Paytm

Role: SDE Intern + FTE

College: ABES Engineering College, Ghaziabad

Interview Date: March 2025

Interview Type: On-Campus

Result: Not Specified (Technical interview scheduled after resume shortlisting and assessment)

Difficulty: Medium-Hard

Rounds: 2 coding interview rounds

Topics Asked: Data Structures, Algorithms, OOPs, SQL, DBMS fundamentals

Experience:

The process started with a resume shortlisting round. This was followed by a technical assessment round which included five major questions: three medium-level coding questions and two SQL-based queries.

After a week, the results were declared, and the technical interview was scheduled. There were 2 coding interview rounds, primarily focusing on data structures and algorithms, along with a few questions from OOPs and SQL. Both rounds were conducted virtually via Google Meet. The interviewer provided his own IDE and asked the candidate to share their screen. The candidate was required to write functional code in C++ and explain the time and space complexity of each solution. Additionally, a few questions on database fundamentals were asked. The interview lasted for about 1 hour.

ROUND 1 (Questions):

• "Tell me something about yourself."
• Reverse a Linked List (Code):
  • Without using any extra data structure (used recursion stack)
  • Using pointers
• Find the first non-repeating character in a string (Code)
• Find the lowest common ancestor of two nodes in a Binary Search Tree (Code)
• What are function overloading and function overriding? Explain with examples.
• What are joins in SQL? Explain the different types.
• "Do you have any questions for me?"

ROUND 2 (Questions):

• Find the maximum sum subarray using Kadane's Algorithm (Code)
• Implement LRU Cache (Code)
• Write code and explain its space and time complexity.
• What are the ACID properties in DBMS?
• Differentiate between clustered and non-clustered indexes.
• What are primary keys and foreign keys in SQL?
• Differentiate between BFS and DFS.
• What is polymorphism in OOP? Give an example.
• "Do you have any questions for me?"