Susquehanna International Group, LLP Software Engineer Interview Questions + Guide in 2025

Susquehanna International Group, LLP (SIG) is a global quantitative trading firm that leverages technology and data to drive its trading strategies and enhance its operational efficiency.

As a Software Engineer at SIG, you will play a critical role in the development and maintenance of systems that support equity trading tools. Your responsibilities will include collaborating with traders to gather requirements, designing and optimizing systems, and implementing new features. You will work with a variety of technologies including C++, C#, PostgreSQL, and SQL Server, contributing to projects that require high performance and stability. The ideal candidate will possess strong object-oriented programming skills, a solid understanding of software development life cycles, and a relentless curiosity to learn and innovate. You should be comfortable in a collaborative environment, where you will work closely with technical analysts and other engineers to create cutting-edge solutions.

Your ability to communicate effectively with both technical and business staff will be essential in this role, as you will be responsible for translating complex requirements into actionable projects. SIG values individuals who are proactive problem solvers, eager to embrace new challenges, and ready to contribute to a dynamic team environment.

This guide will help you prepare for your interview by providing insights into the role and the expectations SIG has for its Software Engineers, allowing you to tailor your responses to align with the company's values and operational processes.

The interview process for a Software Engineer at Susquehanna International Group is structured and thorough, designed to assess both technical skills and cultural fit. The process typically unfolds in several key stages:

1. Initial Phone Screen

The first step involves a phone screening with a recruiter. This conversation usually lasts about 30 minutes and focuses on your background, experience, and motivation for applying to SIG. Expect to discuss your previous roles, technical skills, and how they align with the company's needs. The recruiter may also touch on your interest in the financial services industry and gauge your fit within the company culture.

2. Online Assessment

Following the initial screen, candidates are typically invited to complete an online coding assessment, often hosted on platforms like CodeSignal or Codility. This assessment usually consists of two to four coding problems that test your problem-solving abilities and knowledge of data structures and algorithms. The questions can range from easy to medium difficulty, and candidates are encouraged to practice common coding challenges to prepare.

3. Technical Interview

If you perform well on the online assessment, the next step is a technical interview, which may be conducted over the phone or via video call. This interview typically lasts about an hour and involves in-depth discussions about your coding solutions from the assessment. Interviewers may ask you to explain your thought process, optimize your code, and discuss the time and space complexity of your solutions. Expect questions that cover core programming concepts, object-oriented design, and possibly some language-specific queries based on your expertise.

4. Onsite Interviews

Candidates who successfully navigate the technical interview are often invited for onsite interviews, which can be quite extensive, lasting several hours. This stage usually consists of multiple rounds, including coding exercises, system design challenges, and behavioral interviews. You may be asked to solve problems on a whiteboard or through pair programming with engineers. The focus will be on your ability to write clean, efficient code, as well as your approach to system architecture and design.

5. Final Round and Team Matching

The final round may include a cultural fit interview with team managers or senior engineers. This is an opportunity for you to discuss your career aspirations, work style, and how you would contribute to the team. In some cases, there may also be a team matching process where you can express your preferences for the teams you would like to join based on your interests and skills.

As you prepare for your interview, it's essential to be ready for a variety of technical questions and coding challenges that reflect the skills required for the role. Next, let's delve into the specific interview questions that candidates have encountered during the process.

Here are some tips to help you excel in your interview.

Master the Coding Assessment

The initial coding assessment is a critical step in the interview process at Susquehanna International Group. Expect to encounter medium to hard LeetCode-style questions that test your problem-solving abilities and coding skills. To prepare, practice coding problems on platforms like LeetCode or CodeSignal, focusing on data structures, algorithms, and system design. Familiarize yourself with common patterns and techniques, as well as the specific programming languages mentioned in the job description, such as C++, C#, and Python.

Emphasize Clean Code and Design

During the technical interviews, you will be evaluated not only on your ability to solve problems but also on how well you write clean, efficient code. Be prepared to discuss your thought process and the design choices you make while coding. Interviewers appreciate candidates who can articulate their reasoning and demonstrate a solid understanding of software design principles. Practice explaining your code and design decisions clearly, as communication is key in collaborative environments.

Prepare for Behavioral Questions

While technical skills are essential, Susquehanna also values cultural fit and collaboration. Expect behavioral questions that assess your past experiences, teamwork, and problem-solving approach. Reflect on your previous roles and be ready to discuss specific projects, challenges you faced, and how you overcame them. Highlight your curiosity and willingness to learn, as these traits align well with the company’s growth mindset.

Understand the Company Culture

Susquehanna International Group emphasizes collaboration and innovation. Familiarize yourself with their values and the way they operate. Be prepared to discuss how you can contribute to a team-oriented environment and how your personal values align with the company’s mission. Showing that you understand and appreciate their culture can set you apart from other candidates.

Engage with Your Interviewers

Throughout the interview process, engage with your interviewers by asking insightful questions about the team, projects, and technologies they use. This demonstrates your genuine interest in the role and the company. Additionally, it can provide you with valuable insights into what it’s like to work at Susquehanna, helping you assess if it’s the right fit for you.

Follow Up Professionally

After your interviews, send a thank-you email to express your appreciation for the opportunity to interview. This not only shows your professionalism but also reinforces your interest in the position. If you don’t hear back within a reasonable timeframe, don’t hesitate to follow up politely to inquire about your application status.

By following these tips and preparing thoroughly, you can approach your interview at Susquehanna International Group with confidence and clarity. Good luck!

In this section, we’ll review the various interview questions that might be asked during a software engineering interview at Susquehanna International Group (SIG). The interview process will likely focus on your coding skills, problem-solving abilities, and understanding of software development principles. Be prepared to demonstrate your knowledge of data structures, algorithms, and system design, as well as your ability to communicate effectively with both technical and non-technical stakeholders.

Coding and Algorithms

1. Can you explain the difference between a stack and a queue? When would you use each?

Understanding the fundamental data structures is crucial for any software engineer.

How to Answer

Discuss the characteristics of both data structures, including their operations and use cases. Provide examples of scenarios where one might be preferred over the other.

Example

“A stack follows a Last In First Out (LIFO) principle, making it ideal for scenarios like undo mechanisms in applications. A queue, on the other hand, operates on a First In First Out (FIFO) basis, which is useful for scheduling tasks, such as print jobs in a printer queue.”

2. How would you implement a function to check if a string is a palindrome?

This question tests your understanding of string manipulation and algorithmic thinking.

How to Answer

Outline your approach to solving the problem, including any edge cases you would consider. Discuss the time and space complexity of your solution.

Example

“I would iterate through the string from both ends towards the center, comparing characters. If all corresponding characters match, the string is a palindrome. This approach has a time complexity of O(n) and a space complexity of O(1).”

3. Describe how you would find the K’th largest element in an array.

This question assesses your problem-solving skills and knowledge of algorithms.

How to Answer

Explain the algorithm you would use, such as quickselect or sorting, and discuss its efficiency.

Example

“I would use the quickselect algorithm, which has an average time complexity of O(n). It works by partitioning the array and recursively selecting the K’th largest element until it is found.”

4. Can you explain the concept of Big O notation and provide examples?

Understanding time complexity is essential for evaluating the efficiency of algorithms.

How to Answer

Define Big O notation and provide examples of common complexities, such as O(1), O(n), O(n log n), and O(n^2).

Example

“Big O notation describes the upper limit of an algorithm's running time. For instance, a linear search has a time complexity of O(n), while a binary search has a time complexity of O(log n) because it divides the search space in half with each iteration.”

5. How would you design a system to manage a grocery store's inventory?

This question evaluates your system design skills and ability to think through complex problems.

How to Answer

Discuss the components of the system, including data storage, user interfaces, and interactions with other systems.

Example

“I would design a relational database to store product information, including stock levels and pricing. The system would have a user interface for employees to update inventory and a reporting feature to track sales trends. I would also implement APIs for integration with other systems, such as point-of-sale systems.”

Data Structures

1. What is a hash table, and how does it work?

This question tests your understanding of one of the most commonly used data structures.

How to Answer

Explain the concept of hash tables, including how they store key-value pairs and handle collisions.

Example

“A hash table uses a hash function to compute an index into an array of buckets or slots, from which the desired value can be found. In case of a collision, where two keys hash to the same index, I would use chaining or open addressing to resolve it.”

2. Can you explain the difference between an array and a linked list?

This question assesses your knowledge of basic data structures.

How to Answer

Discuss the characteristics, advantages, and disadvantages of both data structures.

Example

“An array has a fixed size and allows for fast access to elements via indexing, but resizing it can be costly. A linked list, however, is dynamic in size and allows for efficient insertions and deletions, but accessing elements is slower since it requires traversal.”

3. How would you implement a binary search tree?

This question evaluates your understanding of tree data structures and their operations.

How to Answer

Outline the structure of a binary search tree and describe how to implement basic operations like insertion, deletion, and traversal.

Example

“I would create a node class with left and right pointers. For insertion, I would compare the value to be inserted with the current node's value and recursively insert it into the left or right subtree. This ensures that the tree remains sorted.”

4. What is a graph, and how would you represent it in code?

This question tests your understanding of graph theory and data structures.

How to Answer

Discuss different ways to represent graphs, such as adjacency lists and matrices, and when to use each.

Example

“I would represent a graph using an adjacency list for sparse graphs, as it is more memory efficient. Each node would have a list of its neighbors, allowing for efficient traversal and manipulation.”

5. Explain the concept of a binary heap and its applications.

This question assesses your knowledge of advanced data structures.

How to Answer

Define a binary heap and discuss its properties and use cases, such as priority queues.

Example

“A binary heap is a complete binary tree that satisfies the heap property, where the parent node is either greater than or equal to (max heap) or less than or equal to (min heap) its children. It is commonly used to implement priority queues, allowing for efficient retrieval of the highest or lowest priority element.”

System Design

1. How would you design a URL shortening service?

This question evaluates your ability to design scalable systems.

How to Answer

Discuss the components of the system, including how to generate unique keys and store mappings.

Example

“I would create a database to store the original URLs and their corresponding shortened keys. To generate unique keys, I could use a base conversion algorithm on an auto-incrementing ID. The service would also need to handle redirection and track usage statistics.”

2. Describe how you would design a chat application.

This question tests your understanding of real-time communication systems.

How to Answer

Outline the architecture of the application, including client-server interactions and data storage.

Example

“I would use a client-server architecture with WebSocket for real-time communication. The server would handle message routing and storage, while a database would store user profiles and chat histories. I would also implement features like message delivery status and notifications.”

3. How would you approach designing a payment processing system?

This question assesses your ability to design secure and reliable systems.

How to Answer

Discuss the components of the system, including security measures and transaction handling.

Example

“I would design a payment processing system with a focus on security, using encryption for sensitive data and implementing fraud detection mechanisms. The system would handle transaction requests, validate them, and interact with banking APIs to process payments.”

4. Can you explain how you would design a recommendation system?

This question evaluates your understanding of machine learning and data analysis.

How to Answer

Discuss the algorithms you would use and how to gather and process data.

Example

“I would use collaborative filtering to analyze user behavior and preferences. By collecting data on user interactions and applying matrix factorization techniques, I could generate personalized recommendations based on similar users’ preferences.”

5. How would you design a file storage system?

This question tests your ability to design systems that handle large amounts of data.

How to Answer

Outline the architecture of the system, including data storage, retrieval, and redundancy.

Example

“I would design a distributed file storage system that uses sharding to split files across multiple servers for scalability. I would implement redundancy through replication to ensure data availability and durability in case of server failures.”