Introduction

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

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)

We began with introductions and a discussion about my work and projects for about 10 minutes. For the next 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.

For the coding challenge, I was asked to solve 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)

This round started with introductions and a detailed discussion of my current work and projects for about 20 minutes.

Question 1: Low-Level Algorithmic Discussion (1 hour)

I was presented with a scenario involving 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. My task was to design an algorithm to address this screen tearing. 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)

I was asked to design a text editor that supports up to 10 undo/redo operations.

Initial Assumption: Users cannot edit previously written letters. A follow-up question asked how I would modify the design to allow editing and deleting.

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)

The interview began with introductions. While I anticipated a technical round, the hiring manager posed two distinct questions:

Question 1: Door Flip Puzzle

I was given a scenario with 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?

I solved this quickly, identifying perfect squares as the answer, providing an example for N = 10, and proving it generally by stating that doors with an odd number of factors will be open.

Question 2: Divisibility Rule of 11

I was asked to explain the divisibility rule of 11. I presented a clear explanation.

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

Overall Feedback and Result

The next business day, I received a hire via email, and compensation details were finalized within 3-4 days. I humbly declined the offer from Qualcomm, as I had also received a competing offer from Amazon around the same time, which I ultimately accepted.