Paytm Interview Experience for FTE+6 Months Internship (On-Campus)

First Round (Coding Round): Online Coding Test on COCUBES containing 3 coding questions and the duration was 70 minutes.

1. Operations in the binary string.  (No preference of Operators -3 marks)     

   A : AND 
   B : OR 
   C :  XOR       
   INPUT : 1C0B1A1
   OUTPUT :   1 

2. Contiguous subarray of unique elements max sum. (3 marks)
3. Palindromic Partitioning. (5 marks)

I have done all three but students getting 8 marks were also selected.

Out of 130, 26 got selected for the interview rounds. 

Second Round (Technical Interview 1): This round started with a detailed discussion of my projects. Some questions include 

• Why you have made this project and What are the real-time benefits of your project?
• Which technology have you used and why?

Tip: Be thorough with Technology and the detailed knowledge of your project.

Then the interviewer directly told me open the doc link and then asked some DSA questions

1. Reverse the singly linked list using recursion.
2. n-th node from the last in a singly linked list.
3. Reverse word in a given string.
4. Position of an element in a sorted array of infinite numbers.
5. An efficient way to multiply 2 to a number. (Simply left shift the number once)

This round lasted for an hour. I have answered all of them with a fully optimized approach. 

Tip: Always start from the brute force approach and then one by one give the optimized solution).

Out of 26, 16 were selected for the technical interview round 2.

Third Round (Technical Interview 2): Again the interview started with my projects. And after that he asked :

1. Difference between hash map and hash table.
2. Difference between the ordered map and unordered map.

Then, As I have written about a Chess Tournament in my resume that I had won. So he asked me :  

1. N queen problem.
2. Print n smallest elements from a given array in their original order. A slight change in the above problem, instead of a fixed array, I was asked for K minimum numbers in the stream of numbers that are coming continuously)

I had told 3 approaches for this problem, he was satisfied by my last optimized approach, this round took an hour. I have answered most of them correctly. In this round interviewer helped me a lot. 

Tip: The interviewer will give u some hints when u get stuck anywhere in the problem, So try to catch those hints, Those hints will lead you to the right solution)  

So out of 16, 12 got selected for 3rd technical interview round.

Fourth Round (Technical Interview 3): This round again started with my projects. Then  he asked : 

1. Microservices and distributed system
2. Difference between SQL and NoSQL
3. Data sharding

Then he switched to coding : 

1. Add two numbers represented by linked lists.

This round lasted for 45 minutes. Out of 12, 10 got the final offer. Luckily I was one of them.

Advice: Be calm and confident, It’s fine to say NO if you don’t know the answer. And those who are not in the CSE and IT branch, it doesn’t matter for the company like PayTM as I was from ECE.