#python

36 python interview questions, asked at OpenAI, Apple, Meta and 15 more companies. Last asked Oct 2026.

Work queue with a dead-letter queue and dependency cycle detectionCodingBuild an in-memory work queue for pipeline tasks that depend on each other (download, then tokenize, then train). Workers call nextready() to take a task and report back with…
Last asked Oct 2026
Image transform pipeline with a wall-clock budgetCodingApply a fixed sequence of image transforms (grayscale, flip, scale, blur, rotate) to every image in a directory, then speed the batch up with threads or processes to hit a…
Last asked Oct 2026
+2
Memory allocator with malloc, free and coalescingCodingManage one arena of size bytes, addressed by offset from 0. You hand out and take back ranges of it, like malloc and free in C. Nothing is stored in the arena itself; track it in…
Last asked Oct 2026
+2
Crash-safe on-disk key-value storeCodingBuild a filesystem-backed hash table that survives crashes and restores every entry from the latest state on restart. Reported on 1point3acres' Baseten bank; reconstructed in our…
Last asked Sep 2026
+3
Deduplicate files by size then content hashCodingWalk a directory tree and group files with identical content. Compare file sizes first so large files are hashed only when sizes collide, then hash the rest. Be ready to discuss…
Last asked Sep 2026
Find the bugs in a dictionary memoization cache under concurrencyCodingA slow function is wrapped by a module-level dictionary that stores its results: look up the key, otherwise compute and store. You are shown the code and asked what breaks in…
Last asked Sep 2026
Single-pass cleaning pipeline for a million crawled web documentsCodingA take-home: input is a set of Parquet files with about a million documents crawled from public web pages. Write a Python pipeline that reads the input in a single pass and writes…
Last asked Sep 2026
Call a flaky HTTP API with Python requests and handle every errorCodingUsing Python's requests, write a client for a few endpoints of a fake API (you have its docs; the code does not need to run against a real server). Handle the failure cases…
Last asked Sep 2026
Median house price in each cityCodingGiven a list of house sales with a city and a price, return the median price for each city. Group the prices by city in a dictionary, sort each group, and take the middle value…
Last asked Sep 2026
Find super hosts from listing and review rulesCodingGiven host data with their listings, ratings and reviews, return the hosts who qualify as super hosts under several rules that must all hold, such as a minimum number of listings…
Last asked Sep 2026
Lazy tee iteratorCodingImplement tee in Python: from one source iterator, create n independent iterators that each yield the full sequence. Pull from the source only when some copy needs the next item…
Last asked Aug 2026
Indexed sequence with checkpointsCodingBuild a growable array that can take cheap snapshots. The spec arrives in three parts; finish and test each part before the next. Part 1. append(value) - index, pop() - value…
Last asked Jul 2026
Debug a Python job schedulerCodingYou own a small in-process job scheduler. It runs on a fake clock so it can be tested. Users report that: - a nightly report scheduled for exactly the end of a window sometimes…
Last asked Jul 2026
Clean a CSV of transactionsCodingWrite a small pipeline that reads a CSV file of transactions, validates and normalizes each row (types, formats, missing values), decides what to do with rows that cannot be…
Last asked May 2026
Data-parallel and fully sharded matrix multiply over simulated devicesCodingSimulated devices can only exchange tensors through send and receive calls. Finish a data-parallel matrix multiply, then implement a fully sharded version where each device holds…
Last asked Apr 2026
Find the bug in a loop conditionCodingYou are given a short Python program that does not behave as it should. Find the bug, which sits in a loop condition, explain why it causes the wrong behavior, and fix it.
Last asked Mar 2026
Flatten and rebuild nested Python containersCodingGiven an arbitrarily nested mix of lists, tuples and dicts with integer leaves, produce a flat list of the integers in order. Then, given the original structure and a new flat…
Last asked Mar 2026
Python fundamentals: a Fibonacci generator, a balanced BST and frozensetCodingA set of short Python tasks: write a generator that yields the Fibonacci sequence, build a balanced binary search tree (for example from a sorted list), and explain frozenset, how…
Last asked Feb 2026
Parallel chunked download with integrity checkCodingChange a sequential chunked file download to fetch chunks in parallel, then verify the reassembled file's integrity. Reported on 1point3acres' Baseten bank; reconstructed in our…
Last asked Feb 2026
Thread-safe task queue on a linked listCodingA task queue was written for one thread: a singly linked list with head and tail, where put appends at the tail and get removes from the head. Explain what goes wrong when many…
Last asked Feb 2026
Inheritance, polymorphism, constructors and destructorsCodingExplain the difference between inheritance and polymorphism, then write a short example in which a child class overrides a method of its parent. Next, compare constructors and…
Last asked Jan 2026
Build a text summarization API serviceCodingWith an AI assistant available, build a small production-style web service with FastAPI: POST /summarize takes JSON {"text": ...} and returns {"summary": ...}. Add input…
Last asked Jan 2026
Debug a project-assignment codebaseCodingYou get a small codebase spread over several files that assigns projects (for example to students or courses). Some tests fail. Read your way around it under time pressure, find…
Last asked Jan 2026
Load balancer with worker states, a priority queue and autoscalingCodingIn a time-boxed backend round, write a small load balancer in Python. Workers move through states (for example starting, idle, busy, draining), requests go to workers through a…
Last asked Dec 2025
Top three categories by total scoreCodingYou get a list of (category, score) tuples. Add up the score of each category and return the best total you can get from at most three categories (the three highest totals)…
Last asked Dec 2025
Most frequent key without max()CodingGiven a list of keys, return the one that appears most often without using the built-in max(). Count with a dictionary, track the best as you go, and decide how ties are broken.
Last asked Nov 2025
Python metaprogramming for features and resolversCodingThere is no written description, only test code: make the tests pass. You build a small framework in which classes declare features through type annotations and functions marked…
Last asked Sep 2025
Automatic emergency braking logic in PythonCodingWrite a simple automatic braking function in Python: given the vehicle's state and what is ahead of it (for example speed and distance to an obstacle), decide whether and how hard…
Last asked Sep 2025
Validate checkout and return logsCodingGiven a log of events per book, each a checkout or a return (a true/false flag), check that every book's events alternate correctly: a book must be checked out before it can be…
Last asked Sep 2025
Robust Python generator, then a weighted oneCoding1. Write a Python generator that yields the numbers of an input list, with unit tests. Handle edge cases such as None values and an empty list. 2. Change it to yield numbers from…
Last asked Sep 2025
Python practicals: debug async code, find files by pattern, read nested JSONCodingA set of short practical Python tasks: 1. Read a helper class that keeps pulling data from a response and writing it out, and explain what it is for. 2. Debug a piece of…
Last asked Aug 2025
Recommend accounts your followees followCodingGiven a dictionary from each user to the people they follow, for example {A: B, C, B: C, D, C: E}, return for a user every account followed by the people they follow that they…
Last asked Aug 2025
Python lists, dicts and concurrencyCodingAnswer Python fundamentals questions: how lists and dicts work underneath and the cost of their operations, then multithreading versus multiprocessing, the GIL, and when to use…
Last asked Jul 2025
Write a robust REST API methodCodingWrite one REST API method from end to end: validate the input, handle the request, return proper status codes and errors, and cover retries, timeouts and logging.
Last asked Jul 2025
Unique users per activity and average time on siteCodingEach record captures one user's action on a website, with the user, the activity and the time. Write code that returns the number of unique users for each activity and the average…
Last asked May 2025
Alert routing service with silences and escalationCodingBuild the routing core of an alerting service. The monitoring system calls fire(labels, now) for an active alert on every evaluation cycle (every 30 seconds or so) and…