Mars Rover

Guidelines

• Tech stack
  • Javascript or Typescript
  • Node and npm
  • Jest for running tests
• Do test-driven development
• Implement the functionality iteratively
  • It is recommended to write acceptance criteria for the requirements before starting
  • Use a tool (Google doc/Trello/Mural) to track your development tasks
• 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
• 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

Problem extensions

• Edge cases
  • Input validation - tell user is the input is invalid
  • Notify in output if rover goes past the edge and falls off the plateau
  • If rovers collide, the moving rover pushes the static rover one cell in the direction of movement
• 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
• 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
• Add obstacles on the plateau
  • Rocks that block the rover from moving
  • Mines that blow up the rover
  • Aliens that move back and forth
  • Sandstorms that throw the rover in a random location within a two-unit radius
• Add commands
  • Take samples of rocks and soil
  • Shoot projectiles to blow up obstacles
  • Take pictures of aliens
• Enhance the input/output
  • Animate the whole plateau with the moving rovers on the console
  • Send new inputs to the rover via the command line or a GUI
• Rovers and other entities all move at the same time
• Anything you think would be cool