
Securing a role at Meta, a leader in technological innovation, often involves navigating a rigorous technical interview process. A cornerstone of this process is the assessment of your problem-solving abilities through coding challenges, typically presented in a style similar to those found on platforms like LeetCode. These questions are designed to evaluate not just your ability to write functional code, but also your understanding of data structures, algorithms, time and space complexity, and your approach to handling edge cases. Preparing effectively for these challenges is paramount, as they form a critical component of Meta's hiring decisions for engineering roles across various levels. Mastering these common patterns and problem types will significantly boost your confidence and performance in the actual interview, showcasing your technical proficiency and readiness for complex software development tasks at a global tech giant.
What Are Meta LeetCode Interview Questions?
Meta LeetCode interview questions are algorithmic and data structure-based problems used to assess a candidate's coding proficiency during technical interviews. They typically involve a well-defined problem statement requiring an efficient solution implemented in code. These questions cover a broad spectrum of computer science fundamentals, including arrays, strings, linked lists, trees, graphs, dynamic programming, sorting, searching, and more. The objective is not merely to arrive at a correct answer but also to demonstrate the thought process, ability to optimize, handle constraints, and communicate technical ideas clearly. Interviewers look for clean code, robust logic, and an understanding of why a particular approach is chosen over others, often discussing trade-offs in terms of performance and memory usage.
Why Do Interviewers Ask Meta LeetCode Interview Questions?
Interviewers at Meta ask LeetCode-style questions for several key reasons, all centered on evaluating a candidate's core engineering competencies. Firstly, they gauge problem-solving skills; these questions are essentially mini-puzzles that require logical thinking and algorithmic design. Secondly, they assess coding proficiency, ensuring candidates can translate their ideas into well-structured, bug-free, and readable code within a time limit. Thirdly, these questions reveal a candidate's understanding of data structures and algorithms, which are fundamental tools for building efficient and scalable software systems. They also help evaluate how a candidate handles constraints, edge cases, and optimizes solutions for time and space complexity. Ultimately, these questions serve as a standardized way to compare candidates' technical aptitude and predict their success in a demanding engineering environment like Meta.
Preview List
How do you determine if a given matrix is a Toeplitz matrix?
How do you remove all adjacent duplicates in a string?
How do you find the minimum number of operations to make a parentheses string valid?
How do you move all zeroes to the left in an array while maintaining the order of other elements?
How do you find the first duplicate in an unsorted array?
How do you find the maximum number of consecutive ones in a binary array?
How do you validate whether a given string is a valid IP address?
How do you reverse a singly linked list?
How do you clone a linked list with a random pointer?
How do you find the longest common prefix among a list of strings?
How do you find the minimum window substring that contains all characters of another string?
How do you check if two strings are anagrams of each other?
How do you find the first missing positive integer in an array?
How do you find the maximum area of water that can be trapped between two lines?
How do you determine if you can reach the end of an array by jumping?
How do you match a string with a wildcard pattern?
How do you convert a Roman numeral to an integer?
How do you find the missing number in a sequence of numbers?
How do you search for a target in a rotated sorted array?
How do you find the number of subarrays where the sum equals a given value?
How do you find the maximum depth of a binary tree?
How do you determine the maximum amount of money that can be robbed from a sequence of houses?
How do you find a single number in an array where every element appears twice except one?
How do you find two numbers in an array that add up to a given target?
How do you find the minimum number of columns that need to be deleted to make a binary matrix column-wise sorted?
How do you set the row and column of a matrix to zero if an element is zero?
How do you find the median of two sorted arrays?
How do you find the top K frequent elements in an array?
How do you find the square root of a number without using built-in functions?
How do you find the maximum amount of rainwater that can be trapped between bars?
1. How do you determine if a given matrix is a Toeplitz matrix?
Why you might get asked this:
This question tests your ability to traverse matrices, identify patterns, and handle array indexing carefully, common in data processing scenarios.
How to answer:
Iterate through the matrix, checking if each element matrix[r][c]
is equal to its top-left diagonal neighbor matrix[r-1][c-1]
.
Example answer:
2. How do you remove all adjacent duplicates in a string?
Why you might get asked this:
Evaluates stack usage for string manipulation, recursion, or iterative approaches for pattern removal, fundamental in string processing.
How to answer:
Use a stack (or a list acting as a stack) to build the result. If the current character matches the stack's top, pop; otherwise, push.
Example answer:
3. How do you find the minimum number of operations to make a parentheses string valid?
Why you might get asked this:
Checks your understanding of stack data structures and logic for validating and balancing sequences, essential for parsing expressions.
How to answer:
Iterate through the string, using a counter or stack. Increment for '(' and decrement for ')'. Count unmatched parentheses.
Example answer:
4. How do you move all zeroes to the left in an array while maintaining the order of other elements?
Why you might get asked this:
Assesses in-place array manipulation, two-pointer techniques, and efficient element rearrangement, crucial for memory optimization.
How to answer:
Use two pointers. One pointer iterates from the right (end), placing non-zero elements. The other fills leading zeros.
Example answer:
5. How do you find the first duplicate in an unsorted array?
Why you might get asked this:
Tests your ability to detect repetitions efficiently, often using hash sets or modifying the array in-place without extra space.
How to answer:
Use a hash set to store encountered numbers. If a number is already in the set, it's the first duplicate.
Example answer:
6. How do you find the maximum number of consecutive ones in a binary array?
Why you might get asked this:
A simple problem to check basic loop iteration, variable tracking, and conditional logic, a good warm-up or easy problem.
How to answer:
Iterate through the array, maintaining a current count of ones. Reset if a zero is encountered and update a max count.
Example answer:
7. How do you validate whether a given string is a valid IP address?
Why you might get asked this:
Assesses string parsing, validation logic, and handling of multiple string formats (IPv4/IPv6), common in network programming.
How to answer:
Split the string by '.' or ':' and validate each segment based on IPv4 or IPv6 rules (numeric range, hex characters, length).
Example answer:
8. How do you reverse a singly linked list?
Why you might get asked this:
A classic linked list problem testing pointer manipulation, iterative vs. recursive thinking, and handling null/edge cases.
How to answer:
Iteratively, keep track of prev
, curr
, and next_node
. Move curr.next
to prev
, then advance all pointers.
Example answer:
9. How do you clone a linked list with a random pointer?
Why you might get asked this:
Tests your understanding of linked lists with additional constraints, hash map usage for mapping original to cloned nodes, and multi-pass algorithms.
How to answer:
First, create copies of all nodes and map original nodes to their copies using a hash map. Then, assign next
and random
pointers.
Example answer:
10. How do you find the longest common prefix among a list of strings?
Why you might get asked this:
Examines string manipulation, character-by-character comparison, and edge case handling with empty or single-string inputs.
How to answer:
Take the first string as the initial prefix. Then, for each subsequent string, shorten the prefix until it matches.
Example answer:
11. How do you find the minimum window substring that contains all characters of another string?
Why you might get asked this:
A challenging problem testing sliding window technique, hash maps for character counts, and efficient window expansion/contraction.
How to answer:
Use a sliding window and two hash maps: one for target string character counts, one for current window counts. Expand right, shrink left.
Example answer:
12. How do you check if two strings are anagrams of each other?
Why you might get asked this:
A common string problem that evaluates hash map usage or sorting for character frequency comparison.
How to answer:
Count character frequencies for both strings using hash maps or arrays. If counts match for all characters, they are anagrams.
Example answer:
13. How do you find the first missing positive integer in an array?
Why you might get asked this:
A challenging array problem that requires clever in-place modification or understanding of cyclic sort to achieve O(N) time and O(1) space.
How to answer:
Place numbers i
at index i-1
. Iterate: if nums[i] != i+1
, swap nums[i]
with nums[nums[i]-1]
until correct. Then find the first mismatch.
Example answer:
14. How do you find the maximum area of water that can be trapped between two lines?
Why you might get asked this:
Tests the two-pointer technique and optimization for finding optimal pairs, a classic for geometric and array problems.
How to answer:
Use two pointers, one at each end. Move the pointer pointing to the shorter line inward. Calculate area at each step.
Example answer:
15. How do you determine if you can reach the end of an array by jumping?
Why you might get asked this:
Evaluates greedy algorithms or dynamic programming, demonstrating your ability to find reachable states or paths.
How to answer:
Work backward from the end. Keep track of the 'good' index (farthest reachable point). If it reaches index 0, return true.
Example answer:
16. How do you match a string with a wildcard pattern?
Why you might get asked this:
A complex string matching problem that often involves dynamic programming or recursive backtracking, testing pattern recognition.
How to answer:
Use dynamic programming where dp[i][j]
indicates if s[:i]
matches p[:j]
. Handle '*' and '?' rules carefully.
Example answer:
17. How do you convert a Roman numeral to an integer?
Why you might get asked this:
Tests string parsing, hash map usage for symbol values, and specific rule handling (e.g., IV = 4, not 6).
How to answer:
Define a dictionary for Roman symbols. Iterate through the string, if current value is less than next, subtract it; otherwise, add it.
Example answer:
18. How do you find the missing number in a sequence of numbers?
Why you might get asked this:
A basic array problem that checks understanding of mathematical properties (summation) or bit manipulation (XOR) for efficient solutions.
How to answer:
Calculate the expected sum of numbers from 0 to N. Subtract the sum of given numbers. The difference is the missing one.
Example answer:
19. How do you search for a target in a rotated sorted array?
Why you might get asked this:
A classic binary search variant that tests your ability to adapt standard algorithms to modified data structures and handle pivot points.
How to answer:
Use a modified binary search. Determine which half is sorted and whether the target lies within that sorted range.
Example answer:
20. How do you find the number of subarrays where the sum equals a given value?
Why you might get asked this:
Tests prefix sums and hash map usage for efficient counting of subarray sums, crucial for many array-based problems.
How to answer:
Use a hash map to store prefix sums and their frequencies. Iterate, calculate current prefix sum, check if (current_sum - k)
exists in map.
Example answer:
21. How do you find the maximum depth of a binary tree?
Why you might get asked this:
A fundamental tree traversal problem (DFS or BFS) that checks understanding of recursion, stack/queue usage, and tree properties.
How to answer:
Recursively, the max depth is 1 + the max depth of its left or right child. Base case: depth of a null node is 0.
Example answer:
22. How do you determine the maximum amount of money that can be robbed from a sequence of houses?
Why you might get asked this:
A classic dynamic programming problem that requires identifying optimal substructures and overlapping subproblems.
How to answer:
Use DP. For each house i
, decide to either rob it (add its value + dp[i-2]
) or skip it (dp[i-1]
). Choose the maximum.
Example answer:
23. How do you find a single number in an array where every element appears twice except one?
Why you might get asked this:
Tests knowledge of bit manipulation (XOR property) for efficient solutions, demonstrating understanding beyond simple hash sets.
How to answer:
Use the XOR bitwise operation. XORing a number with itself results in 0. XORing all numbers in the array will leave the unique number.
Example answer:
24. How do you find two numbers in an array that add up to a given target?
Why you might get asked this:
A fundamental problem assessing hash map usage for efficient lookups or two-pointer technique on sorted arrays.
How to answer:
Use a hash map to store numbers encountered and their indices. For each number, check if target - current_num
exists in the map.
Example answer:
25. How do you find the minimum number of columns that need to be deleted to make a binary matrix column-wise sorted?
Why you might get asked this:
Tests matrix traversal and comparison logic, requiring you to iterate through columns and check sorting order.
How to answer:
Iterate through columns. For each column, iterate rows to check if grid[r][c] > grid[r+1][c]
. If so, increment deletion count for that column.
Example answer:
26. How do you set the row and column of a matrix to zero if an element is zero?
Why you might get asked this:
A classic matrix manipulation problem that requires careful in-place modification or extra space to track zero positions.
How to answer:
Use first row/column as markers to track which rows/cols need to be zeroed. Handle the first row/column's own zero state separately.
Example answer:
27. How do you find the median of two sorted arrays?
Why you might get asked this:
A hard problem requiring understanding of binary search on partitions, array merging concepts, and handling even/odd total lengths.
How to answer:
Perform a binary search on the smaller array's partition to find the perfect split point such that elements left of partitions are correctly ordered.
Example answer:
28. How do you find the top K frequent elements in an array?
Why you might get asked this:
Tests hash map usage for frequency counting and then sorting or min-heap (priority queue) for selecting top K elements efficiently.
How to answer:
Count frequencies using a hash map. Then use a min-heap of size K to store (frequency, number) pairs, or sort by frequency.
Example answer:
29. How do you find the square root of a number without using built-in functions?
Why you might get asked this:
A numerical problem often solved with binary search or Newton's method, testing algorithm design for mathematical computation.
How to answer:
Use binary search. Search for a number mid
between 0
and x
such that midmid <= x
and (mid+1)(mid+1) > x
.
Example answer:
30. How do you find the maximum amount of rainwater that can be trapped between bars?
Why you might get asked this:
A challenging array problem involving two pointers, dynamic programming, or stack to efficiently calculate trapped water, common in design scenarios.
How to answer:
Use two pointers, left
and right
. Maintain maxleft
and maxright
for heights. Move pointer with smaller max_height
inward and add trapped water.
Example answer:
Other Tips to Prepare for a Meta LeetCode Interview
Beyond solving individual problems, holistic preparation is crucial for Meta's LeetCode-style interviews. First, solidify your understanding of core data structures and algorithms. As renowned computer scientist Donald Knuth famously said, "Algorithms are the heart of computer science." Don't just memorize solutions; understand the underlying principles and trade-offs. Practice coding problems consistently, but also dedicate time to reviewing your solutions for optimality and edge cases. Consider using a tool like Verve AI Interview Copilot, which offers personalized feedback and helps refine your approach to common coding challenges.
Second, practice explaining your thought process clearly and concisely. Interviewers value strong communication skills as much as coding ability. Walk through your logic, discuss complexities, and justify your design choices. As Jeff Bezos advises, "Good communication is not about saying things well, it's about making sure your message is understood." Verve AI Interview Copilot can simulate interview scenarios, allowing you to practice articulating your solutions under pressure and receive immediate feedback on clarity and structure. Finally, simulate full interview experiences to build stamina and confidence. Utilize resources that mimic real-world Meta interviews, including behavioral questions, to ensure you're well-rounded. Explore Verve AI Interview Copilot at https://vervecopilot.com to enhance your preparation with AI-powered insights and mock interviews. This comprehensive approach, combining targeted practice with effective communication and modern AI tools like Verve AI Interview Copilot, will significantly improve your chances of success.
Frequently Asked Questions
Q1: How important are optimal solutions (time/space complexity) for Meta interviews?
A1: Optimality is very important. Interviewers expect you to identify and implement the most efficient solution, discussing its time and space complexity.
Q2: Should I focus on a specific programming language for Meta interviews?
A2: Meta accepts various languages (Python, Java, C++). Choose the one you're most proficient in to showcase your problem-solving effectively.
Q3: Are behavioral questions part of Meta's technical interviews?
A3: Yes, behavioral questions are integrated to assess your collaboration, leadership, and problem-solving approach in team settings.
Q4: How many LeetCode problems should I solve to be prepared for Meta?
A4: There's no fixed number, but focusing on around 150-200 common "medium" and "hard" problems across various topics is a good starting point.
Q5: What if I get stuck on a problem during the interview?
A5: It's okay to get stuck. Communicate your thought process, ask clarifying questions, and discuss potential approaches with your interviewer.