Microsoft technical phone screen interview

Questions Microsoft asks in this round 39

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  ML fundamentals deep dive for ML rolesML designAfter a short walk through your resume, expect fast questions on machine learning basics, usually centred on your own area (language models, vision, recommendations). For each…

  Last asked Mar 2026Were you asked this too?
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  Top k largest elementsCodingGiven an integer array nums and an integer k, return the k largest elements of nums. You may return them in any order. The result is a multiset. If a value appears several times…

  Last asked Aug 2026Were you asked this too?
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  Build a hash map, make it thread-safe, and review a producer-consumer queueCodingImplement a hash map from scratch: hashing, buckets, collisions, resizing and the edge cases (null keys, rehashing while iterating). Then make it safe for many threads and discuss…

  Last asked Apr 2026Were you asked this too?
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  Design a RAG assistant with agentic toolsAI systemDesign an assistant that answers questions with retrieval-augmented generation and can call tools to act or fetch more information. Cover indexing, retrieval and re-ranking, when…

  Last asked Feb 2026Were you asked this too?
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  Top K frequent elementsCodingGiven an integer array and k, return the k values that occur most often, in any order; ties at the cutoff may go either way. One version asks for the most frequent request IDs in…

  Last asked Feb 2026Were you asked this too?
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  Temporal key-value store with point-in-time reads and restoreCodingBuild an in-memory key-value store that keeps every version of every key, so you can ask what a key held at any point in time. Implement the TemporalKVStore class: -…

  Last asked Jan 2026Were you asked this too?
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  Transformers and the challenges of deploying LLMsML designExplain how a Transformer works, then discuss recent advances in large language models, how you would apply one in the team's product, and the main problems with deploying LLMs in…

  Last asked Dec 2025Were you asked this too?
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  Most popular concert city from votes, with name variants and weightsCodingGiven vote records naming venue cities for a concert, return the most popular city. Follow-ups: the same city appears under many spellings (NYC, New York, new york city), so how…

  Possibly retiredWere you asked this too?
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  Three sum: unique value triplesCodingReturn every unique triple of values from an integer array that sums to zero (or to a given target), with no duplicate triples in the output. Sort, then fix one value and move two…

  Last asked Sep 2026Were you asked this too?
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  Validate a hierarchy and compute how long a message takes to spreadCodingGiven manager-report relationships, first check that they form a valid hierarchy (one root, no cycles, everyone reachable). Then, if passing a message down each link takes a known…

  Last asked Sep 2026Were you asked this too?
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  Parse a signed integer in any base, with overflow checksCodingWrite a production-quality parser that turns a string into a 32-bit signed integer in a given base. Handle signs, digits and letters valid for the base, and report invalid syntax…

  Last asked Aug 2026Were you asked this too?
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  Alien dictionaryCodingYou get a list of words sorted in the dictionary order of an unknown alphabet. Derive an order of the letters that is consistent with it, or report that none exists. Explain how…

  Last asked Aug 2026Were you asked this too?
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  Design an ad click aggregation systemSystem designCount ad clicks per ad and per time window from billions of events a day, accurately enough to bill advertisers, with results available within minutes.

  Last asked Aug 2026Were you asked this too?
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  Encode and decode TinyURLCodingImplement a class that turns a long URL into a short one and back, in memory. Discuss counter-based versus random or hash-based codes, collisions, the same long URL submitted…

  Last asked Jun 2026Were you asked this too?
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  Find the bugs in an AI-generated URL shortenerCodingYou are handed a URL shortener that an AI assistant wrote. Read it, find what is wrong (correctness, collisions, validation, concurrency) and fix it, explaining each problem. Only…

  Last asked Jun 2026Were you asked this too?
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  Design a to-do list service: CRUD, auth, rate limits, caching, versioningSystem designDesign the backend for a to-do list app: create, read, update and delete tasks, user authentication, rate limiting, caching, and versioning the API as it changes. Only the title…

  Last asked Jun 2026Were you asked this too?
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  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 May 2026Were you asked this too?
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  Basic calculatorCodingEvaluate an arithmetic expression string with non-negative integers, +, -, , / (integer division toward zero) and spaces, respecting operator precedence, without eval. State the…

  Last asked May 2026Were you asked this too?
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  Sort colors (three-way partition in place)CodingAn array holds only three kinds of values, such as 0, 1 and 2. Sort it in place in one pass without a counting sort. Explain the Dutch national flag partition and its invariants.

  Last asked Apr 2026Were you asked this too?
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  Implement team-style business logic with OOP, then roll out an API changeCodingThe interviewer describes logic similar to what the team builds and asks you to implement it with clean object-oriented design: classes, responsibilities and extension points…

  Last asked Apr 2026Were you asked this too?
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  Snapshot set with frozen insertion-order iteratorsCodingImplement SnapshotSet, a set of integers whose iterators are frozen at the moment they are created. - add(value) - bool: insert value. Return False and do nothing if it is already…

  Last asked Mar 2026Were you asked this too?
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  Design quality checks for spreadsheet data used to train an LLMML designYou are building training or evaluation data from spreadsheets for a language model. Design the checks that catch bad examples: structural problems, wrong or inconsistent values…

  Last asked Mar 2026Were you asked this too?
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  Design an AI chatbot appAI systemBuild a chatbot app on top of a hosted LLM API: conversations, streamed answers, history, and per-user usage limits.

  Last asked Mar 2026Were you asked this too?
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  Final discounted prices and the items sold at full priceCodingEach item in a list gets a discount equal to the price of the first later item that costs no more than it; items with no such later item sell at full price. Return the total paid…

  Last asked Mar 2026Were you asked this too?
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  Max points on a lineCodingGiven points on a plane, return the largest number of them that lie on one straight line. Explain how you represent slopes exactly (reduced fractions, not floats) and handle…

  Last asked Feb 2026Were you asked this too?
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  Closest latency pairs by minimum absolute differenceCodingA monitoring service records latency readings (whole milliseconds) and wants to flag readings that are suspiciously close to one another. Implement minabsdiffpairs(latencies:…

  Last asked Feb 2026Were you asked this too?
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  Design a logging serviceSystem designIngest logs from every service at terabytes per day, make them searchable within seconds, and keep them cheaply for months.

  Last asked Feb 2026Were you asked this too?
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  Precision and recall at k from a flaky top-k APICodingAn API returns a model's top-k predictions for each query, but calls sometimes fail or time out. Compute precision and recall against the true labels across a set of queries, with…

  Last asked Feb 2026Were you asked this too?
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  Choosing lock granularity for concurrent storageCodingFor a storage component used by many threads, compare one global lock, per-partition locks and per-object locks, plus reader-writer locks. Discuss throughput, deadlock risk and…

  Last asked Jan 2026Were you asked this too?
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  Design an S3-like object storage systemSystem designStore trillions of objects of any size with eleven nines of durability, and serve reads and writes over an HTTP API at high throughput.

  Last asked Jan 2026Were you asked this too?
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  Design live comments for a live streamSystem designViewers post comments on a live video and everyone watching sees them in near real time, including streams with huge audiences. Cover the write path, fan-out to viewers…

  Last asked Jan 2026Were you asked this too?
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  Group GPUs by node, then partition them by linksCodingGiven a list of GPUs with the node each sits on and the high-speed links between them, group the GPUs by node and then split each group into sets connected through links. Only the…

  Last asked Jan 2026Were you asked this too?
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  Owning and debugging infrastructure modulesBehavioralFor a storage or infrastructure role: describe a module you owned end to end, a hard production problem you debugged in it, how you found the root cause, and what you changed so…

  Last asked Jan 2026Were you asked this too?
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  Topological sort of a directed graphCodingReturn an order of a directed graph's nodes in which every edge goes from earlier to later, or report a cycle. Give Kahn's algorithm and the DFS version. Only the title of this…

  Last asked Jan 2026Were you asked this too?
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  Longest palindromic subsequenceCodingReturn the length of the longest subsequence of a string that reads the same forwards and backwards. Give the interval dynamic programming and its O(n^2) time.

  Last asked Dec 2025Were you asked this too?
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  Longest substring without repeating charactersCodingReturn the length of the longest substring with no repeated character, with a sliding window that remembers the last index of each character.

  Last asked Nov 2025Were you asked this too?
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  My calendar: book without double bookingCodingBuild a calendar whose book(start, end) accepts a half-open interval only if it does not overlap any existing booking. Compare a list scan with a sorted structure and binary…

  Last asked Nov 2025Were you asked this too?
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  Design tic-tac-toeOO designModel an N-by-N tic-tac-toe game for two players: moves, turn order, and detecting a win or draw efficiently after each move.

  Possibly retiredWere you asked this too?
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  Sum of the longest run of positive numbersCodingAn array holds positive and negative numbers. Find the longest contiguous run of positive numbers and return its sum (decide and state how ties between equally long runs are…

  Possibly retiredWere you asked this too?