PhonePe || Backend (3-5 years) || Interview Experience – Software Engineer Interview Experience
Summary
I completed a machine‑coding LLD round designing a logger library and was selected for a second round, but my incomplete solution to a black‑box test suite problem led to rejection.
Full Experience
Round 1 – Machine Coding / LLD
The first round was a Machine Coding / LLD round.
I was given a problem to design and implement a Logger Library. I had around 6 hours to complete the coding assignment and submit the solution to HR in ZIP format.
After submission, there was around 1 hour of discussion with the interviewer about the implementation.
We discussed:
- Overall design and approach
- Class structure and responsibilities
- Design decisions
- Edge cases
- Possible improvements and extensions
The interviewer suggested a few improvements during the discussion, and I incorporated them into the solution.
The final expectation was to provide runnable code with the discussed improvements.
Result: Selected for Round 2.
Round 2 – DSA / Problem Solving
The second round was a DSA / problem‑solving round.
The question was based on a black‑box test suite / group testing problem.
We are given N test cases and exactly 2 test cases are always failing. We don't know which two.
We can call:
testSuite(list_of_test_ids)
The function returns:
FAIL → if both failing test cases are present in the list
PASS → if either one or both of them are missing
The task was to identify the two failing test cases while minimizing the number of calls to testSuite().
I initially explained a sliding‑window‑based approach with O(N) time complexity.
The interviewer asked whether the number of test‑suite calls could be optimized further.
I then explored a binary‑search‑based approach and explained the reasoning and different cases. However, while implementing the approach, my code was failing for a few edge cases.
I spent the remaining time trying to debug and validate the approach, but the interview ended before I could get the complete solution working.
Closest to this - https://openurl.ebsco.com/EPDB%3Agcd%3A13%3A28383917/detailv2?id=ebsco%3Agcd%3A28074185&jrnl=14789906&sid=ebsco%3Aplink%3Acrawler&link_origin=chatgpt.com
Result: Rejected.
Interview Questions (1)
Identify Two Failing Test Cases with Minimal Calls
Given N test cases where exactly two are failing, you can query a black‑box function testSuite(list_of_test_ids). The function returns FAIL if both failing test cases are present in the supplied list, otherwise it returns PASS. The goal is to determine the identities of the two failing test cases while minimizing the number of calls to testSuite(). Provide an algorithm that identifies both failing cases efficiently.