Twitter / X

Twitter / X

Real-time social platform with petabyte-scale data and ML ranking systems.

4 Rounds ~14 Days Hard
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The Interview Loop

Recruiter Screen (30 min)

Standard fit check, behavioral questions, and resume overview.

Technical Loop (3-4 Rounds)

Deep dive into domain knowledge, coding, and system design.

Interview Question Bank

Backend Engineer • Coding • easy

Implement a function to parse a tweet string and extract all unique hashtags and user mentions, returning them in the order they appeared.

#String Manipulation #Regex #Hash Set
Practice
Backend Engineer • Coding • easy

Given a string containing a tweet, check if it is a palindrome, ignoring spaces, punctuation, and casing.

#String #Two Pointers
Practice
Backend Engineer • Coding • easy

Given two arrays representing the followers of User A and User B, write a function to return their mutual followers. Optimize for large arrays.

#Array #Hash Set #Two Pointers
Practice
Backend Engineer • Coding • medium

Write a function to detect if there is a cycle in a retweet chain (represented as a directed graph).

#Graph #DFS #Cycle Detection
Practice
Backend Engineer • Coding • medium

Given a list of tweets with timestamps, find the maximum number of tweets published within any 5-minute sliding window.

#Sliding Window #Two Pointers #Array
Practice
Backend Engineer • Coding • hard

Write an algorithm to serialize and deserialize a tree of threaded replies (N-ary tree) to a string and back.

#Tree #DFS #Serialization
Practice
Backend Engineer • Coding • medium

Given an array of intervals representing active ad campaigns, merge all overlapping intervals to find the total continuous time ads are running.

#Array #Sorting #Intervals
Practice
Backend Engineer • Coding • medium

Given a list of user connections (follower/following), write a function to find the shortest connection path between two users (Degrees of Separation).

#Graph #BFS #Bidirectional BFS
Practice
Backend Engineer • Coding • medium

Given a stream of tweets, write an algorithm to find the top K trending hashtags over the last 1 hour.

#Heap #Hash Map #Sliding Window
Practice
Cloud Engineer • Coding • medium

Given a list of server connection logs represented as [start_time, end_time], write a function to find the maximum number of concurrent connections and the time it occurred.

#Algorithms #Sweep Line #Sorting
Practice
Cloud Engineer • Coding • medium

Given a list of microservices and their dependencies (e.g., Service A depends on Service B), write an algorithm to determine a valid deployment order.

#Graphs #Topological Sort #Algorithms
Practice
Cloud Engineer • Coding • medium

Implement a rate limiter class in Python or Go using the Token Bucket algorithm. It should support multiple users identified by user_id.

#Python #Go #Rate Limiting #Concurrency
Practice
Data Engineer • Coding • easy

Given a list of trending search terms, group the anagrams together.

#Strings #Hash Maps
Practice
Data Engineer • Coding • medium

Implement an LRU Cache to store recently accessed user profiles.

#Linked Lists #Hash Maps #Caching
Practice
Data Engineer • Coding • medium

Implement a Trie data structure to support Twitter search autocomplete.

#Trees #Trie #String Manipulation
Practice
Data Engineer • Coding • medium

Parse a log file of Twitter events to find the top 10 most active users in a given 1-hour window.

#Log Parsing #Hash Maps #Sorting #Priority Queue
Practice
Data Engineer • Coding • medium

Implement a sliding window algorithm to count the number of tweets containing a specific hashtag in the last 5 minutes.

#Sliding Window #Queues #Real-time Processing
Practice
Data Engineer • Coding • hard

Given K sorted streams of tweet IDs (in chronological order), merge them into a single sorted stream.

#Heaps #Pointers #Stream Processing
Practice
Data Engineer • Coding • hard

Find the shortest path between two users in the Twitter follower graph.

#Graphs #BFS #Bidirectional Search
Practice
Data Engineer • Coding • medium

Implement a rate limiter for the Twitter API using a token bucket algorithm.

#Concurrency #System Design #Object-Oriented Design
Practice
Data Engineer • Coding • medium

Design an algorithm to find the Top K frequent words in a continuous stream of tweets (Heavy Hitters problem).

#Count-Min Sketch #Heaps #Streaming Algorithms
Practice
Data Scientist • Coding • medium

Given a dataset of user sessions, write a Python script to merge overlapping session time intervals.

#Sorting #Intervals #Arrays
Practice
Data Scientist • Coding • medium

Implement a basic TF-IDF algorithm from scratch in Python for a small corpus of tweets.

#NLP #Hash Maps #Math
Practice
Data Scientist • Coding • medium

Given an array of daily tweet counts for a specific hashtag, write a Python function to find the longest contiguous streak of days where the count strictly increased.

#Arrays #Dynamic Programming
Practice
Data Scientist • Coding • easy

Write a Python function to calculate the cosine similarity between two sparse user-feature vectors.

#Math #Arrays #Linear Algebra
Practice
Data Scientist • Coding • easy

Write a Python function to parse and extract all unique trending hashtags from a massive stream of tweet texts efficiently.

#Regex #Strings #Data Structures
Practice
DevOps Engineer • Coding • medium

Given a list of server logs with timestamps, write a program to find the peak traffic window of exactly 5 minutes.

#Sliding Window #Data Processing #Time Series
Practice
DevOps Engineer • Coding • hard

Implement a basic rate limiter in Python using a token bucket algorithm to protect our Tweet posting API from abuse.

#Python #Rate Limiting #Concurrency #Algorithms
Practice
DevOps Engineer • Coding • easy

Write a function to validate if a given string is a valid IPv4 or IPv6 address without using built-in IP validation libraries.

#String Manipulation #Networking #Validation
Practice
Full Stack Engineer • Coding • hard

Find the shortest path between two users on X (Degrees of Separation). You are given an API call `getFollowers(userId)`.

#Graph Traversal #BFS #Bidirectional BFS
Practice
Full Stack Engineer • Coding • hard

Given K sorted arrays representing timelines of users you follow, merge them into a single sorted timeline of the most recent tweets.

#Heaps #Merge Sort #Arrays
Practice
Full Stack Engineer • Coding • medium

Implement a rate limiter for the X API that allows a user to make N requests per time window T. How would you handle this in a distributed environment?

#Sliding Window #Concurrency #Distributed Systems
Practice
Full Stack Engineer • Coding • medium

Write a function to calculate the length of a Tweet. Note that URLs always count as 23 characters, and emojis/special Unicode characters should be counted correctly as single characters despite surrogate pairs.

#String Manipulation #Regex #Unicode
Practice
Full Stack Engineer • Coding • medium

Given a stream of tweets, write an algorithm to find the Top K frequent words (Trending Topics) in the last hour.

#Heaps #Hash Maps #Stream Processing
Practice
Full Stack Engineer • Coding • easy

Write a function to parse a raw tweet string and extract all valid hashtags, ignoring punctuation immediately following the tag.

#String Parsing #Regex
Practice
Machine Learning Engineer • Coding • easy

Design an algorithm to detect cycles in a directed graph (e.g., detecting retweet loops or bot rings).

#Graph Theory #DFS
Practice
Machine Learning Engineer • Coding • medium

Implement a Trie (Prefix Tree) to support insertion, search, and prefix search. This is used for hashtag autocomplete.

#Tries #Strings #Data Structures
Practice
Machine Learning Engineer • Coding • hard

Given a stream of tweets, write a function to keep track of the median engagement score in a sliding window.

#Heaps #Sliding Window #Stream Processing
Practice
Machine Learning Engineer • Coding • medium

Design a data structure that supports insert, delete, and getRandom in O(1) time.

#Hash Tables #Arrays #Design
Practice
Machine Learning Engineer • Coding • medium

Given a stream of tweets, write an algorithm to find the Top K trending hashtags in the last 1 hour.

#Heaps #Sliding Window #Stream Processing
Practice
Machine Learning Engineer • Coding • medium

Implement a rate limiter for the Twitter API.

#System Design #Concurrency #Data Structures
Practice
Machine Learning Engineer • Coding • medium

Given k sorted arrays of tweet timestamps, merge them into a single sorted array.

#Heaps #Divide and Conquer #Sorting
Practice
Machine Learning Engineer • Coding • medium

Find the shortest path between two users in a massive social graph (degrees of separation).

#Graph Theory #BFS #Bidirectional Search
Practice
Software Engineer • Coding • medium

Find the shortest path (degrees of separation) between two users in a massive directed graph of followers.

#Graph #BFS #Bidirectional Search
Practice
Software Engineer • Coding • hard

Given a stream of tweets, find the top K most frequent hashtags in the last 5 minutes.

#Sliding Window #Heap #Queue
Practice
Software Engineer • Coding • medium

Implement a Token Bucket rate limiter class with an `allow_request(user_id)` method.

#Concurrency #Math #Design
Practice
Software Engineer • Coding • hard

Given an array of k sorted arrays representing timelines from different users, merge them into a single sorted timeline.

#Heap #Divide and Conquer #Linked List
Practice
Software Engineer • Coding • medium

Design a simplified version of Twitter. Implement functions to post a tweet, get the 10 most recent tweets in a news feed, follow a user, and unfollow a user.

#Hash Table #Heap #Object-Oriented Design
Practice
Software Engineer • Coding • medium

Implement a thread-safe counter class for tracking tweet likes in a highly concurrent environment.

#Concurrency #Multithreading
Practice
Software Engineer • Coding • medium

Design an Autocomplete system for X handles. Implement `insert(handle)` and `search(prefix)`.

#Trie #String #Design
Practice
Software Engineer • Coding • hard

Write a function to parse a massive log file of API requests and return the 99th percentile latency.

#Math #Sorting #Bucket Sort
Practice
Software Engineer • Coding • easy

Given an array of tweet engagement scores (positive and negative integers), find the contiguous subarray with the maximum sum.

#Array #Dynamic Programming
Practice
Software Engineer • Coding • medium

Implement a sliding window algorithm to detect if a user has posted more than N tweets in the last M seconds.

#Queue #Sliding Window
Practice
Software Engineer • Coding • easy

Given a tree representing a tweet thread (replies to replies), write a function to find the maximum depth of the thread.

#Tree #DFS #BFS
Practice
Software Engineer • Coding • easy

You are given a list of user connections. Find the most influential user, defined as the user with the highest in-degree in the graph.

#Graph #Hash Table
Practice
Software Engineer • Coding • medium

Given a string, write a parser or state machine to extract all valid @mentions and #hashtags without using built-in regex libraries.

#String #State Machine
Practice
Software Engineer • Coding • easy

Given a string representing a tweet, calculate its length where URLs count as exactly 23 characters, regardless of their actual length.

#String #Parsing #Regex
Practice
Software Engineer • Coding • medium

Implement an LRU Cache to store the most recently accessed tweets.

#Hash Table #Doubly Linked List #Design
Practice

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