DE Shaw | SDE1 | Hyderabad | Reject

My interview journey for the SDE1 role at DE Shaw began with a recruiter contact via email, followed by a Hackerrank test. The test comprised 8 MCQs covering CS fundamentals, OS, DBMS, and CN, along with 8 aptitude questions focusing on probability and P&C. There were also 3 coding problems, which I felt were LeetCode medium difficulty, each with a strict time constraint. I was only able to get the first question's code fully working and partially coded the other two. I received a rejection email a few days later, but the recruiter contacted me again, stating they liked my resume and shortlisted me for a different team, which restarted the process.

My interviews commenced on a Sunday morning.

Round 1 - Interview

This round started with a coding question: finding the number of subarrays with exactly k odd numbers. I explained the two-pointers approach. Following this, there were questions on OOPs concepts like abstract classes and interfaces, a SQL query, and basic React-related questions, specifically why a React website might experience slow performance.

Round 2 - Analytics/Prob Stat Interview

This round revolved around random number generators. We delved into how they can be implemented and methods to measure their randomness. I discussed concepts like entropy and how to infer randomness from deviations from ideal answers, mentioning weighted sums of probabilities. The interviewer seemed impressed by my thought process and asked me to implement code to calculate deviation, inquiring about tolerable error margins. Subsequently, I was given two puzzles. One involved finding a single bag with heavier coins (1.1g vs 1g) out of 10 bags using a weighing machine, and the other was a standard puzzle. After the puzzles, I was asked to find the longest reward path in a matrix, where movement is restricted to down or right (identified as an introductory DP problem), followed by another SQL query.

Round 3 - DSA Interview

My third round focused heavily on Data Structures and Algorithms. The first question was to find the subarray with the kth largest sum from all possible subarrays of a given array. I proposed an approach using a prefix sum array and maintaining a min-heap of size k for optimization. I started coding, but the interviewer stopped me, seemingly convinced by my approach. We then discussed searching in a rotated sorted array. He then posed a follow-up: how would I solve it if the array could be sorted and rotated in any arbitrary order? I discussed comparing first, last, and middle elements, but struggled a bit with the generalized case. The interviewer suggested moving to a new question. The next problem was to determine if a given string could be formed using words from a provided vector. I explained a Trie-based approach, and when asked for a DP solution, I came up with one and wrote down the pseudocode. Finally, another SQL query was asked, which the interviewer later clarified was related to a correlative subquery.

Round 4

This final round was largely centered on databases, covering topics like normalization, applying normalization to a given database schema, and questions related to OS and OOPs. I mentioned my knowledge of design patterns when asked about Design. More SQL queries were asked at the end. I informed the interviewer that I had learned the core CS syllabus just in the week leading up to the interview, which impressed him given my non-CS background. However, he noted a slight risk associated with my background and that the firm would decide if they wanted to take that risk. I was offered an operations role, but I politely declined, expressing confidence in my ability to handle the learning curve for a development role. It was 5:30 PM, and the recruiter mentioned they would contact me on Monday for the HR round. I received the rejection on Tuesday.

I never anticipated making it to the final round at DE Shaw. The rejection was momentarily disappointing, but the confidence and knowledge I gained through the preparation process were immense. Most interviewers were complimentary, affirming I was on the right track, even if they did consume my entire Sunday. I strongly feel that if companies are hesitant about non-CS backgrounds, they shouldn't extend interview invitations in the first place.