Paytm Interview Experience for Software Engineer (6 Months Internship + FTE)

Round 1 (Online Coding): The first round was held at Cocubes platform and 3 coding questions were given to us to solve in a duration of 70mins.

1. A Boolean Matrix Question (3 marks)
2. Print sum of given series (3 marks)
3. Two trees were given and first, we have to find either tree is a subtree of another tree then we have to print the count of nodes in that subtree. (5 marks)

I have done all 3 but students getting 8 marks were also selected.

Around 60 students were selected for the next round.

Round 2 (Technical Round 1): This round was conducted by a Senior Software Engineer for 45 minutes. The interviewer was super friendly and cool. The interviewer told me to open the codepad and asked some DSA questions.

1. He asked me to sort an array then we discuss some sorting algorithms and their best and worst case.
2. He gives me a linked list sorted according to the absolute value of the nodes. Then he asked me to sort this link list based on their actual value.

Sample Test case:

Input: 1 -> -2 -> 3 -> -4 -> -8 -> 9
Output: -8 -> -4 -> -2 -> 1 -> 3 -> 9

Note: Expected TC O(n) and O(1) extra space.

I had told 2 approaches for this problem, he was satisfied with my answers. 

25 students were selected for the next round.

Round 3 (Technical Round 2): This round was also conducted by a Senior Software Engineer for 45 minutes. The interviewer told me to open any ide of my choice and then some DSA questions.

1. Check whether the second string can be formed from characters of the first string and also maintain the order in which characters appear.

   Sample Test case:

   A: Today is my interview, so I will be there on time.
   B: interns

   Explanation: String B can be formed by characters of string A by maintaining the order in which they appear.

   Note: Expected TC O(n) and O(1) extra space.

   First, I start with the brute force approach then I tell him DP solution and finally I used a greedy approach.  The interviewer gave me a few hints for the last approach.

2. Zigzag tree traversal. I solve this question very easily by two stack approach.  After that, he asked me about the page fault.

15 students were selected for the next round.

Round 4 (Technical Round 3): This round was conducted by a technical lead for 45 minutes. First, he asked me about my recent development work and then asked me to show the code. 

1. After this, he told me to write the fully functional code of reverse a linked list by using both recursive and iterative approach. He has given me 10 minutes time to complete this without any error. 
2. Then he asked me to write SQL queries on inner join and aggregation.

Finally, he asked about ACID properties.

Verdict: SELECTED

11 students were finally selected.

Advice: Be calm and confident. If you stuck at any question ask for a hint and always focus on what your interviewer is saying. In my resume, I have written too many technologies that were not connected in any manner so try to put only those technologies which fit for the role or in which you are most confident.

Thanks, GeeksforGeeks for providing such a wonderful platform.