# Software Engineer
**Role:** Software Engineer · **Level:** L3
**Company:** [LINE](https://scaleengineer.com/companies/line)
**Difficulty:** Medium
**Salary:** US$55000 - US$75000
**Experience:** 1 - 3
**Timeline:** ~14 days
This interview process is for a Software Engineer position at LINE, specifically for the L3 level. It is designed to assess a candidate's technical skills, problem-solving abilities, and cultural fit within the company.
Canonical: https://scaleengineer.com/interviews/line/l3-software-engineer
---
## Overall evaluation

- Technical Skills
- Communication and Soft Skills

## Questions asked

- Given an array of integers, find the contiguous subarray with the largest sum.
- Design a system to count the number of active users on a website in real-time.
- Tell me about a time you disagreed with a teammate. How did you handle it?
- Implement a function to reverse a linked list.
- How would you scale a web application to handle millions of users?
- Describe a project you are particularly proud of and your role in it.
- What are the trade-offs between SQL and NoSQL databases?
- How do you approach learning a new technology?
- Explain the concept of recursion with an example.
- What are your strengths and weaknesses as a software engineer?

## Preparation tips

### lists

- Review fundamental data structures and algorithms (arrays, linked lists, trees, graphs, sorting, searching).
- Practice coding problems on platforms like LeetCode, HackerRank, or Codewars.
- Study common system design concepts (scalability, availability, databases, caching, load balancing).
- Prepare to discuss your past projects and technical challenges you've faced.
- Understand LINE's products and services.
- Research common behavioral interview questions and prepare STAR method responses.
- Practice explaining your solutions and thought process clearly.

### studyPlan

- {"title":"Data Structures and Algorithms Fundamentals","longDescription":"Weeks 1-2: Focus on core data structures (arrays, linked lists, stacks, queues, hash maps) and basic algorithms (sorting, searching). Practice implementing these from scratch and solving problems involving them. Aim for 2-3 problems per day.","shortDescription":"Weeks 1-2: Data Structures & Basic Algorithms. Practice 2-3 problems/day."}
- {"title":"Advanced Algorithms and Complexity Analysis","longDescription":"Weeks 3-4: Dive into more advanced data structures (trees, graphs, heaps) and algorithms (dynamic programming, greedy algorithms, graph traversal). Work on medium-difficulty problems on platforms like LeetCode. Understand time and space complexity analysis.","shortDescription":"Weeks 3-4: Advanced Algorithms & Complexity. Practice medium problems."}
- {"title":"System Design","longDescription":"Weeks 5-6: Focus on System Design. Study concepts like API design, database choices, caching strategies, load balancing, and microservices. Review common system design interview questions and practice designing systems.","shortDescription":"Weeks 5-6: System Design Concepts. Review and practice design problems."}
- {"title":"Behavioral Preparation","longDescription":"Week 7: Behavioral preparation. Prepare answers for common behavioral questions using the STAR method. Reflect on past projects, challenges, and teamwork experiences. Research LINE's company culture and values.","shortDescription":"Week 7: Behavioral Interview Prep. STAR method and company research."}
- {"title":"Mock Interviews and Final Review","longDescription":"Week 8: Mock interviews and review. Conduct mock interviews with peers or mentors to simulate the actual interview environment. Review weak areas identified during practice and mock interviews.","shortDescription":"Week 8: Mock Interviews & Review. Practice and refine weak areas."}

## Location differences

- {"location":"Seoul","differences":{"tips":["Be prepared to discuss specific projects and your contributions in detail.","Familiarize yourself with common system design patterns.","Practice explaining technical concepts clearly and concisely."],"interviewFocus":["Emphasis on practical application of data structures and algorithms in real-world scenarios.","Assessment of understanding of distributed systems and scalability.","Evaluation of communication and collaboration skills."],"commonQuestions":["How would you optimize a database query for a high-traffic e-commerce site?","Describe a challenging bug you encountered and how you debugged it.","Tell me about a time you had to work with a difficult team member."]}}
- {"location":"Tokyo","differences":{"tips":["Review common system design interview questions and frameworks.","Be ready to whiteboard your solutions and explain your thought process.","Highlight any experience with cloud platforms like AWS or GCP."],"interviewFocus":["Focus on system design and architectural thinking.","Evaluation of coding proficiency and clean code principles.","Assessment of problem-solving approach and analytical skills."],"commonQuestions":["Design a URL shortening service.","How would you handle a sudden surge in user traffic?","Describe your experience with agile development methodologies."]}}

## Round 1: HR Screening
**Type:** HR Screening · **Difficulty:** Easy · **Duration:** 45 min
HR screening to assess basic qualifications and cultural fit.
This initial round is conducted by an HR representative or a recruiter to assess your general fit for the role and the company. They will ask about your background, motivation for applying, and basic technical understanding. It's also an opportunity for you to ask questions about the company culture and the role.
**Interviewers look for:** Fundamental programming skills; Logical thinking; Ability to write clean and readable code
**Evaluation criteria:** Basic coding ability; Understanding of data structures; Problem-solving approach
**Common rejection reasons:** Inability to solve basic coding problems.; Poor understanding of fundamental data structures.; Lack of clear communication.; Negative attitude.
## Questions

- Tell me about yourself.
- Why are you interested in LINE?
- What are your strengths and weaknesses?
- Describe a challenging project you worked on.

## Preparation tips

- Be prepared to talk about your resume and career goals.
- Research LINE's mission, values, and products.
- Practice answering common behavioral questions.
- Prepare questions to ask the interviewer.

## Round 2: Technical Coding Interview
**Type:** Data Structures and Algorithms Interview · **Difficulty:** Medium · **Duration:** 60 min
Technical interview focusing on coding problems and algorithms.
This is a technical interview focused on data structures and algorithms. You will be asked to solve coding problems, typically on a shared online editor or whiteboard. The interviewer will assess your ability to analyze problems, choose appropriate data structures and algorithms, write efficient code, and explain your reasoning.
**Interviewers look for:** Ability to translate requirements into code.; Understanding of time and space complexity.; Clean and maintainable code.; Logical approach to problem-solving.
**Evaluation criteria:** Problem-solving skills; Algorithmic thinking; Data structure knowledge; Coding proficiency; Code clarity and efficiency
**Common rejection reasons:** Failure to solve coding problems within the time limit.; Incorrect or inefficient algorithms.; Inability to explain the thought process.; Poor code quality.
## Questions

- Given a binary tree, find its inorder traversal.
- Implement a function to check if a string is a palindrome.
- Find the kth smallest element in a binary search tree.
- Write a function to merge two sorted arrays.

## Preparation tips

- Practice coding problems on platforms like LeetCode (Easy/Medium).
- Review common data structures (arrays, linked lists, trees, graphs) and algorithms (sorting, searching, dynamic programming).
- Focus on understanding time and space complexity (Big O notation).
- Practice explaining your thought process out loud while solving problems.

## Round 3: System Design Interview
**Type:** System Design Interview · **Difficulty:** Medium · **Duration:** 60 min
Assesses ability to design scalable and robust 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 discuss various components, data models, APIs, and scalability strategies. The focus is on your thought process and ability to make reasoned design decisions.
**Interviewers look for:** Ability to design robust and scalable systems.; Understanding of distributed systems concepts.; Knowledge of databases, caching, and load balancing.; Clear communication of design choices.
**Evaluation criteria:** System design skills; Scalability and performance considerations; Trade-off analysis; Problem-solving approach for large-scale systems
**Common rejection reasons:** Lack of understanding of system design principles.; Inability to handle scalability and performance considerations.; Poor trade-off analysis.; Difficulty in communicating complex ideas.
## Questions

- Design a URL shortening service like bit.ly.
- How would you design a news feed system for a social media platform?
- Design a system to handle real-time analytics for a website.
- Discuss the architecture of a distributed key-value store.

## Preparation tips

- Study common system design patterns and concepts.
- Practice designing various systems (e.g., social media feeds, chat applications, e-commerce platforms).
- Understand trade-offs between different technologies and approaches.
- Be prepared to discuss databases, caching, load balancing, and message queues.

## Round 4: Managerial Interview
**Type:** Behavioral and Managerial Interview · **Difficulty:** Medium · **Duration:** 45 min
Managerial interview focusing on behavioral aspects, teamwork, and cultural fit.
This interview is typically with the hiring manager for the team you would be joining. It focuses on your behavioral aspects, teamwork, problem-solving approach in a team context, and overall fit with the team and company culture. They will also discuss your career aspirations and how they align with opportunities at LINE.
**Interviewers look for:** How you handle challenges and conflicts.; Your ability to work effectively in a team.; Your passion for software development.; Alignment with LINE's values.
**Evaluation criteria:** Teamwork and collaboration; Communication skills; Problem-solving approach; Cultural fit; Motivation and career goals
**Common rejection reasons:** Lack of alignment with team values.; Poor communication or collaboration skills.; Unrealistic salary expectations.; Lack of enthusiasm or motivation.
## Questions

- Tell me about a time you had a conflict with a colleague and how you resolved it.
- How do you prioritize your work when you have multiple tasks?
- What are you looking for in your next role?
- Describe a situation where you had to adapt to a change.

## Preparation tips

- Reflect on your past experiences working in teams.
- Prepare examples of how you've handled conflicts or disagreements.
- Think about your career goals and how this role fits into them.
- Show enthusiasm for the role and the company.