# DE Shaw Interview Experience for Quality and Test Engineer (On-Campus) 2023

• Difficulty Level : Expert
• Last Updated : 03 Aug, 2022

De Shaw visited our Campus at the beginning of July and this was the process they followed:

Online Screening Round

It consisted of a variety of questions.

• Aptitude Section (14 MCQs, 28 minutes)
• Technical Section (12 MCQs, 17 minutes)
• Coding Section (2 questions, 50 minutes)

The first question was the simple array-based sorting question, Leetcode Easy level – 20 mins

The second question however was a very lengthy and interesting tree-based question. – 30 mins
Reading and understanding the questions themselves took around 10 mins, so a maximum number of students didn’t finish this question. This was a medium-hard question but was very lengthy to type and debug.

1st Interview Round: There were two interviewers, and the interview was quite challenging. It consisted of a Design Question that involved OS concepts, and a Medium level DSA question, which could be solved using an ordered map of pairs.

Question: From a given text, identify various words and prove that the frequency of the words is inversely proportional to the rank of the words. Lower the rank more the frequency.

Solution:Using a map of strings to int, maintain all the count of words, now sort it to find ranks. Now multiply the rank with the frequency, considering the text is huge this will result in a constant value,

After that I was asked for some mathematical puzzles which are as follows:

1. If there are n tennis players, and we are organizing a knockout-type tournament, find the total number of matches, maximum matches played by the winner, and maximum matches played by the 2nd runner.

Solution: I didn’t mug up any formula for this, I simply derived the answer for a smaller test case like 3 and 4. And using the observed pattern, I could easily extrapolate it for a generalized case and it was correct. It will also help in keeping the communication between you and the interviewer in a good flow and everyone will understand the method used.
Here the answer was: Total matches -> n/2 + n/4 + n/8 + … + 1
And the maximum number of matches that a winner could play was: log2(n)

2. If there is a football tournament with n teams, find a total number of matches played considering that each team plays with every other team, one match on their home ground and the other being away. This round also had some HR components within it. I didn’t do very well with the design part, so I was quite skeptical about my selection for the next round. But fortunately, I made it.

Solution: I followed a similar approach for this question as well, when the number of teams is 3: Matches played is 3*2 = 6
Column: Home ground of a particular team

Similarly for 4 teams: we will have 4*3 = 12

So the answer was: n * (n-1)

2nd Interview Round: This round had two DSA questions and a design question.

• It was a knapsack-up question, not very obvious, but it could be brought down to that. The solution was very similar to this

https://practice.geeksforgeeks.org/problems/0-1-knapsack-problem0945/1

• Involves double stack and transferring items from one to the other based on the inputs or actions required. I had to design a browser history system that would work based on the “go back button” and “forward button” of a browser. It was the first time I encountered such a question and had a fun time solving it.

Here’s a related article you can check out:
https://www.geeksforgeeks.org/implementing-backward-and-forward-buttons-of-browser/

I was then asked to design a class diagram and association for an Alexa system for the home. I did well in this interview and was pretty confident about my selection.

Result: I got the selection mail two days later!

Pro Tips:

• Unlike other companies De Shaw conducts its interviews in a coding platform itself, so your code needs to pass all test cases. So have a good grasp of the syntax and follow best practices while coding. You should be comfortable solving Medium level questions within 20 mins and must at least be able to come up with a good approach for Hard Questions.
• Pay attention to your CS Fundamentals (OS, DBMS, OOPS), they will play a crucial role in the selection process.

Good luck!

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