Paytm (One97 Communications Limited) interview experience Real time questions & tips from candidates to crack your interview
Software Engineer
Paytm (One97 Communications Limited)
4 rounds | 6 Coding
problems
Selected Interview preparation journey
Preparation
Duration: 6 Months
Topics: OOPs Concepts, DS & Algo (Array, LinkedList, Tree, String, Stack, Queue, Dynamic Programming), High Level System Design (Different AWS services like EC2, API Gateway, Load Balancer, Auto Scaling Group, RDS, S3 bucket )Low Level System Design, Database concepts ( ACID properties, CAP theorem, SQL queries )
Tip 1 : Practice at least 10-20 questions of DS & Also on each topic from difficulty level easy to hard.
Tip 2 : Prepare well around OOPs concepts and Database concepts.
Tip 3 : If you have 2.5+ year of experience practice around HLD and LLD.
Application process
Where: Other
Eligibility: No Criteria
Tip 1 : Please mention the keyword related to the work that you have done. (eg. Git, Maven, JUnit, Java, AWS )
Tip 2 : Please mention any certification that you have done. And try to keep your resume within one page.
Interview rounds
01
Round
Medium
Video Call
Duration60 minutes
Interview date26 Jun 2021
Coding problem2
Paytm HR called for the interview availability. All three rounds were scheduled on the same day. This round was set up around 11am to 12pm.
Interview environment was positive. Interviewer made me comfortable by asking normal question about me and the work that I have done.Overall the interview experience was really great. I was able to provide optimised solution for both DS Algo problem.
1. Valid Parentheses
Easy
10m average time
80% success
0/40
Asked in companies
You're given a string 'S' consisting of "{", "}", "(", ")", "[" and "]" .
Return true if the given string 'S' is balanced, else return false.
For example:
'S' = "{}()".
There is always an opening brace before a closing brace i.e. '{' before '}', '(' before ').
So the 'S' is Balanced.
Problem approach
Step 1 : I gave the solution using stack and since I wanted to use the property Last In First Out.
Step 2 : Whenever we get open bracket we push the item in stack and when we get the closing bracket, match it with stack top opening bracket. Keep doing until you process all the element. Anytime if the stack top doesn't match with current closing bracket then It is not valid case.
2. Right View
Moderate
35m average time
65% success
0/80
Asked in companies
You have been given a Binary Tree of integers.
Your task is to print the Right view of it.
The right view of a Binary Tree is a set of nodes visible when the tree is viewed from the Right side and the nodes are printed from top to bottom order.
Problem approach
Step 1 : Level order traversal using queue.
Step 2 : print the last node at each level.
02
Round
Medium
Video Call
Duration60 minutes
Interview date26 Jun 2021
Coding problem2
All rounds were scheduled on the same day in day time.
Interview environment was positive. Interviewer made me comfortable by asking normal question about me and the work that I have done.Overall the interview experience was really great.
1. Java Questions
Can constructor be made final in java
Can Objects be created from abstract class.
Can abstract class have constructors Comparable vs Comparator
Questions on Java(Executor Service)
Problem approach
Since I have gone through the concept of OOPs concepts. I was able to answer the java related question.
2. Kth largest element
Moderate
0/80
Asked in companies
Ninja loves playing with numbers. One day Alice gives him some numbers and asks him to find the Kth largest value among them.
Problem approach
step 1: I gave the solution using the min heap of K size.
step 2 : add element to heap if heap size is less than k
step 3 : if heap size is k then remove the min element when current element is greater than the min heap element and push the current element.
step 4 : Do this for all the element in array.
step 5 : return the heap min element.
03
Round
Medium
Video Call
Duration60 Minutes
Interview date26 Jun 2021
Coding problem1
All three rounds were scheduled on the same day in day time.
Interview environment was positive. Interviewer made me comfortable by asking normal question about me and the work that I have done.Overall the interview experience was really great.
1. System Design Questions
Round 3: Java and HLD
Create custom compile time and runtime exception
Capturing order of exceptions in catch clause
Cowin - HLD design
Cowin - HLD Design
Different Tables to be used
Registering a User
Functionality to search based on Area Pincode, vaccine type
Handling Single User registering for multiple people
Type of Database to be used, and Database sharding strategies
Handling concurrency and parellelism when multiple users book for a time slot having limited number of vaccines. Eg) within 2 - 2:30 pm slot having 20 available vaccines how to handle multiple users booking that slot
After a slot is booked, how to verify if that particular person registered for that slot has been vaccinated or not for that particular slot
Problem approach
Tip 1 : Clarify the problem with the interviewer and define the scope of the problem.
Tip 2 : List down the requirements that interviewer is asking to implement.
Tip 3 : Practice basics of System Design concepts like - Load balancing, Auto scaling, API Gateway, Cache, Horizontal and vertical scaling.
04
Round
Easy
HR Round
Duration15 minutes
Interview date28 Jun 2021
Coding problem1
Since all the rounds feedback was positive. HR called me to discuss about my expectation.
1. Basic HR Questions
What are your expectations?
Who is your role model?
Here's your problem of the day 
Solving this problem will increase your chance to get selected in this company
Skill covered: Programming
To make an AI less repetitive in a long paragraph, you should increase:
Choose another skill to practice
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