D. E. Shaw Interview Experience for Summer Intern 2022 | On-Campus

DE Shaw visited our campus (VJTI, Mumbai) in the first week of August 2021 for a 2-month software development internship.

Round 1: Coding Test

Number of questions: 3 Coding questions

Each question had a separate timer, and it wasn’t allowed to attempt the previous questions once the timer ran out. Switching between questions wasn’t allowed either.

1. You have been given an N-sized array of product numbers and another N-sized array of the product cost for those N elements respectively. There can be multiple products of the same product number with different costs. You need to find the maximum cost we can get by selecting one product of each product number. So you cannot select multiple products of the same product number.
2. You are given an NxM matrix. The cells contain *(asterisk) or .(dot) Here, ‘*’ means land, and ‘.’ means water. You need to find the maximum one of all the minimum area rectangles that can completely enclose an island. Neighboring * forms an island (Top, Left, Right, Bottom). The minimum area rectangle can have water in it but should contain an island completely within itself.
3. You have been given N strings, you need to create a minimum length string such that those N strings are substrings of that output string. Extra condition: Let’s consider 2 strings A and B from the given list, if A is before B in the list then in the output string, B should start after the start of A.

Round 2: Technical Interview 1 

This round started with a standard ‘tell-me-about-yourself’ question. 

Next, he asked me questions regarding my previous internship. The discussion went on for 5 – 10 minutes.

I was only asked to write pseudocodes in this round.

1. https://www.geeksforgeeks.org/minimum-number-of-jumps-to-reach-end-of-a-given-array/
2. https://www.geeksforgeeks.org/design-a-stack-that-supports-getmin-in-o1-time-and-o1-extra-space/
3. The third question was related to DFS/BFS in a grid.

I was able to provide optimal solutions to all questions.

OOPs:

1. Questions about polymorphism – its types, ways in which polymorphism can be achieved, etc.
2. A few questions about Inheritance.

DBMS:

1. Explain the need for normalization.
2. Explain 1NF, 2NF, 3NF using a university database example.
3. Write the query to find the maximum salary for every department from a table (Basically use of group by clause)
4. Questions related to indexing (internal structure — eg Btree, B+Tree)
5. Difference between clustered and non-clustered indexes.

OS:

1. Virtual memory and how it is implemented.
2. I was given a scenario and was asked how virtual memory will work in that scenario.

A few more questions were asked from OOPs, DBMS, and OS which I don’t remember exactly. In the end, he asked me if I had any questions. I asked him about the technologies used by an Intern and the job description for an intern.

Round 3: Technical Interview 2

He first asked me about my most recent project — brief description, tech stack, challenges faced, etc.

Kadane’s algorithm – I was asked to code the algorithm and also dry-run it on an example. 

Follow-up question – https://www.geeksforgeeks.org/k-th-largest-sum-contiguous-subarray/ 

I was asked time complexity, space complexity as well a few basic mathematical questions related to the number of pairs possible, etc. I could provide the optimal approach to the question although I did make a few mistakes here and there while mentioning the exact time complexity. But the interviewers were helpful and provided hints whenever it was necessary. 

The second question was a puzzle, didn’t have to code anything. Make sure you understand the question well though. I misunderstood the question and ended up giving the wrong solution initially. The interviewer later re-explained the question to me. 

OOPs:

1. Inheritance and virtual keyword.
2. vptr and vtable.
3. size of an object without any data members.
4. static keyword
5. I was asked to debug an OOPs code snippet as well.
6. Questions related to polymorphism.
7. Basic questions of OOPs like what is class, what is an object, what are the main concepts of OOPs.

OS: This time some really good and in-depth questions related to fork system call and virtual memory were asked.

A few more questions on core subjects were asked that I don’t recall.

No DBMS questions were asked to me in this round, although a few students were asked questions related to DBMS.

In the end, he asked me if I had any questions. This time, I asked him for a few projects that were done by my last year interns and how the projects were distributed among interns. The interviewer was very kind and explained 2 of the previous projects to me.

After this round, 3 students received offer letters, and I was fortunate enough to be one of them.