SRE Code Test

First of all, thank you very much for your interest in the Site Reliability Engineer position at Cabify.

Get yourself comfortable and make sure to double check the test requirements.

You will have two weeks of time to complete the test. We would normally expect you to work on this no more than 2-3 hours, but you probably have other things to do in your life so we want to give you plenty of time in case you want to take on the challenge. If you don't, then it's perfectly fine. Just please let us know if this is the case.

If you have any questions about anything, please do not hesitate to ask us: better safe than sorry!

Looking forward to seeing the results. Good luck!

Problem

Write a simple command line interface (feel free to use any programming language you're comfortable with) that accepts two different arguments:

• A path to a file. This file is a plaintext file that contains a number per line.
• An integer number N (with a max value of 30000000)

With that in mind, your program will output the N largest numbers from the file, sorted from highest to lowest (numbers can be repeated).

Requirements

Your program will have to comply with the following requirements:

• Must build and execute in an Unix operating system
• Exit with custom errors when using wrong arguments, for example:
  • Filename does not exist: ERROR: input file does not exist.
  • Filename exists but it is not readable: ERROR: input file is not readable.
  • The integer N argument is less or equal to 0: ERROR: Number of top results must be bigger than 0.
  • The integer N argument is over the upper limit: ERROR: Maximum number of top results must be less or equal than 30000000.
• The program will ignore and warn about incorrect lines, for example:
  • Such as multiple numbers on the same line 12345 890
  • Or non numeric chars
    • Like 12345.01
    • Or 1234hello
  • Print warnings in the following format: WARN: Invalid line <line>
• The program will have to be as resource efficient as possible
• The program must be able to handle big files (1-2GB of size with tens of millions of lines).
• Avoid using third party libraries and stick with the standard ones

Tasks

• Provide the source code and instructions on how to build your program on this repository
• Answer the following questions (another text file on this repository will suffice):
  • What would be the time and space complexity of your program? Why?
  • Do you think there is still room for improvement in your solution? If so, please elaborate.