Interview Breakdown

I had two coding interviews, two system design interviews, and one behavioral interview.

Coding Interviews

• Problem 1: Contiguous Sequence Sums to Given Integer
  • Given an array of integers and a target sum, determine if a contiguous subarray sums up to the target.
  • I used a prefix sum approach with a hash set for an efficient solution. Interviewer grilled me on make it O(1) space, and i completely missed a sliding window approach.
• Problem 2: Range Sum in a Binary Search Tree
  • Given a BST and a range [low, high], return the sum of all values in the BST within that range.
  • I used a DFS approach to traverse the tree and accumulate the sum efficiently.
• Problem 3: Copy Linked List with Random Pointer
  • Given a singly linked list where each node has an additional random pointer, create a deep copy of the list.
  • I implemented both a hashmap-based approach and an in-place modification strategy. I also mentioned the interweaven approach
• Problem 4: Populate Next Pointer in a Binary Tree
  • Given a binary tree, populate each node’s next pointer to its right neighbor at the same level.
  • I used a level-order traversal approach with a queue to link nodes efficiently.

System Design Interviews

• LeetCode System Design
  • Discussed how to design an online coding judge that supports multiple concurrent competitions.
  • Focused on scalable architecture, leaderboard updates, and handling real-time scoring.
• Ad Click Aggregator
  • Designed a system to aggregate ad clicks and generate real-time analytics for advertisers.
  • Discussed event-driven architecture, partitioning strategies, and data consistency challenges.

Behavioral Interview

The interviewer asked a mix of high-level and deep-dive questions, including:
• Tell me about yourself
• The project you’re most proud of
• The most difficult person you had to deal with
• Many follow-up questions digging deeper into my responses

I used CARL (Context, Action, Result, Learning) instead of STAR (Situation, Task, Action, Result) because it aligns with how I process and share information. CARL helped me highlight not just the events but also the key takeaways from each experience.

Outcome

I passed the virtual onsite. The recruiter mentioned that my feedback was positive, and I got the green light for team matching as an E6 (No downgrade)

Key Takeaways & Tips

• Behavioral Mock interviews is the most underated trainning for senior roles – A behavioral mock interview exposed weaknesses in how I communicated impact, especially in cross-team collaboration and business context. This sessions transformed my approach and gave me confidence.
• Don’t undersell your stories – Your experiences are more valuable than you think.
• Clarity and impact matter – Even the best work can be overlooked if not communicated effectively.
• For system design prep, I focused on HelloInterview and BytebyteGo!, I also did two paid mock interviews. The biggest takeaways? Time management—you only have 35 minutes, so you need to pace yourself—and focusing on the right level of detail. For E6, simplicity beats complexity. You don’t need to go deep into API schemas or data models like E4/E5 candidates. Instead, focus on covering all functional components quickly, then go into 3-4 deep dives to make the system truly scalable. Also, you lead the conversation—don’t wait for the interviewer to guide you. If they call something out, it’s probably a signal that could count against you.
• Of course you need to master your craft. It would be way harder if you have not actually built escalable systems before.

Next Steps

I’m currently in team matching. Will keep you posted.