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Practice coding, system design, behavioral, and project questions for frontier AI roles.
Every question has a public brief with the task, constraints, and follow-ups. Labels describe interactive practice access.
Reported interview periodNot available
A recruiter conversation that stays on one run you owned.
Practice focusRecruiter round, two minutes. One run you owned. Who it was for. The constraint. What you did with your own hands. The skill that transfers. One skill you would learn in the first month.
Reported interview periodNot available
Build a map whose values survive a process crash. A memory-only map does not meet the contract.
Practice focusget returns the stored value or nothing. put stores a pair and must reach disk before it returns. Startup reads the file and rebuilds the map. A torn or partial final line is ignored. Requirements - Part one is an append-only log. Each put adds one line. Startup replays the file. Never rewrite a line in place. - An update of an existing key appends a newer line. Replay keeps the last complete line for that key. - A second process that opens the same path must see committed values. - Part two is compaction.…
Reported interview periodNot available
Store sequences of integers so a shared beginning occupies one path. A plain trie uses one node per integer. Here, a run of nodes that each have only one child is stored as one edge.
Practice focusRequirements - Insert shares an edge when two sequences start the same way. A sequence with nothing in common gets its own branch. - Inserting a shorter sequence after a longer one must cut the long edge. - To cut an edge, walk until the new sequence disagrees. The shared head stays on the parent edge. The old tail becomes one child. The new tail becomes another. - A disagreement on the first integer splits that edge into a one-integer head plus two children. - Exact membership is true only for a sequence that was inserted, not for a proper head of one.…
Reported interview periodNot available
Sketch a pipeline that turns a script into shots, frames, audio, and a cut. Name which agent owns each stage. The hard part is consistency: characters, places, and props must hold across many scenes. Pacing is …
Practice focusRequirements - Use a scene record, character sheets, and a continuity tracker as shared memory. - Split the work into a director that turns a script into a shot list, a continuity agent that keeps a vector per character and prop, a renderer that calls a video model conditioned on both, and an editor that reviews cuts and pace. - Inside one clip, rely on the video model to keep a subject that leaves and re-enters the frame. Do not rebuild that part.…
Reported interview periodNot available
Compute the product of two matrices on a group of devices, two ways, and compare both results with a product computed on one device.
Practice focusRequirements - The device count divides both dimensions. One device is the local product. - Data-parallel: each device multiplies its row slice of the left matrix by the full right matrix and sends that block to rank zero, which stacks the rows. - Sharded: the left matrix is split by rows and the right matrix by columns. Over as many rounds as there are devices, each device passes its right-hand shard to the neighbor and adds that partial into the matching columns of the piece it keeps. - The communicator is a set of blocking queues.…
Reported interview periodNot available
Tell one story about a consequential decision you made with incomplete evidence. State what was known, what was unknown, the reversible step you chose, and the signal that would make you change course.
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
You own a useful model feature with a fixed launch date and one unresolved safety concern. Explain the concern, bound the plausible harm, choose what ships, and define the evidence required before expanding acc…
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
Design a service that runs repeatable evaluations for model versions and blocks promotion when a required suite regresses. Support immutable datasets, parallel workers, partial retries, audit history, and compa…
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
Tell one story about a disagreement with a product, research, policy, or operations partner. State the shared goal, the competing constraints, what you changed in your own position, and the decision the group m…
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
A team can improve model quality, reduce latency, or make failures easier to understand, but can fund only one this quarter. Choose a direction, state the users and evidence behind it, and define what would inv…
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
Design a platform where an AI assistant invokes approved tools on behalf of users. Include tool registration, argument validation, identity and consent, isolated execution, timeouts, idempotency, audit logs, an…
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
Explain why a high-ownership role fits you using one project where you found an unowned problem, chose a direction, and delivered a measurable result. State the boundary of your authority and when you asked for…
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
Design a gateway for low-latency model inference across several model versions and accelerator pools. Include admission control, routing, batching, deadlines, retries, overload behavior, observability, and safe…
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
Turn an unknown biased bit source into balanced choices, a sampled load estimate, and isolated concurrent batches.
Practice focusYou receive a hardware source raw bit() that independently returns 0 or 1 with one stable but unknown probability of returning 1 . The probability is strictly between zero and one, and no other random source is available. Implement the following four functions. Requirements 1. Extract balanced bits Read the raw source in fresh pairs. Discard pairs whose values match. For the first pair whose values differ, return its first value. A scripted source raises EOFError when exhausted; let that exception propagate, including for a partial pair.…
Reported interview periodNot available
Given a nondecreasing array and a target value, report where the target first appears, or -1 when it is missing. A logarithmic search is expected, even though the same value may occur many times.
Practice focusRequirements - Line one is the element count n . Line two holds the n space-separated integers in nondecreasing order, and is empty when n is 0. Line three is the target. - Return the smallest zero-based index holding the target, as a decimal string with no padding. - Return -1 when the array is empty or the target never appears. - Repeated values are expected, so an ordinary equality hit is not enough; after a match keep searching to the left while remembering the best index seen. - Keep the running time logarithmic in n .…
Reported interview periodNot available
A single thread records start and end events for nested function calls. For each function id, work out how many time units it actually spent running, excluding the units spent inside calls it made.
Practice focusRequirements - Line one is the number of functions; ids run from 0 to count - 1 and every id appears at least once. Line two is the number of event lines. - Each remaining line is <id :<start|end :<timestamp with integer fields. Events are chronological and properly nested on one thread. - An end timestamp is inclusive: the unit at that timestamp belongs to the call that is ending, so it contributes timestamp - previous + 1 units. - When a call begins on top of a running call, credit the units since the previous boundary to the caller.…
Reported interview periodNot available
Each house on a street holds a known amount of money, and robbing two neighboring houses on the same night trips the alarm. Choose houses with no two adjacent to collect the largest possible total.
Practice focusRequirements - Line one is the house count. Line two lists that many non-negative integer amounts, separated by spaces. - Adjacency is positional, so choosing the house at index i rules out only i - 1 and i + 1 . - Return the best total as a decimal string with no separators. - A single house contributes its own amount, and a zero amount is a legal choice, so a street of zeros answers 0 . - Every house is a candidate; skipping a house is never required just because it is small. - run case passes case["stdin"] to solve .…
Reported interview periodNot available
Two Python-style lists arrive as literal assignments. Collect every value that belongs to the first list but not the second, keeping the first list's order.
Practice focusRequirements - The input holds two assignment statements, one per entry: list1 = [...] followed by list2 = [...] . Both lists contain integers and may be empty. - The statements may be separated by a real newline or by a literal two-character \n escape; split on either form. - Return the kept values in their original list1 order. - Membership in list2 is decided by value, not by count or position, so a single occurrence there removes every matching occurrence in list1 .…
Reported interview periodNot available
Given a string, measure the longest contiguous stretch in which no character repeats. Report only the length of that stretch.
Practice focusRequirements - The input is a single string, and the trailing newline is not part of the payload. - A stretch must be contiguous, and every character inside it must be distinct. - Return the length as a decimal string, not the slice itself and not its starting position. - Characters compare exactly, so an uppercase and a lowercase letter are different characters. - A string whose characters all match answers 1 , and the longest stretch may sit anywhere in the payload.…
Reported interview periodNot available
Given a list of half-open time ranges, report the largest number of ranges that are active at the same instant.
Practice focusRequirements - Line 1 holds the number of bookings. Each following line holds start end , two integers with start strictly less than end . - Treat a booking as occupying the half-open interval [start, end) . - Because the interval is half-open, a booking that ends at a time does not conflict with one that starts at that same time. - Return the peak number of concurrent bookings as a decimal string. - An empty booking list returns "0" . - run case(case: dict) forwards case["stdin"] to solve .…
Reported interview periodNot available
Combine three nondecreasing integer lists into one nondecreasing list in which every distinct value appears once, then print it as a single space-separated line.
Practice focusRequirements - The input has exactly three lines. Each line starts with a count k followed by k nondecreasing integers. - The merged result must stay sorted and must contain each distinct value exactly once. - Values may be negative, zero, or positive. Duplicates can appear within one line and across lines. - Print the distinct values in one line separated by single spaces, with no leading or trailing space. - If all three lists are empty, return an empty string. - run case(case: dict) forwards case["stdin"] to solve .…
Reported interview periodNot available
Rearrange an integer list into the next larger lexicographic arrangement, wrapping around to the smallest arrangement when no larger one exists.
Practice focusRequirements - Line 1 holds the length n . Line 2 holds n integers separated by spaces. - Compare arrangements position by position from the left. The next arrangement is the smallest arrangement strictly greater than the current one. - Duplicate values are allowed. - If the current arrangement is already the largest, return the smallest arrangement, with values in ascending order. - Print the resulting list in one space-separated line, keeping the same length and the same multiset of values. - run case(case: dict) forwards case["stdin"] to solve .…
Reported interview periodNot available
Given a nondecreasing integer sequence, report how many different values it contains.
Practice focusRequirements - The input is one line of space-separated integers in nondecreasing order. - Equal values are therefore adjacent, and the sequence may contain negative values. - Return the number of distinct values as a decimal string. - You do not need to print or return the compacted sequence itself. - run case(case: dict) forwards case["stdin"] to solve . - Do not append a trailing newline to the returned string; return the value exactly once.
Reported interview periodNot available
Given a matrix, set every cell in a row or column that contains a zero to zero, deciding which rows and columns to clear from the original values rather than from the partially rewritten matrix.
Practice focusRequirements - Line 1 is rows cols . The next rows lines each hold cols integers. - For every cell that is 0 in the original matrix, its entire row and entire column become 0 . - Decide all affected rows and columns before writing any zeros, so zeros created by the update must not widen the cleared area. - Return the matrix with rows in their original order, values separated by single spaces and rows separated by newlines, with no extra text. - A matrix with no zeros is returned unchanged. - run case(case: dict) forwards case["stdin"] to solve .…