Zenon Interview Experience for SDE (On-Campus) 2022

Round 1: Objective Exam based on Aptitude,  DBMS,  Operating System,  SQL Queries

• This round was conducted offline in the lecture hall of my college.
• A total of 140 students took this test.
• The exam Sheet contains 3 sections: Mathematics/Aptitude, DBMS/Operating System, and SQL queries.
• You must have a good hold over computer science core subjects.
• And, yes there was negative marking for each wrong attempt, as well, i.e., -25%.
• A total of 20 students were shortlisted after round 1. 

Round 2: Technical Interview 1: Here, the whole discussion was around Java architecture, SQL queries, and one question related to optimization. Questions were: 

• Introduce yourself
• What is bytecode in Java? Use of it?
• What is JVM?
• Can we install multiple JVMs on one system? If yes, then what will be the benefit then?
• What are Iterators in Java?
• Suppose you are given a file containing words, you have to read the words of the file and do the following operations:
• If the word length is less than 5 then directly store it in another file as it is.
• If a word is greater than 5 and then remove all vowels from it and store it in another file.
• How would you optimize the above operations in terms of space and time?

At last, the interviewer asked a SQL query:

• Display the name of the department, and the count of students in each department from the table department and student.
• Around 10 students were shortlisted after this round.

Round 3: Technical Interview 2 (System Design): In this round, the interviewer first asked me for an introduction and then asked the following questions:

• You have to design a food delivery service (you can take the example of zomato), considering all the required entities involved, their relationships and operations associated with it, etc. How would you design? What do you think?
• The second question was, Consider at the client side, there is a form with a submit button. And after clicking the button, a request has been sent to the server for processing. Now the problem is, on the client side, the client may click the same button multiple times and each time the same request is sent to the server. How would you prevent duplicate requests on the server side?
• The third question was related to database table design and querying.
• You are given a relation that the student is associated with the department and each student can take n number of courses.
• How many tables do you need to organize data?
• Then he asked me to write a query related to the above configuration (not remember the exact query)

Round 4: Technical Interview 3 (UI Design, OOPs, DSA): This round again started with my introduction. And in my resume, there was written react js. So he gave me a problem related to UI design. 

• In UI design, I have to organize and maintain transitions in pages using react js. The first page was the login page, the second was the home page with 2 links, and links associated with one page each. (I explained, I will retain login credentials using local storage after login, then using router I will redirect to the respective page after clicking links, and will also use hooks to maintain props)
• In the second question from DSA, you are given a number ranging from 1-1000, and you have to return a string that contains the English format of that number. (e.g., 145: One Hundred Forty-Five).

One question from the data structure:
You are given a network of friends(imagine Facebook), see the below illustrations:

Friend A	Friend B	The time when they connected
F1	F2	T1
F3	F4	T2
F5	F6	T3
F2	F3	T4

             Now you have given queries based on the above connections. For example, tell the time when F2 connected to F4.(Answer: T4). You have to tell which data structure you will use and what will be your approach to solve this problem.

• Difference between Method Overloading and Method Overriding.
• What is Inheritance?
• Output prediction (Multilevel Inheritance)
• Again, at last, he asked to write a SQL query by giving a database scenario. Find the topper student name and his department name from each department from the university database.
• Database Tables:
  • Student (id, name, dept_id, score)
  • Department (id, name)

After this round, only 3 students left.

Round 5: HR Interview:

• Tell me about yourself
• From which city do you belong?
• What are your tech interests?
• Followed by OOPs concepts
• Difference between Aggregation and Composition
• What is Joins and types of joins
• Cartesian product and real-world example?

Total 2 students were selected after this round including me.

Verdict: Selected!