I was contacted via email by a tech recruiter. I was given a rather lengthy questionnaire to complete. The questionnaire requires a significant time and effort investment from the candidate. It included general soft skill questions related to tech, a scripting challenge, and a technical architecture question.

The recruiter didn't specify a time limit for the questionnaire, which was quite nice. They seemed to expect candidates to take their time and answer thoroughly. Unfortunately, the questionnaire proved to be a little too much effort, so I definitely cut a lot of corners while answering it. I feel like I was a bit arrogant and terse when answering most of the questions. Therefore, when they responded declining to move forward, I was not surprised.

Write a program, topN, that, given an arbitrarily large file and a number N, containing individual numbers on each line (e.g., a 200GB file), will output the largest N numbers, highest first. Tell me about the run time/space complexity of it, and whether you think there's room for improvement in your approach.