Introduction

In March 2024, I had the opportunity to interview with Qualcomm for the position of Senior Engineer in their Display team. Having 3.2 years of prior experience as an SDE 2 at a product-based MNC, I was excited to explore this new opportunity. Here’s a detailed account of my interview journey.

Application and Initial Contact

I applied through Qualcomm’s career page in late February. Within 10 days, I received a call from a recruiter. The interview process moved swiftly, with the first two rounds scheduled back-to-back on the same day. Surprisingly, there were no written or online assessments.

Company: Qualcomm
Position: Senior Engineer
Team: Display
Date: March 2024
Offer Date: 1st week of April 2024

Round 1: Coding (1 hour 10 minutes)

Introduction and Project Discussion (10 minutes): We began with introductions and a conversation about my work and projects.
Technical Discussion (45 minutes): We delved into fundamental C++ and C concepts, including processes, threads, dangling pointers, etc. We covered polymorphism in detail, including types, examples, and code samples. Virtual and friend keywords were also discussed. The technical discussion involved MCQ-style questions on code output, compilation and run time errors.
Coding Challenge: Merge k sorted lists. I wrote the entire solution on a shared whiteboard, followed by a time complexity analysis and code walkthrough.

Round 2: Design (2 hours 5 minutes)

Introduction and Project Discussion (20 minutes): We started with introductions, followed by a detailed discussion of my current work and projects.
Question 1: Low-Level Algorithmic Discussion (1 hour)

Scenario: Consider a CRT display panel and an SoC chipset. Both share a single memory buffer: the SoC writes the next frame (producer), and the panel reads from it (consumer). Assume 120 FPS and a 1ms turnaround time (TAT). In CRT technology, the panel displays frames line by line. Imagine the previous frame showed an "A" and the new frame needs a "V." During line-by-line display, if someone takes a screenshot, it might capture parts of both frames (like "> < "), causing screen tearing.

Task: Design an algorithm to address screen tearing.

Approach: I presented three distinct solutions, each with its advantages and disadvantages. We had a thorough discussion about synchronization, similar to the reader-writer problem.
Question 2: Low-Level Design (30 minutes)
Task: Design a text editor that supports up to 10 undo/redo operations.
Initial Assumption: Users cannot edit previously written letters.
Follow-Up Question: How would you modify the design to allow editing and deleting?
Closing Discussion (5 minutes): The final five minutes were reserved for any questions I had.

Intermediate Feedback:

Within two hours, HR contacted me to inform me of positive feedback and schedule a third round. I requested it to be held the next day.

Round 3 (Hiring Manager) (25 minutes)

Introduction: The interview began with introductions.
Unexpected Turn
While I anticipated a technical round, the hiring manager posed the following two questions:
Question 1: Door Flip Puzzle
Scenario: You are given N doors, all initially closed. There are also N people numbered from 1 to N.
- Person 1 flips all doors that are multiples of 1.
- Person 2 flips all doors that are multiples of 2.
- ...
- Person N flips all doors that are multiples of N.
Task: Which doors will remain open after all N steps?
Solution: Perfect squares. I solved this quickly, providing an example for N = 10 and proving it generally: doors with an odd number of factors will be open.
Question 2: Divisibility Rule of 11
Task: Explain the divisibility rule of 11.
Response: I presented a clear explanation (not included for brevity).

The interview was scheduled for 45 minutes but concluded within 25 minutes. The hiring manager provided verbal positive feedback.

Overall Feedback

The next business day, I received an hire via email. Compensation details were finalized within 3-4 days.

Result:

Humbly declined the offer with a counteroffer from Amazon. At the same time, the Amazon process was also ongoing, and I received a hire from Amazon within a week of the offer from Qualcomm.

References:

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