Facebook Coding Interview Questions: How to Ace Your Next Interview

        1 years ago

For many IT experts around the world, landing a position at Facebook is a dream career. Working at Facebook is a coveted opportunity with competitive pay, cutting-edge technology, and a world-renowned brand. Competition is fiercer than ever, and Facebook is looking for the best people as it continues to hire hundreds of employees.

The company assesses your broad expertise, cultural match, and capacity to create within constraints. In order to help you in your preparation, we have compiled a list of Facebook coding interview questions for you to ace your next interview.

Facebook Coding Interview: Overview 

To land a job at Facebook, especially for engineers, you need to understand how the company assesses your skills. The more preparation you do, the greater chances will be. So, let's dive deeper into the Facebook coding interview process.

Interview Timeline: This is the timeline to complete a job application from start to finish in 1-2 months, including resume submission and a possible offer.

Interview Types: The interview process usually lasts 6 to 7 interviews. This includes a 20-minute pre-screening interview, a 50-minute technical phone interview (1-2 coding questions), and 4 -5 on-site interviews.

On-site interviews: On-site interviews are 30 minutes long, and the interviewer will ask you one to two coding questions. 

Coding Questions: Coding questions are essential for the interview process. The interviewer will evaluate your problem-solving ability, coding style, and technical skills. It usually takes about 20 minutes to answer one coding question.

Hiring Levels:  For entry-level software jobs at Facebook, the company hires at level E3 and has an elevation of 9 levels ahead. The role of E5 is considered to be entry-level managerial.

Hiring Teams: There are different teams at Facebook, each with its own focus. The main teams are Engineering (Product and Infrastructure), Design (Product and UX), Analytics, Data Science, and Business Product.

Programming languages: Facebook uses a range of programming languages, such as C++, Java, Python, Perl, Ruby, and PHP.

Aspects to Display During the Facebook Coding Interview 

When selecting a new employee, Facebook looks for certain aspects. So, if you want to increase your chances of being hired, make sure you display the following aspects during your coding interview:

Able to Write Code on a Whiteboard

An important aspect that recruiters take into consideration is whiteboard coding. When you code on a whiteboard, you're likely to reveal any flaws in your coding. Recruiters are looking for candidates who don't strike off code repeatedly without thinking it through. It's critical to practice on a whiteboard when preparing for an on-site interview, as this is a common question asked.

Programming Language Proficiency 

Another key aspect is programming language proficiency. Facebook uses a range of languages, so you need to be proficient in at least one. You should be able to write code on more advanced algorithms, data structures, and problem-solving questions. Good programming language skills are critical in the phone screen and on-site interview.

Coding Style and Efficiency

In addition to proficiency, being able to code efficiently is another key aspect that will make you stand out. This includes how well you write code and how easily others can understand your code. It's important to be familiar with common coding style idioms and practices.

Ability to Articulate Solutions

When you're solving a problem, it's essential to explain your solution clearly. This includes being able to walk the interviewer through your code line by line. The ability to articulate solutions is key, as it shows that you understand the problem and are confident in your abilities.

Correcting Mistakes 

You can make mistakes, but it's how we handle them that counts. It's essential to be able to identify and correct mistakes quickly. This shows that you're able to debug code efficiently and effectively. You need to show that you can find and fix errors in your code.

These are some of the key aspects that Facebook looks for when hiring new employees. By displaying these qualities, you'll increase your chances of being hired.

Most Asked Facebook Interview Coding Questions

Now that you know what Facebook is looking for, it's essential to be familiar with the most asked coding questions. The following are the common questions asked in a Facebook coding interview:

  • Arrays

  • Linked Lists

  • Trees

  • Strings

  • Dynamic Programming

  • Math and Stats

  • Backtracking

  • Graphs

  • Design

  • Sorting and Searching


It is a data structure that stores a collection of elements. The elements are accessed by their index, which is the element's position in the array. The most common array questions asked in an interview are:

  1. Find the minimum and maximum elements in an array.

  2. Find the central element of an array.

  3. Given an array B[] and a number x, check for pair in B[] with sum as x.

  4. Reverse an array.

  5. Rotate an array by k positions

  6. Moving zeros to the left.

  7. Replace every element with the greatest element on its right side.

  8. Duplicates in an array.

  9. Merging overlapping intervals.

  10. Subarray with given sum.

Linked Lists

It is a data structure consisting of a series of nodes. Each node contains data and a reference to the next node in the list. The most common linked list questions asked in an interview are:

  1. Add two numbers represented by two linked lists.

  2. Delete the first occurrence of a number from a linked list.

  3. Implement a queue using a linked list.

  4. Check if two linked lists are equal.

  5. Add two integer numbers represented by two linked lists.

  6. Reverse a singly linked list.

  7. Remove duplicates from an unsorted linked list.

  8. Check if a given singly linked list is circular or not.

  9. Find the length of a loop in a linked list.

  10. Merge two sorted linked lists


It is a data structure consisting of nodes. Each node contains data and references the left and right child nodes. The most common trees questions asked in an interview are:

  1. Level traversal order of the binary tree.

  2. Find the least common ancestor of two nodes in a binary tree.

  3. Print all paths from the root to leaves in a binary tree.

  4. Given a binary tree, check if it is balanced or not.

  5. Delete a node from (BST) Binary Search Tree.

  6. Convert a binary tree to a doubly-linked list.

  7. Find the inorder successor of a given node.

  8. Diameter of a binary tree.


A string is a data structure that stores a sequence of characters. The most common string questions asked in an interview are:

  1. Check if it's an equal string or not.

  2. Find the length of a string.

  3. Extract substring from a given string.

  4. Convert all uppercase letters to lowercase in a string.

  5. Find the first occurrence of a given character in a string.

  6. Check if it is a palindrome string or not.

  7. String segmentation (finding all words in a string).

  8. Remove all duplicate characters from a given string.

  9. Print all permutations of a given string.

  10. Compress a given string using run-length encoding.

Dynamic Programming

It is a recursive problem-solving technique. The most common dynamic programming questions asked in an interview are:

  1. Matrix chain multiplication.

  2. Longest common subsequence.

  3. Knapsack problem.

  4. Shortest path in a graph.

  5. Breadth-first search and depth-first search algorithms for traversing a graph.

  6. Determine maximum single sell profit.

Math and Stats

Math and statistics are two crucial topics in coding interviews. The most common math and statistics questions asked in an interview are:

  1. Given a set of points, find the closest pair of points.

  2. Find the factorial of a number.

  3. Compute the nth Fibonacci number.

  4. Find the square root of a number.

  5. Counting permutations and combinations.

  6. Standard deviation.

  7. Variance.

  8. Given a number, compute its power.

  9. Logarithm.

  10. Integer division and remainder.


It is a technique for solving problems by building a solution incrementally. The most common backtracking questions asked in an interview are:

  1.  In a given string, find possible permutations

  2. Print all valid combinations of n-pairs of parentheses.

  3. Generate all possible subsets of a set.

  4. Find possible combinations of k numbers that add up to a given number.

  5. Make a directed graph from a source tree.


It is a data structure that consists of edges and nodes. The most common graph questions asked in an interview are:

  1. Determine a short path between two nodes in a graph.

  2. Find the minimum cost to reach from one node to another node in a graph.

  3. Check if a cycle is in a directed graph or not.

  4. Check if a given graph is bipartite or not.

  5. In an undirected graph, find the number of connected components. 

  6. Deserialize/ serialize binary tree.

  7. Topological sort of a directed graph.


Design questions are asked to assess a candidate's ability to design a system. The most common design questions asked in an interview are:

  1. How would you create a chat application?

  2. How would you develop a social network like Facebook?

  3. How would you create a file-sharing system like Dropbox?

  4. How would you create an online marketplace like Amazon?

  5. How would you design a web crawler?

  6. What are the trade-offs of different data structures?

  7. How to find the first unique character in a string?

  8. Implement an LRU cache.

  9. What is the difference between an interface and an abstract class?

  10. What is the difference between a HashMap and TreeMap?

Sorting and Searching

Sorting and searching are two essential topics in coding interviews. The most common sorting and searching questions asked in an interview are:

  1. Binary search.

  2. Merge sort.

  3. Quicksort.

  4. Heapsort.

  5. In an array, determine the kth smallest element.

  6. Find the kth largest element in an array.

  7. Search rotated array

  8. Find a given number's low and high index in a sorted array.

These are some of the most common Facebook coding interview questions. To prepare for your next interview, practice these questions and try to come up with solutions on your own.

How to Prepare for the Facebook Interview Coding Questions

Now that you know what to expect, here are some tips on how to prepare for the Facebook interview coding questions:

Practice a Variety of Problems

Practicing various problems is an excellent way to prepare. It will help you become familiar with the types of questions that are asked and the different ways to solve them. You can use several resources to find practice problems, such as online coding challenges and programming practice websites.

Don't Get Stuck on a Single Problem

If you find yourself struggling to solve a particular problem, don't spend too much time on it. It's important to move on and try other problems to avoid getting bogged down and running out of time. If you get stuck, take a break and return to the problem later.

Get Help from Others

If you're having trouble solving a problem, it can be helpful to ask others for help. There are online communities and forums where you can post questions and receive feedback from other programmers. You can also find coding interview question-and-answer pairs online.

Take Your Time

During the interview, it's essential to take your time and think through each problem before you start coding. It can help you avoid making mistakes and ensure that your code is correct. If you're not sure how to solve a problem, ask the interviewer for clarification.

Don't Be Afraid to Ask Questions

If you don't understand the question, don't be afraid to ask for clarification. The interviewer is there to help you, and they want you to do well. Asking questions shows that you're trying to understand the problem and take the time to think through your solution.

Stay Calm and Relaxed

It's crucial to stay calm and relaxed during the interview. If you're feeling stressed or anxious, take a few deep breaths and try to relax. Remember that the interviewer is there to help you, and they want you to do well.

These are some tips on how to prepare for Facebook coding interview questions. Follow these tips, and you'll be on your way to acing your next interview!

Ready to Ace Your Next Facebook Coding Interview?

If you want to advance your professional career, our top-rated recruiters at Recruitmently can help. They can help you understand Facebook coding interview questions, career advice, interview tips, and more. So, if you want to increase your chances of success in your next interview, sign up with Recruitmently today!

Do you have any questions about the Facebook coding interview questions? Let us know in the comments below!

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