All problems below require some kind of input. You are free to implement any mechanism for feeding input into your solution (for example, using hard coded data within a unit test). You should provide sufficient evidence that your solution is complete by, as a minimum, indicating that it works correctly against the supplied test data.
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 co-ordinates 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' makes the rover spin 90 degrees left or right respectively, without moving from its current spot. 'M' means move forward one grid point, and maintain the same heading.
Assume that the square directly North from (x, y) is (x, y+1).
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 co-ordinates 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.
The output for each rover should be its final co-ordinates and heading.
Input and output files
Test Input:
5 5
1 2 N
LMLMLMLMM
3 3 E
MMRMMRMRRM
Expected Output:
1 3 N
5 1 E
This is a simple solution for the Mars Rovers Challenge, and I chose Node because it's backend and because it's Javascript and I have been using it a lot lately.
These instructions will get you a copy of the project up and running on your local machine for testing purposes.
This solutions was written and tested on a Linux machine, and I also tested on a Mac but I never testes on Windows because I simply don't have a Windows computer.
You need to have Node installed to run this project.
$ cd ~
$ curl -sL https://deb.nodesource.com/setup_6.x -o nodesource_setup.sh
$ sudo apt-get install nodejs
Check installation
$ node -v
Output
v6.0.0
First, download the project, then cd into the project and install dependencies.
$ git clone https://github.com/rcabarreto/marsrovers.git marsrovers/
$ cd marsrovers/
$ npm install
On the root of the project, you'll find a file called input.json. This file stores all the information needed to run the application and this information is loaded from the file every time you run the program.
On the file you can configure the dimensions of the plateau (up to 8 by 8) and as many as 12 rovers.
{
"plateau": {
"width": 5,
"height": 5
},
"rovers": [
{ "start": { "x": 1, "y": 2, "o": "N" }, "path": "LMLMLMLMM" },
{ "start": { "x": 3, "y": 3, "o": "E" }, "path": "MMRMMRMRRM" }
]
}
To run a test in text mode, you can use the command:
$ ./runRover.js
To see the rovers moving on the plateau, first make sure you are running your terminal full screen or else it'll break, then use the command:
$ ./runRover.js -g
There's a cool test I wrote for 12 Rovers on a 8x8 plateau, to see it just run:
$ ./runRover.js -gi swarm.json
There are some more options, to list them just run:
$ ./runRover.js -h