Walmart Interview Experience for SDE-3 Data Engineer 2022

I applied via referral from LinkedIn.  I got a call from the HR team for scheduling an interview.

Round 1 (Online Coding round): (Online coding round was skipped as I was referred by the manager, for his team). 

Round 2 (DS Algorithm: 1 hr): This round started with a brief introduction, followed by 2 coding questions.

• Next Greater Element
  https://www.geeksforgeeks.org/next-greater-element/
  First I explained him my understanding about the question and then implemented brute force code for the problem and then he asked about the complexity of the solution and also to optimize the solution. I was able to do that.
•  Sort a nearly sorted (or K sorted) array
  https://www.geeksforgeeks.org/nearly-sorted-algorithm/
  Same process as the first question. Different is just that here I got confused with the complexity of optimised code. Later I was able to explain that as well.

We finished the above 2 questions in 45 min, however interview was for 1 hour, so the interviewer asked about algorithms and their complexity and there use cases related to sorting like insertion sort, merge sort, quick sort, etc.

Round 3 (HLD + LLD: 1 hr): The interviewer was very polite and very formal.

• Started with a brief introduction, during this I told him that I have very less or no knowledge of Data engineering.
• Interview started with basic core java questions like override and overloading methods.
• After that he asked me to create a Model class (called Bike) with few properties on which he wanted to apply comparator and comparable and few other manipulations on code like creating the HashSet of Bike Object and checking equality of 2 Object. Also asked about the Facade design pattern and asked me to implement it for Bike class with a use case (Don’t exactly remember now). Also asked about many other design patterns and their use case.
• Then he started asking questions related to multi threading and it’s implementation like Runnable, Thread class, and all the thread and object class methods and their uses. 
• Then he jumped to Executor services, asked about types of executors, and asked to implement each of them with Bike class. 
• Then we discussed Future and callable, followed by its implementation.

  Both rounds 1 and 2 happened on the same day(Friday). It was a bit late in the evening so they decided to move the HM round to the next working day(Monday).

Round 4 (Hiring Manager: 1 hr): 

• Started with a brief introduction about the personal and professional background.
• This was majorly tech round and the majority of the questions were related to data streaming only, which I have less knowledge, so I tried explaining everything by the use of Java streams. Explained with many examples and use cases of different methods. Used zoom whiteboard to draw the data pipeline and explain the solution.
• She was majorly interested in Data Quality Checks like How will you take care that data is not duplicated, there is no data loss, handling high volumes of data, speed of data transfer, data manipulation, etc.
• Asked about working with Kafka and its basics – I had a brief idea about that.
• SOLID Principles – At that time I didn’t remember the full form of each principle but I knew the crux of this, so explained that and she was satisfied.
• Asked about how agile is followed in your previous company. 
• Behavioural Questions : 
    Good/Bad thing about you.
    Anything that you have accomplished in your last company and you were recognised(awards/hackathon) for that.
• Overall this round was average.

Round 5 (HR round: 1 hr):  

• Started with a basic introduction. 
• Asked about a few positives and negatives about me.
• Discussed my current salary structure.
• Asked about my expected salary and why do you want to switch from your previous company. What are your expectations from Walmart?  
• Explained about Walmart’s salary structure like CTC is divided into multiple parts i.e Basic pay, PF, MIP (Bonus), and RSUs.
• Explained a bit about Walmart. Also about other benefits that Walmart provides.
• Overall response was positive. It was more of a behavioral round, checking if a person is fit for the company and salary expectations. 

Verdict : 

Overall interviews were very good. After 2 weeks finally got a very good offer.