Criteo

Software Engineer II

Software EngineerL3Medium

This interview process is for a Software Engineer II (L3) position at Criteo. It is designed to assess a candidate's technical skills, problem-solving abilities, and cultural fit within the company.

Rounds

3

Timeline

~10 days

Experience

2 - 5 yrs

Salary Range

US$100000 - US$130000

Total Duration

150 min

Overall Evaluation Criteria

Technical Proficiency

Problem-solving skills
Algorithmic thinking
Data structures knowledge
Code quality and efficiency
System design capabilities
Communication skills
Teamwork and collaboration
Cultural fit

Communication & Collaboration

Ability to articulate thought process
Clarity of explanations
Active listening
Constructive feedback

Cultural Fit

Alignment with Criteo's values
Proactiveness and initiative
Adaptability and learning agility

Preparation Tips

1Review fundamental data structures and algorithms.
2Practice coding problems on platforms like LeetCode, HackerRank, or Coderbyte.
3Study system design principles and common architectural patterns.
4Understand object-oriented programming concepts.
5Prepare for behavioral questions by reflecting on past experiences using the STAR method.
6Research Criteo's products, services, and company culture.
7Be ready to discuss your resume in detail.

Study Plan

1

Data Structures and Algorithms

Weeks 1-2: Data Structures & Algorithms fundamentals. Practice 5-7 problems/week.

Weeks 1-2: Focus on core data structures (arrays, linked lists, trees, graphs, hash tables) and algorithms (sorting, searching, dynamic programming, recursion). Practice implementing these in your preferred language. Aim for at least 5-7 problems per week.

2

System Design

Weeks 3-4: System Design principles and common patterns. Practice designing systems.

Weeks 3-4: Dive into system design. Study concepts like scalability, availability, consistency, load balancing, caching, databases (SQL vs. NoSQL), and message queues. Review common system design interview questions and practice designing systems like Twitter feed, URL shortener, etc.

3

Behavioral & Situational Questions

Week 5: Behavioral questions preparation using STAR method. Reflect on past experiences.

Week 5: Prepare for behavioral and situational questions. Reflect on your past projects and experiences, identifying examples that demonstrate leadership, teamwork, problem-solving, and handling challenges. Use the STAR method (Situation, Task, Action, Result) to structure your answers.

4

Final Review and Criteo Specifics

Week 6: Review, mock interviews, Criteo research, and prepare questions.

Week 6: Consolidate your learning. Review all topics, practice mock interviews, and research Criteo's specific technologies and culture. Prepare questions to ask the interviewer.

Commonly Asked Questions

Given an array of integers, find the contiguous subarray with the largest sum.
Design a system to store and retrieve user preferences.
Tell me about a time you had to deal with a difficult stakeholder.
How would you optimize a slow database query?
Explain the concept of microservices and their advantages/disadvantages.
Describe a situation where you had to learn a new technology quickly.
What are the trade-offs between using a relational database and a NoSQL database?
How would you design a rate limiter for an API?
Tell me about a project you are particularly proud of.
What is the difference between concurrency and parallelism?

Location-Based Differences

Paris

Interview Focus

Strong emphasis on distributed systems and scalability.Deep dive into system design principles.Understanding of Criteo's specific tech stack (e.g., Java, Scala, distributed caching).

Common Questions

How would you design a URL shortener service?

Explain the difference between SQL and NoSQL databases.

Describe a challenging technical problem you solved and how you approached it.

Tips

Familiarize yourself with common distributed system patterns.
Be prepared to discuss trade-offs in system design choices.
Research Criteo's engineering blog and recent technical publications.

New York

Interview Focus

Focus on data engineering and large-scale data processing.Understanding of machine learning concepts and their application.Experience with big data technologies (e.g., Spark, Hadoop).

Common Questions

How would you implement a real-time bidding system?

Discuss the challenges of handling large-scale data processing.

Describe your experience with cloud platforms like AWS or GCP.

Tips

Review concepts related to data pipelines and ETL processes.
Be ready to explain your experience with cloud-native services.
Understand the basics of ad-tech and its underlying technologies.

Process Timeline

1
Coding Assessment45m
2
System Design60m
3
Behavioral and Managerial Fit45m

Interview Rounds

3-step process with detailed breakdown for each round

1

Coding Assessment

Coding challenge focused on data structures and algorithms.

Technical Interview - CodingMedium
45 minSoftware Engineer

This round focuses on assessing your fundamental programming skills. You will be asked to solve one or two coding problems, typically involving data structures and algorithms. The interviewer will evaluate your ability to write clean, efficient, and correct code, as well as your problem-solving approach and communication skills. You'll be expected to explain your thought process throughout the coding exercise.

What Interviewers Look For

Clean, well-organized code.Logical and systematic approach to problem-solving.Understanding of time and space complexity.Ability to explain the solution and its trade-offs.

Evaluation Criteria

Correctness of the solution
Efficiency of the solution (time and space complexity)
Code readability and maintainability
Problem-solving approach

Questions Asked

Given a binary tree, find its inorder traversal.

Data StructuresTreesRecursion

Implement a function to find the kth smallest element in an unsorted array.

AlgorithmsSortingQuickselect

Write a function to check if a string is a palindrome, ignoring non-alphanumeric characters and case.

StringsTwo Pointers

Preparation Tips

1Practice coding problems focusing on arrays, strings, linked lists, trees, graphs, and hash maps.
2Understand common algorithms like sorting, searching, dynamic programming, and recursion.
3Be comfortable analyzing the time and space complexity of your solutions.
4Practice explaining your code and thought process out loud.

Common Reasons for Rejection

Inability to articulate thought process clearly.
Poorly structured or inefficient code.
Lack of understanding of fundamental data structures and algorithms.
Inability to solve coding problems within the given time.
2

System Design

Design a scalable system, focusing on architecture and trade-offs.

System Design InterviewHard
60 minSenior Software Engineer / Architect

This round evaluates your ability to design complex software systems. You will be presented with a high-level problem (e.g., design a URL shortener, a social media feed, or a distributed cache) and asked to propose a solution. The focus is on your understanding of scalability, availability, data storage, APIs, and trade-offs. You should be prepared to discuss different components, their interactions, and potential bottlenecks.

What Interviewers Look For

Ability to design scalable and reliable systems.Understanding of distributed systems concepts.Knowledge of various architectural patterns and trade-offs.Effective communication of complex ideas.

Evaluation Criteria

System design approach
Scalability and performance considerations
Choice of technologies and data stores
Handling of edge cases and failure scenarios
Clarity and structure of the design

Questions Asked

Design a system like Twitter's news feed.

System DesignScalabilityDistributed Systems

Design a distributed key-value store.

System DesignDistributed SystemsDatabases

How would you design an API for a ride-sharing service?

System DesignAPI DesignMicroservices

Preparation Tips

1Study common system design patterns (e.g., load balancing, caching, database sharding, message queues).
2Review distributed systems concepts (CAP theorem, consistency models).
3Practice designing various systems, considering different requirements and constraints.
4Be prepared to justify your design choices and discuss alternatives.

Common Reasons for Rejection

Lack of clarity in system design.
Failure to consider scalability and edge cases.
Poor understanding of trade-offs in design choices.
Inability to communicate design effectively.
3

Behavioral and Managerial Fit

Assesses past behavior and cultural fit using the STAR method.

Behavioral InterviewMedium
45 minHiring Manager / Team Lead

This interview focuses on your behavioral and situational responses. The hiring manager will ask questions about your past experiences to understand how you handle various work scenarios, such as teamwork, conflict resolution, dealing with failure, and leadership. The goal is to assess your cultural fit and how you align with Criteo's values and working style. Prepare specific examples using the STAR method.

What Interviewers Look For

Evidence of collaboration and teamwork.Ability to handle conflict and challenges constructively.Proactiveness and ownership.Enthusiasm for Criteo and the role.

Evaluation Criteria

Teamwork and collaboration skills
Problem-solving approach in past situations
Adaptability and learning agility
Communication and interpersonal skills
Alignment with Criteo's values

Questions Asked

Tell me about a time you disagreed with a teammate. How did you resolve it?

BehavioralTeamworkConflict Resolution

Describe a challenging project you worked on and how you overcame obstacles.

BehavioralProblem SolvingResilience

How do you prioritize your work when you have multiple competing deadlines?

BehavioralTime ManagementPrioritization

Preparation Tips

1Review your resume and identify key projects and accomplishments.
2Prepare specific examples using the STAR method for common behavioral questions (teamwork, conflict, failure, success, leadership).
3Research Criteo's company culture and values.
4Think about why you want to work at Criteo and what you can contribute.

Common Reasons for Rejection

Lack of self-awareness.
Negative attitude or poor cultural fit.
Inability to provide specific examples for behavioral questions.
Lack of enthusiasm or interest in the role/company.

Commonly Asked DSA Questions

Frequently asked coding questions at Criteo

View all
Two SumEASYValid ParenthesesEASYSearch in Rotated Sorted ArrayMEDIUMMerge Sorted ArrayEASYIntersection of Two ArraysEASYRansom NoteEASYRandom Pick with WeightMEDIUMFlood FillEASY