I had five rounds of interview @Hackerrank. I was rejected because of my weak data structure knowledge (I don't think I was that bad). I don't know why they dragged me to the last CEO round.

After the CEO round, HR said, "We have a doubt regarding your data structure knowledge; you will have one last round with the CTO again."

I was asked to design an algorithm that would help a user identify a safe position to place a marble. The condition was that there should be a marble in the up, down, left, and right directions, irrespective of row and column.

I completed this question as well, but later I was rejected, saying that the CTO was disappointed by the approach I used, although my algorithm worked for the entire problem statement. I was quite disappointed after this.

1. How will you design a parking system?

2. Connect all 1s to make an island in an NxN matrix.

3. Design a project for a candidate/recruiter management system in which one candidate will be assigned to only one recruiter, but one recruiter can have multiple candidates. I was asked to create this using the Sinatra framework and Backbone.js.

4. CEO Round: Why would you like to work at HackerRank? Why do you want to leave your current organization?