OpenAI

OpenAI

Leading AI research laboratory developing state-of-the-art foundation models like GPT-4.

5 Rounds ~21 Days Very 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

Software Engineer • Coding • medium

Implement a rate limiter for the OpenAI API that restricts users based on both requests per minute (RPM) and tokens per minute (TPM).

#Data Structures #Concurrency #API Design
Practice
Software Engineer • Coding • medium

Write a function to perform a simplified Byte-Pair Encoding (BPE) tokenization on a given string, given a vocabulary of base characters and a list of merge rules.

#String Manipulation #Greedy Algorithms #Hash Maps
Practice
Software Engineer • Coding • hard

Implement a concurrent web crawler to fetch web pages for building an LLM training dataset. The crawler must respect robots.txt, handle domain-level rate limits, and avoid memory overflow.

#Concurrency #Graph Traversal #System Resources
Practice
Software Engineer • Coding • easy

Given a stream of API request logs containing user_id, timestamp, and token_count, write a function to calculate the monthly billing per user based on a tiered pricing model.

#Data Processing #Math #Hash Maps
Practice
Software Engineer • Coding • medium

Implement a text justification algorithm optimized for streaming chunks of text as they are generated by an LLM, ensuring the UI updates smoothly without jarring reflows.

#String Manipulation #Streaming Data #UI/UX considerations
Practice
Software Engineer • Coding • medium

Write an algorithm to efficiently merge multiple sorted streams of log data (timestamped events) from thousands of different GPU nodes into a single chronological stream.

#Heaps #Sorting #Distributed Data
Practice
Software Engineer • Coding • medium

Find the longest substring with at most K distinct characters. (Analogy: optimizing a context window for specific entity types).

#Sliding Window #Strings #Hash Maps
Practice
Software Engineer • Coding • hard

Implement a basic Byte-Pair Encoding (BPE) tokenizer from scratch given a corpus of text.

#Strings #Data Structures #NLP
Practice
Software Engineer • Coding • medium

Design a thread-safe rate limiter for the OpenAI API that can handle burst traffic and different tier limits (e.g., Free vs. Pro users).

#Concurrency #System Design #Data Structures
Practice
Software Engineer • Coding • medium

Write a Python async function to fetch data from multiple endpoints concurrently, with a strict timeout and exponential backoff retry logic.

#Python #Asyncio #Networking
Practice
Software Engineer • Coding • medium

Implement an LRU Cache with a Time-To-Live (TTL) feature. If an item is expired, it should not be returned.

#Data Structures #Caching
Practice
Software Engineer • Coding • medium

Merge K sorted arrays, representing log files from distributed training nodes, into a single sorted output.

#Heaps #Sorting #Distributed Systems
Practice
Software Engineer • Coding • medium

Implement a Trie data structure for fast prefix matching to filter out blocked or policy-violating prompt keywords.

#Trees #Strings #Safety
Practice
Software Engineer • Coding • hard

Implement a distributed task queue for scheduling model evaluation jobs across a cluster of workers.

#Distributed Systems #Concurrency #Queues
Practice
Software Engineer • Coding • hard

Write a C++ program to efficiently multiply two large matrices, optimizing for CPU cache locality.

#C++ #Performance Optimization #Computer Architecture
Practice
Software Engineer • Coding • medium

Given a string of text, write a function to reverse the order of words, but keep the punctuation in its original relative position.

#Strings #Two Pointers
Practice
Software Engineer • Coding • medium

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

#Data Structures #Hash Maps #Arrays
Practice
Software Engineer • Coding • hard

Given a directed acyclic graph (DAG) representing dependencies of training jobs, write a function to execute them in the correct order concurrently.

#Graphs #Topological Sort #Concurrency
Practice
Software Engineer • Coding • hard

Implement a simplified version of Byte Pair Encoding (BPE) tokenization from scratch given a vocabulary and a text string.

#String Manipulation #Greedy Algorithms #Data Structures
Practice
Software Engineer • Coding • medium

Design a thread-safe rate limiter using the Token Bucket algorithm to be used across a distributed API cluster.

#Concurrency #Distributed Systems #Data Structures
Practice
Software Engineer • Coding • hard

Write a streaming JSON parser that can handle incomplete JSON strings, similar to processing chunks generated sequentially by an LLM.

#Parsing #State Machines #String Manipulation
Practice
Software Engineer • Coding • medium

Given a list of API requests with start and end timestamps, find the maximum number of concurrent requests at any point in time.

#Arrays #Sorting #Sweep Line Algorithm
Practice
Software Engineer • Coding • medium

Write a function to perform matrix multiplication efficiently, then explain how you would optimize it for CPU cache locality.

#Math #Memory Management #Optimization
Practice
Software Engineer • Coding • hard

Implement a distributed task queue in Python using asyncio, supporting task priorities, retries with exponential backoff, and concurrency limits.

#Asynchronous Programming #Heaps #System Design
Practice
Software Engineer • Coding • medium

Find the shortest path in a Directed Acyclic Graph (DAG) representing a neural network computation graph to optimize memory allocation.

#Graphs #Topological Sort #Dynamic Programming
Practice
Software Engineer • Coding • hard

Implement a sliding window attention mechanism algorithm that computes attention scores only for the last K tokens.

#Sliding Window #Arrays #Math
Practice
Software Engineer • Coding • medium

Write an async Python script to fetch data from multiple endpoints, aggregate the results, and handle timeouts or partial failures gracefully.

#API Integration #Asynchronous Programming #Error Handling
Practice
Software Engineer • Coding • medium

Merge K sorted streams of training data efficiently, assuming the streams are too large to fit into memory.

#Heaps #External Sorting #Pointers
Practice
Software Engineer • Coding • hard

Implement a streaming JSON parser that yields valid JSON objects as chunks of characters arrive over a network.

#Parsing #State Machines #Streaming
Practice
Software Engineer • Coding • medium

Write an algorithm to find the longest common substring between two large text documents to detect potential training data memorization.

#Dynamic Programming #Suffix Trees #Rolling Hash
Practice
Software Engineer • Coding • medium

Write a script to efficiently sample from a probability distribution of logits given a specific temperature parameter.

#Math #Probability #Arrays
Practice
Software Engineer • Coding • medium

Implement a function that takes a string and a list of forbidden words, and redacts the forbidden words in O(N) time.

#Trie #Aho-Corasick #String Matching
Practice

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Senior Engineer

Focuses on core competencies, system constraints, and clear communication.

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