Payu

Role: Software Engineer

College: Not Specified (On-Campus)

Interview Date: Not Specified (Article updated July 23, 2025)

Interview Type: On-Campus

Result: Selected

Difficulty: Medium to Hard

Rounds: Online Test + 4 Technical Rounds + 1 HR Round

Topics Asked: Data Structures, Algorithms, DBMS, OS, Design Patterns, Networking, System Design, Problem Solving

Experience:

PayU visited the campus for recruitment. The selection process included an Online Test, four Technical Rounds, and one HR Round.

Online Test: Consisted of 15 technical MCQs and 5 coding questions. The candidate solved all coding questions and about 10 technical questions, leading to a shortlist for personal interviews.

Technical Interview 1 (30 mins):

• Introduce yourself.
• Tell me about your projects.
• Code for a modified Least Common Ancestor (LCA) of two nodes in a BST (complete working code with boundary conditions).
• How is security provided on a network?
• DBMS: Discussion on Normalization and its significance, various Normal Forms (1NF, 2NF, 3NF, BCNF).
• OS: Explain Paging with an example.
• Design Patterns: Implement Singleton Design Pattern (with a hint).
• Some easy questions on Arrays.
• Write code for Vertical Tree Traversal (considering all boundary and test cases).
• "English Dictionary" question (which the candidate had already solved).
• Asked if the candidate had any questions.

Technical Interview 2 (45 mins):

• Introduce yourself.
• Write complete code for insertion and deletion in AVL Trees implemented using maps (candidate mentioned this as a project, but couldn't write complete code, so explained it instead).
• Discussion about how to maintain user sessions on the web.
• Discussion about cookies and their significance.
• Given an array of integers, find all pairs with a given sum K.
• Given an array of integers, find all pairs (a, b) such that (a % b) = k (O(N) solution expected).

Technical Interview 3 (50 mins):

• Given some input and corresponding output, write code to get the required outputs. This round checked understanding of Recursion, base cases, and problem-solving approach. Code was needed for every case, with increasing complexity of inputs.
• How to implement Mutual Friend Feature of Facebook.
• How to implement top 5 friends feature.

Technical Interview 4 (40 mins):

• Introduce yourself.
• What is KMP Algorithm? Write code for the preprocessing function.
• Difference between HTTP and HTTPS.
• Given two strings, remove characters from string1 that appear in string2 in O(N) and constant space (code was needed).
• Modified DP problem of Rod Cutting (no code needed, mathematical equations and DP approach explanation).

HR Round (20 mins):

• Introduce yourself.
• Why PayU?
• Most challenging situation during college projects and how it was solved.
• Strengths.
• Weaknesses.