Unlock the Top 20 Coding Questions to Pass Meta Interview

Imagine yourself working on products like Facebook, Instagram, and WhatsApp that connect billions of people every day. Sounds exciting, right?

But, getting through Meta’s interview process is not that simple like any top tech company—you need to properly prepare and practice.

If you’re wondering where to start, you’ve come to the right place!

In this blog, we’ll walk you through the top 20 coding questions that can help you succeed in your Meta interview. We’ll also give you an overview of the interview format and what Meta looks for in their candidates. So, let’s get started!

Section 1: Understanding Meta’s Interview Process

Meta, originally known as Facebook, was founded by Mark Zuckerberg in 2004 while he was a student at Harvard University. It started as a social network for college students but quickly grew to include users from around the world.

Over time, Meta expanded its services by acquiring other popular platforms like Instagram and WhatsApp.

In 2021, the company changed its name to Meta to reflect its focus on building the metaverse, a virtual reality space where people can interact.

Today, Meta is a major player in the tech industry, connecting billions of people globally.

Meta Interview Format

The interview process at Meta usually includes several stages:

• Initial Phone Screen: A recruiter will call you to discuss your background, experience, and interest in the role.

• Technical Screen: This includes one or two interviews focused on coding challenges. These can be conducted over the phone or through a video call.

• On-Site or Virtual Interviews: These consist of multiple rounds of interviews, including coding challenges, system design questions, and behavioral questions.

Find everything about Meta’s interview in 2024.

What Meta Looks For

Meta seeks candidates who are strong in these areas:

• Technical Skills: Proficiency in coding, algorithms, and data structures is crucial.

• Problem-Solving Ability: They want to see how you approach and solve complex problems.

• Collaboration: Good teamwork and communication skills are important. Meta values people who can work well with others.

• Culture Fit: Meta looks for individuals who are passionate, adaptable, and eager to learn and grow.

Learn more about Meta’s technical screening.

Types of Questions at Meta Interview

Meta interviews typically include:

• Coding Problems: These questions test your knowledge of data structures and algorithms. You might need to solve problems using arrays, trees, graphs, and more.

• System Design: These questions assess your ability to design complex systems. You’ll need to explain how you would build and scale systems. Check out the complete roadmap for system design interview at Meta.

• Behavioral Questions: These questions focus on your past experiences and how you handle different work situations. They help the interviewer understand how you work in a team and deal with challenges.

Section 2: 20 Coding Problems To Pass Meta Interview

Here are the top 20 coding problems you need to practice to clear the Meta interview:

1. Toeplitz Matrix

Problem Statement: Given an m x n matrix, determine if a given matrix is a Toeplitz matrix.

A Toeplitz matrix is one in which every diagonal from top-left to bottom-right has the same elements.

In other words, the matrix should have the property that each element is equal to the element diagonally down to its right.

Example:

• Input: [[1,2,3],[4,1,2],[5,4,1]]
• Expected Output: true
• Justification: All diagonals have the same elements. Diagonals of the above matrix are [5], [4, 4], [1, 1, 1], [2, 2], and [3].

Difficulty Level: Easy

Solution: Toeplitz Matrix

2. Remove All Adjacent Duplicates In String

Problem Statement: Given a string S, remove all adjacent duplicate characters recursively to generate the resultant string.

Example:

• Input: s = "abccba"
• Expected Output: “”
• Justification: First, we remove "cc" to get "abba". Then, we remove "bb" to get "aa". Finally, we remove "aa" to get an empty string.

Difficulty Level: Easy

Solution: Remove All Adjacent Duplicates In String

3. Minimum Depth of a Binary Tree

Problem Statement: Find the minimum depth of a binary tree. The minimum depth is the number of nodes along the shortest path from the root node to the nearest leaf node.

Example:

Difficulty Level: Easy

Solution: Minimum Depth of a Binary Tree

4. Tree Diameter

Problem Statement: Given a binary tree, find the length of its diameter. The diameter of a tree is the number of nodes on the longest path between any two leaf nodes. The diameter of a tree may or may not pass through the root.

Note: You can always assume that there are at least two leaf nodes in the given tree.

Example:

• Expected Output: 5
  • Justification: The diameter of the tree is: [4,2,1,3,6]

Difficulty Level: Easy

Solution: Tree Diameter

5. Island Perimeter

Problem Statement: You are given a 2D matrix containing only 1s (land) and 0s (water).

An island is a connected set of 1s (land) and is surrounded by either an edge or 0s (water). Each cell is considered connected to other cells horizontally or vertically (not diagonally).

There are no lakes on the island, so the water inside the island is not connected to the water around it. A cell is a square with a side length of 1. The given matrix has only one island, write a function to find the perimeter of that island.

Example:

• Input: matrix=

• Expected Output: 14
• Justification: The boundary of the island constitutes 14 sides.

Difficulty Level: Easy

Solution: Island Perimeter

6. Move Zeroes

Problem Statement: Given an array of integers nums, move all the 0s, which are present in the array to the end while maintaining the relative order of the non-zero elements.

Note: This rearrangement should be done in-place without using extra space for another array.

Example:

• Input: [1, 0, 2, 0, 3, 0, 4]
• Expected Output: [1, 2, 3, 4, 0, 0, 0]
• Justification: Here, all non-zero elements (1, 2, 3, 4) retain their order, and all zeros are moved to the end of the array.

Difficulty Level: Easy

Solution: Move Zeroes

7. Missing Ranges

Problem Statement: You are given two integers, lower and upper, specifying the inclusive range, and the sorted array of unique integers nums, where each element is in between [lower, upper].

We can say the number n is missing if n is not in the nums and falls in the range [lower, upper].

Return the shortest sorted list of ranges that covers all missing numbers. These ranges should fall within the inclusive bounds specified by the lower and upper limit integers.

Example:

• Input: nums = [0, 1, 3, 50, 75], lower = 0, upper = 99
• Expected Output: [[2, 2], [4, 49], [51, 74], [76, 99]]
• Justification: The missing ranges are 2, 4-49, 51-74, and 76-99. Each missing range is represented as a pair in the list, where both numbers are the same for a single missing number.

Difficulty Level: Easy

Solution: Missing Ranges

8. Rank Transform of an Array

Problem Statement: Given an array arr containing integers, replace each element with its rank in the array.

• The rank is determined based on the size of the element compared to others in the array.
• Smaller numbers get a lower rank, and equal numbers share the same rank.
• The ranking starts from 1.

Example:

• Input: [10, 20, 20, 30]
• Expected Output: [1,2,2,3]
• Justification: 10 is the smallest, so its rank is 1. 20, occurring twice, shares the rank 2. 30, being the largest, gets the rank 3.

Difficulty Level: Easy

Solution: Rank Transform of an Array

9. Palindrome Permutation

Problem Statement: Given a string s, return true if any permutation of the given string s can form a palindromic string. Otherwise, return false.

A palindrome is a word, phrase, number, or other sequences of characters that reads the same forward and backward (ignoring spaces, punctuation, and capitalization).

Example:

• Input: "tactcoa"
• Expected Output: true
• Justification: The string can be rearranged to form "tacocat", which is a palindrome.

Difficulty Level: Easy

Solution: Palindrome Permutation

10. Diagonal Traverse

Problem Statement: Given a 2D matrix of size m x n, return a 1D array containing elements of the matrix in the diagonal order.

Example:

• Input: matrix = [[1,2,3], [4,5,6]]
• Expected Output: [1,2,4,5,3,6]
• Justification: Traversal begins at 1, moves to 2, diagonally down to 4, up to 5, down to 3, and finally to 6.

Difficulty Level: Medium

Solution: Diagonal Traverse

11. Maximum Swap

Problem Statement: Given a non-negative integer num, return the maximum number, which you can create by swapping any two digits of the number only once.

If no swaps can improve the number, return the original number.

Example:

• Input: 2736
• Expected Output: 7236
• Justification: Swapping the first and second digits (2 and 7) results in the largest possible number.

Difficulty Level: Medium

Solution: Maximum Swap

12. Custom Sort String

Problem Statement: You are given two strings pattern and text. It is given that all characters of the pattern string are unique.

Rearrange the characters of the text string based on the characters' order in pattern string.

In other words, if a character a occurs before a character b in the pattern string, then a should occur before b in the output string.

Characters in text that do not appear in pattern should be appended at the end of the rearranged string in their original order.

Example:

• Input: pattern = "xy", text = "yyzx"
• Expected Output: "xyyz"
• Justification: In 'pattern', the order is 'x', 'y'. In the text, 'x' appears once, 'y' twice, and 'z' doesn't appear. So, we put z at the end of the string. Thus, the output string is xzyy.

Difficulty Level: Medium

Solution: Custom Sort String

13. Buildings With an Ocean View

Problem Statement: You are given an array heights of size n, representing the heights of n buildings.

The ocean is to the right of these buildings. A building has an ocean view if there are no taller buildings to its right. The task is to find the indices(0-based) of all such buildings with an ocean view.

Example:

• Input: [4, 3, 2, 1]
• Expected Output: [0, 1, 2, 3]
• Justification: Each building is shorter than the one to its left, hence all have an ocean view.

Difficulty Level: Medium

Solution: Buildings With an Ocean View

14. Basic Calculator II

Problem Statement: Given a string s, representing the mathematical expression, evaluate the expression and return the integer value.

The integer division should truncate toward zero.

Note: You are not allowed to use the built-in functions like eval().

Example:

• Input: "8*5/4+3-2"
• Expected Output: 11
• Justification: The calculation proceeds as follows: 8*5 = 40, 40/4 = 10, 10+3 = 13, 13-2 = 11.

Difficulty Level: Medium

Solution: Basic Calculator II

15. Dot Product of Two Sparse Vectors

Problem Statement: Given two sparse vectors, efficiently compute the dot product of them.

A sparse vector is one in which most elements are zero.

Implement class Solution:

• Solution(nums) Initializes the object with the vector nums
• dotProduct(vec) Calculates the dot product between the vec and instance of Solution.

Example:

• Input: vec1 = [1, 0, 0, 2], vec2 = [2, 3, 0, 1]
• Expected Output: 4
• Justification: The dot product is (12) + (03) + (00) + (21) = 2 + 0 + 0 + 2 = 4.

Difficulty Level: Medium

Solution: Dot Product of Two Sparse Vectors

16. Alien Dictionary

Problem Statement: There is a dictionary containing words from an alien language for which we don’t know the ordering of the letters.

Write a method to find the correct order of the letters in the alien language. It is given that the input is a valid dictionary and there exists an ordering among its letters.

Example:

• Input: Words: ["ba", "bc", "ac", "cab"]
• Expected Output: bac
• Justification: Given that the words are sorted lexicographically by the rules of the alien language, so from the given words we can conclude the following ordering among its characters:

1. From "ba" and "bc", we can conclude that 'a' comes before 'c'.

2. From "bc" and "ac", we can conclude that 'b' comes before 'a' From the above two points, we can conclude that the correct character order is: "bac"

Difficulty Level: Hard

Solution: Alien Dictionary

17. Best Meeting Point

Problem Statement: You are given m x n matrix containing 1 and 0 digits only, where each 1 represents the home of one friend, return the minimum total travel distance.

The minimal total travel distance is defined as a sum of distances between each friend's house and meeting point. Here, you need to find the meeting point such that it should have minimal distance from the home of each friend.

The distance is calculated as the Manhattan distance, which is the sum of the absolute differences in the horizontal and vertical coordinates (distance(a1, a2) = |a2.x - a1.x| + |a2.y - a1.y|).

Example:

• Input: [[1,0],[0,1]]
• Expected Output: 2
• Justification: There are two people located at the top-left and bottom-right corners. The best meeting point is either of the two empty cells, each resulting in a total distance of 2.

Difficulty Level: Hard

Solution: Best Meeting Point

18. Making A Large Island

Problem Statement: Given a 2D binary matrix of size n x n, return the integer representing the size of the largest island after changing at most 0 to 1. Here, Island is defined as a 4-directionally connected group of 1s.

Example:

• Input: [[1, 0, 1, 0],[0, 1, 1, 0],[0, 0, 0, 1],[1, 1, 0, 0]]
• Expected Output: 6
• Justification: Converting the water cell at position (2,1) will connect two large islands (top right and bottom left) with a new land cell, creating an island of size 6.

Difficulty Level: Hard

Solution: Making a Large Island

19. Longest Increasing Path in a Matrix

Problem Statement: Given a 2D matrix of size m x n, return the length of the longest increasing path in the matrix. The increasing path should have each element should be greater than the previous element in the path.

It is given that you can move only in 4-directions: left, right, top, and bottom.

Example:

• Input: matrix =[[3, 4, 5], [3, 2, 6], [2, 2, 1]]
• Expected Output: 4

• Justification: The longest increasing path is 3 -> 4 -> 5 -> 6. No other path has a greater length.

Difficulty Level: Hard

Solution: Longest Increasing Path in a Matrix

20. Serialize and Deserialize Binary Tree

Problem Statement: Serialization involves converting a binary tree into a string format such that it can be stored in the file or memory, preserving its structure and data.

Deserialization, on the other hand, is about reconstructing the binary tree from this string representation.

Design an algorithm to serialize and deserialize the binary tree. There is no restriction on designing the algorithm for serialization and deserialization of the binary tree.

Example:

• Input: [1,2,3,null,null,4,5]

• Expected Output: [1,2,3,null,null,4,5]
• Justification: The tree starts with the root node 1, followed by its left child 2 and right child 3. Since 2 and 3 have no left children, they are followed by null. Nodes 4 and 5 are the left and right children of 3.

Difficulty Level: Hard

Solution: Serialize and Deserialize Binary Tree

Final Words

Meta looks for problem solvers, clear thinkers, and team players.

It's not just about knowing the right answers but also showing how you approach and solve problems. Show them you can tackle tough problems, write clean code, and work well with others.

The questions we’ve covered will give you a solid start, but don’t stop there—keep practicing and learning. Most importantly, stay calm and confident during your interview.