Paytm Interview Experience for SWE | On-Campus 2021
Branch: Computer Science and Applied Mathematics (CSAM)
Duration of the process: 5 days (7th August 2021 – 11th August 2021)
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Pre-test Screening: A list of students eligible for the online coding round was shared. This was done on the basis of CGPA and Branch. Students with CGPA>=7.0 and all the branches except Computer Science and Biosciences(CSB) were shortlisted.
Online Coding Round – CoCubes (70 minutes)
- Check if a number is an Armstrong number.
- Find the number of elements in an array that are greater than all the elements on their right.
- Find the kth largest element in a BST using constant space.
I was able to pass all the test cases for all the questions and submitted the test in 22 minutes. A total of 54 out of 141 students (from B.Tech and M.Tech) were shortlisted for the interviews.
Round 1 – Google Meet (1 hour, 2 days after the Coding Round): The interviewer was very polite and good at communication.
- The round started with greetings and then the interviewer asked me about my hobbies.
- Then he asked me about one of the projects I had mentioned in my resume.
- He asked if I’m comfortable with Java. I replied I’m the most comfortable with C++. He asked how is memory managed in Java.
- Asked to explain the meaning of Object-Oriented Programming. Explain all of its 4 pillars with examples.
- Asked to explain ACID properties in DBMS.
- Then he asked if I can write MySQL queries. I replied yes, I can. So he asked me to write 2 MySQL queries. For an employee table:
- Find the person with the salary equal to the average salary of all the employees.
- Find the person with 2nd highest salary.
- Then he asked me 2 DSA questions:
- Reverse the first k nodes of a linked list. k can be greater than the length of the linked list.
- Maximum sum subarray with negative numbers and also print the subarray.
- In the end, he asked if I have any questions for him.
Make sure to communicate well with the interviewer while solving SQL queries and DSA questions. Also, make sure to ask the questions from the interviewer towards the end of the interview as it also shows that you are actually interested in the company.
Round 2 – Google Meet(40 minutes, 1 day after the 1st Round): The interviewer asked me to introduce myself. He also asked me about my hobbies.
- Then he asked about the recent technologies I had used. I had made a project in the machine learning course that I took in the previous semester. I described the technologies I used there.
- He asked me to rate myself in DSA out of 10. I gave myself a 6. Then he asked me my favourite data structure. I replied with “linked list”.
- He asked me to open a text editor and present my screen. Then he gave me the question to remove subarray of minimum size such that the sum of the remaining array is divisible by a given number k. I was asked to return the subarray to be removed. Also, the minimum possible size of the subarray that was to be removed should be 2. I was unable to fully solve this question, but I was told I am heading in the right direction.
- The interviewer then asked me my favourite technical subject apart from DSA. I replied with OOPs. Then he asked if I had done any non-technical courses in college.
He started with rapid-fire questions.
- What is the difference between Encapsulation and Abstraction? How are they implemented?
- What is Runtime Polymorphism?
- What is Dynamic dispatching?
- What is the OSI model? (As I had not done computer networks in college yet, I honestly told him that I had not done CN. He said it’s okay moved on to the next question.)
- What is multithreading?
- What is the SDLC model? (I wasn’t able to answer as I had not heard about it.)
- What is backtracking?
- What is one disadvantage of recursion?
- What is the Tower of Hanoi problem?
- What is the Travelling Salesman Problem? How would you approach this problem? I replied using recursion, and then we can use Dynamic Programming, as we will soon find out there will be overlapping subproblems.
- What are overlapping subproblems?
- How would you approach the problem of printing the second last node in a Linked list? Only the approach was expected.
- Lastly, he asked if I have any questions for him.
HR Round – Phone call (3 minutes, a few minutes after the end of the 2nd Round)
- I was congratulated as I had received positive feedback from the interviewers in the previous rounds.
- I was asked to introduce myself.
- I was asked about the interviews. How my experience was with the interviews.
- I was asked for the location preference.
A total of 23 students (from both B.Tech and M.Tech) were given the offer, and I was one of them.