# Middle
**Role:** Software Engineer · **Level:** 18
**Company:** [Ozon](https://scaleengineer.com/companies/ozon)
**Difficulty:** Medium
**Salary:** US$80000 - US$120000
**Experience:** 2 - 5
**Timeline:** ~7 days
The interview process for a Middle Software Engineer at Ozon is designed to assess a candidate's technical proficiency, problem-solving skills, 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/ozon/18-software-engineer
---
## Overall evaluation

- Technical Skills
- Coding and Implementation
- System Design
- Communication and Collaboration
- Cultural Fit

## Questions asked

- Write a function to find the kth largest element in an unsorted array.
- Design a URL shortening service like bit.ly.
- Explain the difference between a process and a thread.
- How would you optimize a slow database query?
- Tell me about a time you had to mentor a junior engineer.
- What are your strengths and weaknesses as a software engineer?
- Describe a situation where you had to deal with ambiguity in requirements.

## Preparation tips

### lists

- Review fundamental data structures and algorithms.
- Practice coding problems on platforms like LeetCode or HackerRank.
- Study common system design patterns and principles.
- Prepare to discuss your past projects and technical challenges in detail.
- Research Ozon's products, services, and company culture.
- Prepare questions to ask the interviewer about the role and the company.

### studyPlan

- {"title":"Data Structures and Algorithms","longDescription":"Weeks 1-2: Focus on core data structures (arrays, linked lists, trees, graphs, hash maps) and algorithms (sorting, searching, dynamic programming, recursion). Practice implementing these in your preferred language. Understand time and space complexity (Big O notation).","shortDescription":"Weeks 1-2: Data Structures & Algorithms fundamentals. Practice coding."}
- {"title":"System Design","longDescription":"Weeks 3-4: Dive into system design concepts. Study topics like scalability, availability, reliability, databases (SQL vs. NoSQL), caching, load balancing, message queues, and API design. Review common design patterns.","shortDescription":"Weeks 3-4: System Design principles and patterns. Scalability and databases."}
- {"title":"Behavioral Preparation","longDescription":"Week 5: Prepare for behavioral questions. Think about your past experiences related to teamwork, problem-solving, conflict resolution, and leadership. Use the STAR method (Situation, Task, Action, Result) to structure your answers.","shortDescription":"Week 5: Behavioral questions preparation. Use STAR method."}
- {"title":"Coding Practice and Resume Review","longDescription":"Week 6: Practice coding challenges that integrate multiple concepts. Refine your understanding of object-oriented programming (OOP) principles and design patterns. Review your resume and be ready to discuss any project in detail.","shortDescription":"Week 6: Integrated coding practice. OOP and resume review."}
- {"title":"Final Preparation","longDescription":"Week 7: Mock interviews with peers or mentors. Focus on communication and clarity. Finalize any questions you want to ask the interviewers. Ensure you are familiar with Ozon's tech stack and recent news.","shortDescription":"Week 7: Mock interviews, communication refinement, and company research."}

## Location differences

- {"location":"Moscow","differences":{"tips":["Research Ozon's presence and operations in this specific region.","Be prepared to discuss projects relevant to the local market.","Highlight any experience working with international teams or in diverse cultural environments."],"interviewFocus":["Understanding of local market nuances and user behavior.","Adaptability to specific regional technical challenges.","Communication skills in the local language and cultural context."],"commonQuestions":["How would you handle a sudden surge in traffic on our platform?","Describe a challenging bug you encountered and how you resolved it.","What are your thoughts on microservices architecture?","How do you ensure code quality and maintainability?","Tell me about a time you had to work with a difficult stakeholder."]}}
- {"location":"Remote","differences":{"tips":["Familiarize yourself with Ozon's global technology stack.","Prepare to discuss your contributions to large-scale projects.","Showcase your ability to collaborate effectively in a remote or international setting."],"interviewFocus":["Deep understanding of scalable system design.","Proficiency in specific technologies prevalent in the region.","Ability to contribute to global product development."],"commonQuestions":["How do you approach performance optimization in a distributed system?","Explain the trade-offs between different database technologies.","Describe your experience with cloud platforms (AWS, Azure, GCP).","How do you stay updated with the latest technology trends?","Tell me about a time you disagreed with your team lead."]}}

## Round 1: HR Screening
**Type:** HR Screening · **Difficulty:** Easy · **Duration:** 30 min
Initial screening to assess basic fit and motivation.
The initial HR screening is a brief conversation to understand your background, motivation for applying, and basic fit with Ozon's culture and the role's requirements. They will also discuss salary expectations and the overall interview process.
**Interviewers look for:** Enthusiasm for the role and company; Clear communication; Basic understanding of software engineering principles; Professionalism
**Evaluation criteria:** Basic understanding of the role; Motivation for applying; Communication clarity; Alignment with company values
**Common rejection reasons:** Poor communication skills; Lack of enthusiasm; Unrealistic salary expectations; Not a good cultural fit
## Questions

- Tell me about yourself.
- Why are you interested in Ozon?
- What are your salary expectations?
- What are your strengths and weaknesses?

## Preparation tips

- Be prepared to talk about your resume and career goals.
- Research Ozon's mission, values, and recent achievements.
- Think about why you are interested in this specific role at Ozon.
- Prepare a few questions to ask the recruiter.

## Round 2: Coding Challenge
**Type:** Technical Interview - Coding · **Difficulty:** Medium · **Duration:** 60 min
Assess coding skills and problem-solving abilities with algorithmic challenges.
This technical round focuses on your ability to solve coding problems. You will be asked to write code to solve specific algorithmic challenges. The interviewer will assess your understanding of data structures, algorithms, and your ability to write clean, efficient, and bug-free code.
**Interviewers look for:** Logical thinking; Correct and efficient implementation of algorithms; Clean and readable code; Ability to communicate the solution approach
**Evaluation criteria:** Problem-solving skills; Algorithmic knowledge; Coding proficiency; Code clarity and efficiency; Ability to articulate thought process
**Common rejection reasons:** Inability to solve coding problems efficiently; Poor code quality; Lack of understanding of fundamental data structures and algorithms; Difficulty explaining thought process
## Questions

- Given a binary tree, find its inorder traversal.
- Implement a function to reverse a linked list.
- Find the two numbers in an array that add up to a specific target.
- Write a function to check if a string is a palindrome.

## Preparation tips

- Practice coding problems on platforms like LeetCode, HackerRank, or Coderbyte.
- Focus on common data structures (arrays, linked lists, trees, graphs, hash maps) and algorithms (sorting, searching, dynamic programming).
- Be prepared to explain your approach and analyze the time and space complexity of your solution.
- Practice coding in a language you are comfortable with.

## Round 3: System Design
**Type:** Technical Interview - System Design · **Difficulty:** Hard · **Duration:** 60 min
Assess ability to design scalable and robust software systems.
This round evaluates your ability to design scalable and robust software systems. You'll be presented with a high-level problem (e.g., design a URL shortener, a social media feed, or a ride-sharing service) and expected to propose a system architecture, discussing components, data flow, databases, APIs, and scalability considerations.
**Interviewers look for:** Ability to design complex systems from scratch; Understanding of distributed systems principles; Sound reasoning for design choices; Ability to discuss trade-offs and alternatives
**Evaluation criteria:** System design capabilities; Understanding of scalability, availability, and reliability; Knowledge of architectural patterns; Ability to handle trade-offs; Consideration of edge cases and failure modes
**Common rejection reasons:** Inability to design scalable systems; Lack of understanding of distributed systems concepts; Poor trade-off analysis; Not considering edge cases or failure scenarios
## Questions

- Design a system like Twitter's news feed.
- Design a rate limiter.
- How would you design a distributed cache?
- Design an API for a ride-sharing service.

## Preparation tips

- Study common system design patterns (e.g., microservices, load balancing, caching, message queues).
- Understand database choices (SQL vs. NoSQL) and their trade-offs.
- Practice designing systems for scale and high availability.
- Be prepared to discuss trade-offs and justify your design decisions.
- Review resources like 'Grokking the System Design Interview'.

## Round 4: Hiring Manager Interview
**Type:** Managerial Interview · **Difficulty:** Medium · **Duration:** 45 min
Assess team fit, collaboration, and career aspirations.
The hiring manager interview focuses on your overall fit with the team and Ozon. They will delve deeper into your experience, career goals, and how you handle various work situations. This is also an opportunity for you to ask more in-depth questions about the team, projects, and career growth.
**Interviewers look for:** Ability to work effectively in a team; Proactiveness and ownership; Good communication and interpersonal skills; Alignment with Ozon's values and team dynamics
**Evaluation criteria:** Teamwork and collaboration skills; Problem-solving approach in a team context; Communication and interpersonal skills; Career aspirations and growth potential; Cultural alignment with the team and company
**Common rejection reasons:** Poor communication with the hiring manager; Lack of alignment with team goals; Negative attitude towards past experiences; Not demonstrating leadership potential or ownership
## Questions

- Tell me about a time you had a conflict with a colleague and how you resolved it.
- How do you handle constructive criticism?
- Describe a project you are particularly proud of and your contribution.
- Where do you see yourself in 5 years?

## Preparation tips

- Reflect on your past projects and your role within the team.
- Prepare examples of how you collaborate, handle conflicts, and contribute to team success.
- Think about your career goals and how this role aligns with them.
- Be ready to discuss your understanding of Ozon's culture and values.
- Prepare thoughtful questions for the hiring manager.