Meta Android Engineer Interview Guide

The Initial Technical Screen at Facebook typically lasts about 45 minutes and consists of the following:

introductions, discussions about your career aspirations, coding problems, and an opportunity for you to ask questions.

• Introductions (5-10 minutes): The interview kicks off with introductions, which usually take about 5-10 minutes. During this time, your interviewer may ask you questions related to Android. They'll want to gauge your familiarity with building for the Android platform. These questions can cover key Android APIs and common challenges faced by Android developers. It's important to be able to answer these questions based on your day-to-day work, so brushing up on core Android APIs is recommended.
  
• Coding Problems (25-35 minutes): The bulk of the interview will involve one or more coding problems. While some questions might be Android-specific, they often focus on data structures and algorithms. You might encounter one longer coding question or several shorter ones. Make sure you practice coding questions from sources like Glassdoor, Careercup, Project Euler, or Facebook Code Lab. The goal is not to solve every question but to become adept at interpreting problems, formulating efficient solutions, and writing bug-free code without the aid of a compiler. Next, review data structures (e.g., lists, arrays, hash tables, stacks, queues, graphs, trees, heaps), algorithms (sorting, searching, BFS, DFS), and understand their big-O complexities. It's essential to practice coding under time pressure and on a whiteboard or with pen and paper, as this simulates the interview conditions. For more preparation, the Meta iOS Engineer Interview Guide can be useful.

You should have a solid grasp of Android development. Understand core concepts like Activities, Views, Fragments, Services, and more. Additionally, be knowledgeable about concurrency, networking, storage, rendering, and other aspects involved in mobile app development.

• Final Minutes (Q&A): The final 5 minutes are usually reserved for you to ask questions to the interviewer. This is an opportunity for you to learn more about Facebook from an engineer's perspective and to show your genuine interest in the company.

For additional technical preparation, consider the Google Android Engineer and Apple iOS Engineer guides.

During the onsite interviews, you'll go through 4 or 5 interviews throughout the day, and they can be broadly categorized into three types: Coding Interview, Design Interview, and Behavioral Interview.

The Coding Interview

The first part, lasting about 5-10 minutes, involves introductions and questions about your Android knowledge. Expect inquiries about your familiarity with Android-specific concepts and APIs.

The next 25-35 minutes are dedicated to solving coding problems. It's important to note that you won't need to memorize solutions for every problem. Instead, focus on understanding problem-solving methods and recognizing patterns. Platforms like LeetCode can be excellent for honing your skills in this area.

To prepare for this, focus on practicing coding problems on platforms like LeetCode. Recognizing patterns is key here; try to understand the methods used to solve different problems rather than memorizing solutions because you won't know the exact problem in advance.

The Design Interview

In the design interview, which lasts 45 minutes, you'll showcase your design skills. This can pertain to systems or products, depending on your background.

Unlike coding interviews, design interviews are more focused on discussing and drawing on a whiteboard. You'll engage in a conversation with the interviewer and present your solution to a broad engineering design problem.

Your interviewer will give you a broad design problem like designing an image downloading library or a chat app. They'll evaluate your solution based on factors like API usage, persistence, error handling (especially network issues), and your ability to adapt to suggestions and feedback.

Google aims to match candidates with interviewers who have relevant expertise. For example, if you're in the Android pipeline and have a specialized background in an area the company is interested in, they'll do their best to pair you with an interviewer who can assess your skills effectively. This tailored approach helps ensure a fair and relevant evaluation.

To prepare effectively for system design interviews, it's important to align your readiness with the level you're being interviewed for. Junior roles may require a basic understanding of design concepts, while more senior roles like IC3 or IC4 expect a deeper dive into system design, potentially designing a significant part of a system with a strong grasp of the chosen area.

It's essential to reflect on your past projects; think about what aspects were easy and what presented challenges. Additionally, it's a good idea to ponder over design questions like "Tell me how you'd design an email client for Android." This question can open up discussions on various aspects, including fetching and storing mail, managing user preferences for notifications, resource optimization on mobile devices, and leveraging Android libraries for implementation.

The Behavioral Interview

The Behavioral Interview at Facebook is quite an interesting mix. It's not your typical behavioral interview; it's part behavioral and part coding interview.

In the behavioral section, you'll be diving into your past work experiences, talking about what motivates you, and tackling a variety of behavioral questions. This is where you get to unpack your resume and share your personal history and motivations with the interviewer. The goal here is to determine if you're a good fit for Meta's unique engineering culture, which thrives on peer-to-peer collaboration, minimal formal processes, and an unstructured approach to problem-solving.

The coding interview is essentially a condensed version of the coding interviews you might have encountered earlier in the interview process. Facebook throws in a coding question during this interview to gather additional insights into your coding skills and abilities. So, in addition to the dedicated coding interviews you'll face, this segment adds another layer of coding evaluation to ensure they get a comprehensive view of your technical capabilities.

Interview Questions

• Given a binary tree, return all paths from the root to the leaves.
• Why do you want to work here?
• Find three integers in the array that add up to a target value provided in the function. Solve it in linear time, as a brute force solution is insufficient to pass the test.
• When closing an app on Android, what is happening in the background?
• Given 'n' representing a range of numbers from 1 through 'n,' and one of those numbers is bad, find the bad number.
• Given an array of numbers and a sum 'k,' find out if there is a continuous sequence of numbers that sums up to 'k.'
• What happens between clicking an app icon and the app being launched?
• What is an AndroidManifest file?
• How do you determine if the elements in an array are monotonic or not?
• A co-worker constantly arrives late to a weekly scheduled meeting. What would you do?
• I'd like to hear about a time when you failed at work.
• What are some ways you use various styles of communication to be effective in sharing your perspectives?