards a destination

Best Route

Summary

Given a file containing all available flight prices between different airports and the desired origin and destination, it gives you the best (cheapest) route.

Environment Setup

This project uses Node.js as runtime environment and Yarn as package manager.

Requirements:

• Node.js >= 11.0.0
• Yarn >= 1.13.0

After installing the packages above, clone this repository:

git clone https://github.com/hbarcelos/best-route.git

Switch to the project folder:

cd best-route

Dependencies

Once in the project folder, run to install the project dependencies:

yarn install

Usage

yarn start <ROUTES_FILE> "<FROM> - <TO>"

Testing

yarn test <TEST_FILE>

Architectural Overview

File structure

./
├── digraph/
│   ├── digraph.js
│   ├── digraph.test.js
│   ├── edge-set.js
│   ├── edge-set.test.js
│   ├── edge.js
│   ├── edge.test.js
│   ├── index.js
│   ├── priority-queue.js
│   └── priority-queue.test.js
├── csv.js
├── index.js
├── package.json
├── parse-available-routes.js
├── parse-query-route.js
├── read-file.js
├── sample-input.csv
├── test-runner.js
└── yarn.lock

Remarks

• Within the digraph folder lies the implementation of a Directed Graph, which provides a .shortestPath() method that is used to find the best route.
  • digraph.Digraph#shortestPath() implements a slightly modified version of the Dijkstra's Shortest Path First algorithm.
  • Instead of relying solely on arrays and maps, digraph.EdgeSet is a higher-level representation of graph edges.
  • digraph.PriorityQueue is used by digraph.Digraph#shortestPath() to allow prioritization of the cheapest nodes during graph traversal.
• parseAvailableRoutes is a pure functional pipeline to parse the routes CSV representation into a digraph.Digraph instance.
• parseQueryRoute will parse the second CLI param: the desired route.
• csv module is another pure functional pipeline to parse CSV text into JavaScript arrays.
  • It works only with in-memory CSV. The file read is performed in the main function in index.js before calling this function.
• readFile is a convenience wrapper around Node.js native fs module.