Meta System Design Interview Questions
Practice 1,159 real Meta interview questions for 2026. Covers top categories — Coding & Algorithms, Analytics & Experimentation, Data Manipulation (SQL/Python), Behavioral & Leadership, and System Design — across Software Engineer, Data Scientist, Machine Learning Engineer, Data Engineer, and Product Manager roles. Real questions from actual interviews with detailed solutions. Expect a software-engineering-heavy loop: timed algorithmic coding (trees, arrays, graph/maze problems, delimiter/CSV parsing), system-design prompts like leaderboards, flight search and online-judge architectures, and an increasingly common AI-assisted coding round that mirrors real workflows. Data Scientist rounds emphasize product analytics and experimentation—designing tests, diagnosing spend drops and bots, evaluating unconnected content, and writing SQL for multi-account, seller, and vehicle metrics. Machine Learning Engineer questions skew toward recommender and ranking work (place and friend recommendation, sparse-matrix ops, linear-regression derivations, newsfeed dislike models). Data Engineers focus on data modeling, ETL, capacity calculations, reservations/utilization queries, and production SQL/Python tasks. For interview preparation, prioritize timed coding practice, system-design templates, rigorous SQL drills (joins/CTEs/aggregation), clear A/B-testing frameworks, and concise STAR behavioral stories tied to measurable impact.
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Compute SHOP spend share and model performance
You work on ads measurement. Advertisers can drive users to either Facebook Shop ('SHOP') or their own website ('WEBSITE'). After an ad is shown, you ...
Find the most-used app
You work on Oculus app engagement analytics. Tables user_activity - user_id (BIGINT) - date (DATE) — day of activity (assume UTC unless otherwise spec...
Define and estimate prevalence of unhealthy users
This question evaluates a data scientist's ability to operationalize an "unhealthy user" metric and compute its prevalence from session duration and d...
Implement sparse vector dot product
Question Design a SparseVector class for vectors of integers in which most entries are zero, and support an efficient dot product between two such vec...
Compute BST range sum
Given the root of a binary search tree and two integers low and high (inclusive), compute the sum of values of all nodes with low <= val <= high. Prov...
Solve windowed duplicates and target expression
1) Windowed duplicate check: Given an integer array nums and an integer k, determine whether there exist indices i and j such that nums[i] == nums[j] ...
Solve tree traversal and interval merging tasks
Part A — Column-wise Binary Tree Grouping: You are given the root of a binary tree. Group nodes by vertical column index, where the root has column 0,...
Remove runs of length at least k
Given a string s and an integer k (k >= 2), repeatedly remove every maximal contiguous group of the same character whose length is at least k, deletin...
Validate a simplified numeric string
Implement isValidNumber (s) that returns true if and only if the ASCII string s represents a valid number under these simplified rules: - Optional lea...
Solve matrix components, median, and traversals
1) Binary matrix component: Given an m x n grid of 0s (background) and 1s (objects), return the size of the largest connected component where connecti...
How would you measure shop-ads promotion success?
This question evaluates a data scientist's competency in metrics design, experimental evaluation, and causal inference for ads ranking systems, includ...
Sort a string by custom order
Sort a string by custom order Given a priority string P of distinct characters and a text string S, reorder S so that all characters appearing in P co...
Find power-of-two subarrays within sum range
Find power-of-two subarrays within sum range Given an integer array nums and an integer k, find all subarrays whose length is a power of two and whose...
Decide palindrome within k deletions
Decide palindrome within k deletions Given a string s and integer k, decide whether s can be transformed into a palindrome by deleting at most k chara...
Find buildings with rightward view
Find buildings with rightward view You are given an array of building heights aligned along a street that faces the ocean to the right. Return the ind...
Compute binary tree diameter
Compute binary tree diameter Given the root of a binary tree, compute the tree's diameter defined as the maximum number of edges on any path between t...
Recommend friends-of-friends
Question Given a dictionary such as {A:[B,C], B:[C,D], C:[E]}, return for a user U all people followed by U’s followees but not already followed by U....
Count uniques in sparse sorted array
Question A sorted array contains many duplicates but only a very small number of distinct values. Design an algorithm that counts how many unique numb...
Count active follow connections
Question Write SQL to return the current number of active follow connections. Events table columns: user_id, target_id, event_type ('request_follow', ...
Validate carpool capacity
Question LeetCode 1094. Car Pooling – Given trips[i] = [numPassengers, start, end] and an integer capacity, return true if the vehicle can fulfill all...