# Software Engineer
**Role:** Software Engineer · **Level:** Software Engineer II
**Company:** [Canonical](https://scaleengineer.com/companies/canonical)
**Difficulty:** Medium to Hard
**Salary:** US$90000 - US$130000
**Experience:** 2 - 5
**Timeline:** ~7 days
This interview process for a Software Engineer II at Canonical is designed to assess a candidate's technical proficiency, problem-solving abilities, and cultural fit within the company. It typically involves multiple rounds, starting with an HR screening, followed by technical interviews focusing on data structures, algorithms, system design, and coding, and concluding with a managerial or team-fit interview.
Canonical: https://scaleengineer.com/interviews/canonical/software-engineer-ii-software-engineer
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## Overall evaluation

- Technical Proficiency
- Communication and Collaboration
- Cultural Fit and Motivation

## Questions asked

- Given an array of integers, find the contiguous subarray with the largest sum.
- Design a system to count the number of views for a given URL.
- Explain the difference between a process and a thread.
- How would you optimize a slow database query?
- Describe a time you had to deal with a difficult teammate.
- What are your strengths and weaknesses as a software engineer?
- Write a function to reverse a linked list.
- How do you ensure the quality of your code?
- What is garbage collection and how does it work?
- Tell me about a project you are particularly proud of.

## Preparation tips

### lists

- Review fundamental data structures (arrays, linked lists, trees, graphs, hash maps) and algorithms (sorting, searching, dynamic programming, graph traversal).
- Practice coding problems on platforms like LeetCode, HackerRank, or Coderbyte, focusing on medium to hard difficulty.
- Study system design principles, common design patterns, and trade-offs for building scalable and reliable systems.
- Understand core concepts of operating systems, networking, and databases.
- Prepare to discuss your past projects in detail, focusing on your contributions, challenges, and learnings.
- Research Canonical's products (Ubuntu, LXD, Juju, MAAS, etc.) and their underlying technologies.
- Prepare for behavioral questions by thinking about the STAR method (Situation, Task, Action, Result) for common scenarios like teamwork, conflict resolution, and handling failure.
- Be ready to explain your thought process clearly and concisely during technical discussions.

### studyPlan

- {"title":"Data Structures and Algorithms","longDescription":"Weeks 1-2: Focus on core data structures and algorithms. Cover arrays, linked lists, stacks, queues, trees (binary, BST, AVL), heaps, hash tables. Implement common sorting and searching algorithms. Practice problems related to these topics on platforms like LeetCode.","shortDescription":"Weeks 1-2: Data Structures & Algorithms Fundamentals. Practice coding problems."}
- {"title":"System Design","longDescription":"Weeks 3-4: Dive into system design. Study concepts like load balancing, caching, database design (SQL vs. NoSQL), message queues, microservices architecture, and distributed systems. Review common system design interview questions and practice designing systems.","shortDescription":"Weeks 3-4: System Design Principles. Practice designing scalable systems."}
- {"title":"Core CS Concepts","longDescription":"Week 5: Brush up on operating systems concepts (processes, threads, memory management, concurrency), networking fundamentals (TCP/IP, HTTP), and database concepts. Review common interview questions related to these areas.","shortDescription":"Week 5: OS, Networking, Databases. Review core concepts."}
- {"title":"Behavioral and Cultural Fit","longDescription":"Week 6: Prepare for behavioral and situational questions. Reflect on past projects and experiences using the STAR method. Research Canonical's values and mission, and think about how your experiences align.","shortDescription":"Week 6: Behavioral Questions & Company Research. Prepare STAR stories."}
- {"title":"Practice and Refinement","longDescription":"Week 7: Mock interviews and final review. Practice coding problems under timed conditions. Conduct mock interviews with peers or mentors to simulate the interview environment and get feedback.","shortDescription":"Week 7: Mock Interviews & Final Review. Practice coding under pressure."}

## Location differences

- {"location":"Remote","differences":{"tips":["Research Canonical's presence and projects in your specific region.","Highlight any experience with open-source contributions, especially if relevant to Canonical's work.","Be prepared to discuss how your problem-solving approach aligns with the local team's working style."],"interviewFocus":["System design and scalability are often emphasized more in interviews for roles based in regions with a strong focus on cloud infrastructure and large-scale deployments.","Candidates in regions with a strong open-source community presence might be asked more about their contributions and understanding of open-source principles.","Behavioral questions might be tailored to reflect local work culture and team dynamics."],"commonQuestions":["How would you design a distributed caching system?","Explain the CAP theorem and its implications.","Describe a challenging bug you encountered and how you debugged it.","What are your thoughts on microservices vs. monolith architecture?","How do you handle concurrency in your code?"]}}
- {"location":"On-site (e.g., London, Montreal)","differences":{"tips":["Familiarize yourself with Canonical's products and their use cases.","Be ready to engage in live coding exercises and whiteboard discussions.","Prepare to articulate how your skills can contribute to Canonical's goals in your region."],"interviewFocus":["For on-site interviews, there might be a greater emphasis on collaborative problem-solving and whiteboard sessions.","Technical depth in specific areas relevant to the local office's projects might be probed more deeply.","Understanding of Canonical's product suite and its applications in the local market could be a focus."],"commonQuestions":["Design an API for a URL shortening service.","How would you implement a rate limiter?","Discuss the trade-offs between SQL and NoSQL databases.","Explain the concept of eventual consistency.","What are the principles of SOLID design?"]}}

## Round 0: HR Screening and Introduction
**Type:** HR Screening · **Difficulty:** Easy · **Duration:** 15 min
Initial screening to assess basic fit and logistics.
This is typically the first point of contact. The HR representative will discuss your background, understand your motivations, and provide an overview of the role and the interview process. They will also cover logistical aspects like salary expectations and availability. This is a good opportunity to ask general questions about Canonical and the position.
**Interviewers look for:** Enthusiasm for the role; Clear understanding of the next steps; Professionalism
**Evaluation criteria:** Understanding of the role and responsibilities; Alignment on compensation and benefits; Logistics and availability
**Common rejection reasons:** Lack of alignment on salary expectations; Poor understanding of the role's responsibilities; Unrealistic expectations about the work environment
## Questions

- What are your salary expectations for this role?
- Why are you interested in Canonical?
- What is your availability to start?

## Preparation tips

- Be prepared to discuss your salary expectations.
- Have a clear understanding of why you are interested in Canonical.
- Prepare questions about the company culture, benefits, and the overall hiring process.

## Round 1: Data Structures and Algorithms Assessment
**Type:** Technical Interview (Data Structures & Algorithms) · **Difficulty:** Medium · **Duration:** 45 min
Assess fundamental CS knowledge with coding problems.
This initial technical round focuses on assessing fundamental computer science knowledge. You will be asked questions related to data structures and algorithms, and you'll likely be expected to write code to solve specific problems, often on a shared online editor or whiteboard. The interviewer will evaluate your problem-solving approach, your understanding of various data structures and algorithms, and your ability to write efficient and correct code.
**Interviewers look for:** Logical thinking; Ability to translate requirements into code; Understanding of time and space complexity; Clean and readable code
**Evaluation criteria:** Problem-solving approach; Algorithmic knowledge; Data structure implementation; Coding clarity and correctness
**Common rejection reasons:** Poor communication of thought process; Inability to solve basic algorithmic problems; Lack of understanding of fundamental data structures; Not asking clarifying questions
## Questions

- Given a binary tree, find its inorder traversal.
- Implement a function to find the kth smallest element in an unsorted array.
- Write a program to detect a cycle in a linked list.

## Preparation tips

- Practice coding problems focusing on arrays, strings, linked lists, trees, graphs, and hash maps.
- Understand and be able to implement common algorithms like sorting, searching, and dynamic programming.
- Analyze the time and space complexity of your solutions.
- Practice explaining your thought process clearly while coding.

## Round 2: System Design and Architecture
**Type:** System Design Interview · **Difficulty:** Hard · **Duration:** 60 min
Assess ability to design scalable software systems.
This round evaluates your ability to design and architect software systems. You'll be presented with a high-level problem (e.g., design Twitter's feed, design a URL shortener) and expected to break it down, discuss various components, data models, APIs, and scalability considerations. The focus is on your thought process, your ability to handle ambiguity, and your understanding of trade-offs in system design.
**Interviewers look for:** Ability to design complex systems; Understanding of distributed system concepts; Pragmatic approach to problem-solving; Clear communication of design decisions
**Evaluation criteria:** System design principles; Scalability and performance considerations; Trade-off analysis; Understanding of distributed systems; API design
**Common rejection reasons:** Inability to design scalable systems; Poor understanding of trade-offs; Lack of consideration for edge cases and failure scenarios; Not being able to justify design choices
## Questions

- Design a system like TinyURL.
- How would you design a real-time notification system?
- Design a distributed key-value store.

## Preparation tips

- Study common system design patterns and architectural styles (e.g., microservices, event-driven).
- Understand concepts like load balancing, caching strategies, database sharding, message queues, and CAP theorem.
- Practice designing various types of systems, from simple APIs to complex distributed platforms.
- Be prepared to discuss trade-offs and justify your design choices.

## Round 3: Behavioral and Team Fit
**Type:** Behavioral and Managerial Interview · **Difficulty:** Medium · **Duration:** 45 min
Assess behavioral aspects, team fit, and motivation.
This round, often conducted by the hiring manager, focuses on your behavioral aspects, past experiences, and overall fit with the team and Canonical's culture. You'll be asked questions about your career goals, how you handle challenges, your strengths and weaknesses, and your motivation for joining Canonical. The interviewer aims to understand how you collaborate, learn, and contribute within a team environment.
**Interviewers look for:** Positive attitude; Ability to work in a team; Self-awareness; Passion for technology and Canonical's mission
**Evaluation criteria:** Teamwork and collaboration skills; Problem-solving approach in real-world scenarios; Communication skills; Alignment with company values; Motivation and career goals
**Common rejection reasons:** Poor cultural fit; Lack of enthusiasm for the role or company; Inability to articulate past experiences effectively; Negative attitude or lack of teamwork potential
## Questions

- Tell me about a time you faced a significant technical challenge and how you overcame it.
- How do you handle disagreements within a team?
- What are you looking for in your next role?

## Preparation tips

- Prepare specific examples from your past experiences using the STAR method.
- Research Canonical's company culture, values, and mission.
- Think about why you want to work at Canonical and for this specific role.
- Be ready to discuss your career aspirations and how this role fits into them.
- Ask thoughtful questions about the team, the role, and the company.