Mars Rover

Guidelines

Tech stack
- Javascript or Typescript
- Node and npm
- Jest for running tests
Do test-driven development
Implement the functionality iteratively
- Break down the requirements, you can use acceptance criteria if you like
- Use a document or tool like Trello to track your work
There are many solutions for this problem online but DON’T LOOK AT THEM!

Setup

Fork your own copy of this codebase and clone it
- Alternatively, you can set up your own project from scratch if you want to practice doing that
Install nvm
- nvm lets you switch Node versions between projects
- This project has an .nvmrc file with a specific version of Node
- Run nvm install to install Node
- Run nvm use to switch Node versions
- Optional but recommended: set up shell integration to automatically switch versions based on directory
  - I use the custom hook in .zshrc
Install dependencies: npm install
Run tests: npm run test or npm run test:watch
Run the app: npm start

Problem description

A squad of robotic rovers are to be landed by NASA on a plateau on Mars. This plateau, which is curiously rectangular, must be navigated by the rovers so that their on-board cameras can get a complete view of the surrounding terrain to send back to Earth.

A rover’s position and location is represented by a combination of x and y coordinates and a letter representing one of the four cardinal compass points. The plateau is divided up into a grid to simplify navigation. An example position might be 0, 0, N, which means the rover is in the bottom left corner and facing North.

In order to control a rover, NASA sends a simple string of letters. The possible letters are ‘L’, ‘R’ and ‘M’. ‘L’ and ‘R’ make the rover spin 90 degrees left or right respectively, without moving from its current spot. ‘M’ means move forward one grid point in whatever direction the rover is facing, and maintain the same heading. Assume that the square directly North from (x, y) is (x, y+1), whereas the square directly East from (x, y) is (x+1, y).

Input:

The first line of input is the upper-right coordinates of the plateau, the lower-left coordinates are assumed to be 0,0.
The rest of the input is information pertaining to the rovers that have been deployed. Each rover has two lines of input. The first line gives the rover’s position, and the second line is a series of instructions telling the rover how to explore the plateau.
The position is made up of two integers and a letter separated by spaces, corresponding to the x and y coordinates and the rover’s orientation.
Each rover will be finished sequentially, which means that the second rover won’t start to move until the first one has finished moving.

Output:

The output for each rover should be its final coordinates and heading.

Example

Input:
5 5
1 2 N
LMLMLMLMM
3 3 E
MMRMMRMRRM

Expected Output:
1 3 N
5 1 E

Modules

Module 1 - Happy path

Read input
Move rovers according to instructions
Print output

Module 2 - Edge cases

Input validation
- Notify user of error if the input is invalid
  - Missing file
  - Invalid format e.g. bad characters
  - Rover is initialized outside plateau
Rover goes over edge and falls off plateau
- Stop moving the rover after it falls
- In output, include final position plus an indicator that they fell: 1 6 N (fell)

Module 3 - Expand rover movement

Move the rover backwards when the instruction is B
Allow turns to be 90 or 45 degrees with diagonal movement
- Lowercase l and r for 45 degrees
- Uppercase L and R for 90 degrees

Module 4 - Enhance the simulation

Instead of executing all the instructions for a rover at once, execute one instruction for each rover in turn
- Example:
  - First instruction for rover 1
  - First instruction for rover 2
  - First instruction for rover 3
  - Second instruction for rover 1
  - Second instruction for rover 2
    - Etc
Print the whole plateau with the rovers as output. For instance, the expected output from the original example would be:

. . . . . .
. ↑ . . . .
. . . . . .
. . . . . →
. . . . . .

Extra credit: animate the movement of the rovers on the console one frame at a time
- All the rovers should update together per frame
- This library will help

Module 5 - Plateau obstacles

Add rocks which block the rover from moving
Sandstorms that throw the rover in a random location within a three-unit radius (including off the plateau)
If rovers collide:
- The moving rover pushes the static rover one cell in the direction of movement

Module 6 - More plateau fun

New entities
- Mines that blow up rovers when they are run over
- Aliens that move in or out of the ground like prairie dogs every turn
New rover commands
- Drill rocks to destroy them
  - Rover must be facing and adjacent to rock
- Take pictures of aliens
  - Rover must be facing the alien, max 3 units away, with no obstacles in between, alien out of the ground

Module 7 - UI and Animation

Run the app in the browser
Add a form in the UI for specifying the inputs and running the program
- Plateau size, rovers, instructions, obstacles, etc
Use the Canvas API to animate the action each turn

GOECHA/mars-rover