PhonePe · engineering
Preparation guide for Software Engineer positions at PhonePe Private Limited. Covers their Online Assessment → Technical × 2 → System Design → HR process with technical, behavioral, and HR questions.
What is the difference between a stack and a queue? Where would you use each?
Tip: Give a real-world example — undo/redo history for a stack; print spooling for a queue. Then state time complexities.
What is the time complexity of binary search and what is its prerequisite?
Tip: State O(log n) clearly, mention the sorted array prerequisite, and briefly explain why the search space halves each step.
Explain the four pillars of Object-Oriented Programming with one example each.
Tip: Cover Encapsulation, Inheritance, Polymorphism, and Abstraction. One crisp real-world analogy per pillar is more convincing than definitions alone.
What is a deadlock? State the four conditions required for it to occur.
Tip: Name the four Coffman conditions: Mutual Exclusion, Hold and Wait, No Preemption, Circular Wait. Then mention one prevention strategy — resource ordering is the simplest.
What is the difference between TCP and UDP? When would you choose each?
Tip: TCP = reliable, ordered, connection-oriented (HTTP, email). UDP = faster, connectionless, tolerates loss (video streaming, DNS). Contrast with a concrete scenario.
Describe the difference between process and thread. What are the pros and cons of multithreading?
Tip: Emphasise that threads share memory space while processes are isolated. Pros: concurrency, resource sharing. Cons: race conditions, deadlock, harder debugging.
Tell me about a time you had to meet a tight deadline. How did you prioritise?
Tip: Use the STAR method. Show that you broke the task down, communicated blockers early, and delivered a working subset rather than nothing.
Describe a situation where you had to learn a new technology quickly.
Tip: Highlight your learning process: documentation first, a small proof-of-concept, then iteration. Mention how quickly you became productive.
Why do you want to work at [Company]? What do you know about us?
Tip: Research the company before the interview — tech stack, recent product launches, culture values. Generic answers are immediately penalised.
If you discovered a critical bug in production right before a major release, what would you do?
Tip: Show a structured response: assess severity → communicate to lead immediately → decide rollback vs. hotfix → document the incident. Avoid heroics without communication.
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