Citadel Software Engineer Interview Questions + Guide in 2024

Citadel, a leading global financial institution, is renowned for its dynamic approach to investment and financial strategies. With a strong emphasis on technology and innovation, Citadel stands as a prominent player in the industry, consistently pushing boundaries and redefining standards.

This guide will walk you through the interview process, commonly asked Citadel software engineer questions, and valuable tips to help you excel. Dive in to prepare effectively and increase your chances of securing a role at Citadel.

The interview process usually depends on the role and seniority, however, you can expect the following on a Citadel software engineer interview:

Recruiter/Hiring Manager Call Screening

If your CV is shortlisted, a recruiter from Citadel Talent Acquisition Team will make contact and verify key details like your experiences and skill level. Behavioral questions may also be a part of the screening process.

In some cases, the Citadel hiring manager stays present during the screening round to answer your queries about the role and the company itself. They may also indulge in surface-level technical and behavioral discussions.

The whole recruiter call should take about 30 minutes.

Online Assessment (OA)

The initial screening round for the Citadel Software Engineer role consists of an Online Assessment (OA) conducted via HackerRank. The OA usually consists of 2 coding questions to be solved in 90 minutes. The questions may range from Leetcode Medium to Hard difficulty levels. For example:

• 1st Question: Leetcode Hard. Binary Tree Maximum Path Sum
• 2nd Question: Similar to a Leetcode Medium. Minimum Domino Rotations for Equal Row

It’s essential to practice solving similar problems to perform well in this stage.

Technical Interviews

If you pass the OA, the next step typically involves one or more technical interviews. This can include:

• Pair Programming Sessions: Typically involving solving standard Leetcode-style questions with interviewers from various Citadel offices globally. These sessions may span multiple days to accommodate different time zones.

• Face-to-Face Technical Rounds: These involve deep dives into data structures, algorithms, and advanced coding challenges. Some examples from past interviews include implementing a queue using a stack or solving graph-based problems.

• Project Discussions: You may also be asked to discuss past projects, especially those relevant to the role, such as stock prediction models.

Technical rounds generally last about 45 minutes to an hour each.

Onsite Interview Rounds

Following the technical interviews, selected candidates are invited to onsite interview rounds. During this stage:

• Multiple Interview Rounds: You’ll face multiple rounds of interviews covering technical proficiency, project-related questions, and sometimes behavioral aspects. These can vary in length but expect a full day at the Citadel office.

• Behavioral Rounds: These include questions about past experiences, challenges faced in previous roles, and situational problem-solving skills. Interviewers look to understand how you handle conflicts and align with Citadel’s culture.

Typically, interviews at Citadel vary by role and team, but commonly Software Engineer interviews follow a fairly standardized process across these question topics.

1. Write a function search_list to check if a target value is in a linked list.

Write a function, search_list, that returns a boolean indicating if the target value is in the linked_list or not. You receive the head of the linked list, which is a dictionary with keys value and next. If the linked list is empty, you’ll receive None.

2. Write a query to identify users who placed less than 3 orders or ordered less than $500 worth of product.

Write a query to identify the names of users who placed less than 3 orders or ordered less than $500 worth of product. Use the transactions, users, and products tables.

3. Create a function digit_accumulator to sum every digit in a string representing a floating-point number.

You are given a string that represents some floating-point number. Write a function, digit_accumulator, that returns the sum of every digit in the string.

4. Develop a function to parse the most frequent words used in poems.

You’re hired by a literary newspaper to parse the most frequent words used in poems. Poems are given as a list of strings called sentences. Return a dictionary of the frequency that words are used in the poem, processed as lowercase.

5. Write a function rectangle_overlap to determine if two rectangles overlap.

You are given two rectangles a and b each defined by four ordered pairs denoting their corners on the x, y plane. Write a function rectangle_overlap to determine whether or not they overlap. Return True if so, and False otherwise.

6. What’s the probability of forming a triangle from three pieces of a uniformly broken stick?

If you break a stick uniformly at two points, creating three pieces, what’s the probability that a triangle can be formed from the three pieces?

7. How does random forest generate the forest and why use it over logistic regression?

Explain the process of how random forest generates multiple decision trees and why it might be preferred over logistic regression in certain scenarios.

8. When would you use a bagging algorithm versus a boosting algorithm?

Compare two machine learning algorithms and provide examples of tradeoffs between using a bagging algorithm and a boosting algorithm.

9. How would you evaluate and compare two credit risk models for personal loans?

1. Identify the type of model developed by your co-worker for loan approval.
2. Describe how to measure the difference between two credit risk models over a timeframe.
3. List the metrics to track for measuring the success of the new model.

10. What’s the difference between Lasso and Ridge Regression?

Explain the key differences between Lasso and Ridge Regression, focusing on their regularization techniques and impact on model coefficients.

11. What are the key differences between classification models and regression models?

Describe the main differences between classification models and regression models, including their objectives and types of output.

12. What are the Z and t-tests, and when should you use each?

Explain the purpose and differences between Z and t-tests. Describe scenarios where one test is preferred over the other.

13. How would you reformat student test score data for better analysis?

Given datasets with student test scores, identify drawbacks of the current format, suggest improvements, and discuss common issues in “messy” datasets.

14. What metrics would you use to evaluate the value of marketing channels?

For a company selling B2B analytics dashboards, determine which metrics are essential to assess the effectiveness and value of different marketing channels.

15. How would you determine the next partner card for a company?

Using customer spending data, outline the process to identify the most suitable partner for a new credit card offering.

16. How would you verify if a redesigned email campaign increased conversion rates?

Investigate whether a new email journey led to an increase in conversion rates or if other factors contributed to the observed change.

You should plan to brush up on any technical skills and try as many practice interview questions and mock interviews as possible. A few tips for acing your Citadel software engineer interview include:

• Practice Deeply Mathematical Problems: Many candidates found the questions to be deeply mathematical. Focus on practicing both algorithmic questions and fundamental concepts in computer science.

• Prepare for Coding Rounds Thoroughly: Given the difficulty level, ensure you are well-prepared through platforms like Interview Query and be ready to provide business-driving insights with data science.

• Understand the Company and Role: Know why you are applying to Citadel LLC and be clear on how your skills align with their needs. Be ready to discuss your projects and experiences in detail.

What is the average salary for a Software Engineer at Citadel Llc?

What is the hiring timeline at Citadel LLC for the Software Engineer position?

The hiring timeline can vary, but generally, after applying, candidates might receive an OA invitation within a day. If you pass the OA, you’ll move to subsequent technical and behavioral rounds. The overall process could take several weeks, from initial application to final offer, depending on the scheduling of interviews and assessment of performance.

What qualities is Citadel looking for in a Software Engineer candidate?

Citadel seeks individuals with strong problem-solving abilities, advanced coding skills, and a solid understanding of computer science fundamentals. They value experiences that demonstrate your ability to tackle complex technical problems and work collaboratively. Mathematical reasoning and the ability to present your thoughts clearly in behavioral interviews are also important.

Citadel LLC offers a rigorous and challenging interview process for Software Engineer positions, providing candidates with the opportunity to showcase their technical and problem-solving skills. From the online assessments featuring coding questions to various rounds of technical and behavioral interviews, candidates are evaluated on both their skills and their ability to navigate dynamic business scenarios.

For more insights and comprehensive preparation, check out our main Citadel Interview Guide. Dive into detailed interview guides crafted for various roles, including software engineer and other related positions. Visit Interview Query to access all our company interview guides.

Good luck with your interview!