Ayende (founder of NHibernate and RavenDB) shared a great interview task. Below is a copy of the original blog post:
Interview questions are always tough to design. On the one hand, you need to create something that is not trivial to do. On the other hand, you have a hard time limit for a reasonable solution.
For example:
- Implementing a linked list is something I would expect anyone to do in an interview.
- Implementing a binary tree (including balancing), however, is probably not feasible within an interview time frame.
Interview tasks that candidates can do at home are somewhat easier because there aren’t the same time constraints. However:
- If the task takes too long (e.g., a week to complete), candidates will skip the question — and the position entirely.
- If the task is too basic (e.g., “send a binary tree”), candidates will just:
- Google → Copy & Paste → Send.
- This teaches you nothing about their abilities.
Note: Sometimes you do learn a lot if a candidate cannot even manage the “copy & paste” solution. In such cases, they pretty much disqualify themselves. But we could assess that more easily with Fizz Buzz, after all.
So, I came up with the following question:
We have the following file (the full data set is 276 MB) that contains the entry/exit log for a parking lot.
The file format:
- The first value is the entry time.
- The second value is the exit time.
- The third value is the car ID.
- Encoding: UTF-8 text file
- Delimiter: Space-separated values
- Line Endings: Windows line endings
To generate a data file for testing, use the PowerShell script below.
This script generates a random data file that mimics the format described above. It creates lines with:
- Random ISO 8601 timestamps (entry and exit times).
- Random 8-digit car IDs.
- A customizable file size in megabytes (MB).
param(
[int]$FileSizeMB = 1, # Desired file size in MB
[string]$OutputPath = "data.txt" # Output file path
)Note: The repository includes Ayende original solutions along with my own attempts and final version. Enjoy!