CodeNation Interview Experience | (On-Campus for SDE)

Round 1:

The first round was a coding round hosted on the HackerRank platform. There were 3 questions and we had 75 mins to solve all of them. I remember 2 of them.

One question was – given 2 strings str1 and str2, you have to find the length of the smallest circular substring in str1 containing all characters of str2. For example given strings ‘hackerrank’ and ‘kh’, the answer should be 2 (and not 4 because circular substrings are allowed). Expected time complexity O(n). This is a simple variation of this problem – https://www.geeksforgeeks.org/find-the-smallest-window-in-a-string-containing-all-characters-of-another-string/



Second question – given an unsorted array find the number of unordered triplets with product equal to a given number k. Expected time complexity O(nlogn). You can find the question here – https://www.geeksforgeeks.org/count-number-of-triplets-with-product-equal-to-given-number-set-2/.

You need to solve at least 2 questions to get shortlisted. Out of the 80 people who sat from my campus, 6 got shortlisted for further rounds.

Round 2:

This was a telephonic interview round lasting for about 30 mins. The interviewer went through my resume and told me to describe my most challenging work. He asked multiple questions related to my internship. The questions were really in depth and related to the domain of my work/project.



Tips – Be thorough with your resume. Describe a project/work experience that you are most confident in. Keep in mind that the questions related to your resume would not only be regarding the actual work, but would also test your domain knowledge.

Round 3:

This was a Skype interview round which lasted for about 1 hour. The interview tested my data structures and algorithms basics. He gave me 2 problems and made me write the code on collabedit.com.

The 1st question was to clone a linked list with next and random pointer – https://www.geeksforgeeks.org/a-linked-list-with-next-and-arbit-pointer/

2nd question was a variation of the box stacking problem – https://www.geeksforgeeks.org/box-stacking-problem-dp-22/. He made the problem a bit easier and asked me to work with envelopes instead of boxes. So in my case there were only 2 dimensions (length and breadth).

The interviewer was really friendly and made sure to provide not many, but sufficient hints whenever I got stuck. And also, the interviewer would most probably describe the problem incompletely, so before making any assumptions clear out everything with him/her.

Tips – Discuss all solutions with the interviewer before getting to the best one. Discuss your approach first and then code. You are expected to write totally bug-free code. Write comments where necessary.

Round 4:



This too was a Skype round lasting for about an hour. This was mainly an abstract brain-storming round. Firstly he told me to describe a time when I was stuck on something (and finally overcame it). This led to an in depth discussion of my internship and the work I did there. He didn’t ask any questions but allowed me to describe my work in detail. And since most of my projects were based on Machine Learning/Deep Learning, he asked me ‘what would I do if I am a data scientist working for Facebook with access to all of Facebook’s data?’ (yeah he said the exact same line). This followed with around 40 mins of discussion, I came up with many ideas and possibilities in which the data could be useful, from the perspective of both a user and Facebook itself. He was not interested in the actual implementation of any idea, but wanted to see how was I thinking and improving on my own idea.

Tips – For open-ended questions like these, always state the assumptions and the reasoning behind your ideas. Find pros/cons in your ideas before the interviewer does.

Round 5:

This was an HR round with the CEO which went on for about 25 mins. For me this was the most fun round. Firstly he asked normal questions like, describe a tough situation you have faced, describe your most interesting project etc. When he got to know I play the guitar, he asked me a design question – how would you detect the raga in a song, which led to a less-technical and more music based discussion. In the end he asked why I wanted to join CodeNation. This interview ended with me asking him 2 questions about CodeNation.

The following 2 Tips matter the most –

  1. Believe in yourself.
  2. Keep calm and get placed.

Got the offer. 🙂

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