+1Reachability in a time-indexed train scheduleCodingGiven train departures and arrivals with timestamps, decide whether a destination is reachable from a start station without time travel. Reported on 1point3acres' Glean bank;…
Last asked Oct 2026
#scheduling
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- Document indexing queue assignmentCodingAssign incoming documents to indexing workers across queues so the load stays balanced as documents arrive. Reported on 1point3acres' Glean bank; reconstructed in our own words.Last asked Sep 2026
+5Design a GPU scheduling platformAI system designShare a large GPU cluster among research and production teams: queue training and inference jobs, enforce quotas and priorities, place jobs on topology-aware hardware, and preempt…Last asked Sep 2026- +1Design a video generation service on a scarce GPU poolAI system designUsers submit text-to-video requests that each need minutes of GPU time, and the GPU pool is limited and changes size. Design the request flow, scheduling and workers, how users…Last asked Sep 2026
Deployment windows in a recurring weekCodingDeployments are planned on a recurring week measured in minutes, from 0 to 10,079, and the same schedule repeats every week. Teams declare windows in which deployment is allowed…Last asked Sep 2026
Design a workflow orchestration systemSystem designUsers define a workflow as steps with dependencies, then start runs of it. Design the system that runs each step once its dependencies finish, records the state of every run and…Last asked Sep 2026- Hotel stay email schedule with booking changesCodingA hotel wants to send each guest a set of emails around their stay. Write the code that produces the full email schedule. Input - reservations: a list of objects with guestname…Last asked Sep 2026
- +3Design a CI/CD systemSystem designOn every commit, build and test the code on a fleet of workers, then roll it out to production safely, with logs, retries and rollbacks.Last asked Sep 2026
Customer support dispatcher for agents who take breaksCodingBuild the core of a dispatcher for a customer support team. Customers get in touch and wait. Human agents sign in, serve one request after another, and sometimes leave, even in…Last asked Sep 2026
+12Design a distributed job schedulerSystem designDesign a service that runs millions of scheduled and on-demand jobs (cron-like and one-off) reliably across a fleet of workers.Last asked Sep 2026
Schedule video processing across CPU and GPU workersSystem designVideo processing jobs have stages, some suited to CPUs and some to GPUs. Design how jobs are split into stages and scheduled across the two pools of machines to keep both busy…Last asked Aug 2026
+1Shift grants with promotions that start next entryCodingTrack workers clocking in and out, apply promotions starting from the next office entry, and total granted bonuses across overlapping work sessions. - Level 1: addworker(id…Last asked Aug 2026- Dependency-aware concurrent tool schedulerCodingBuild a scheduler that runs a set of tool calls concurrently while respecting their dependencies: a call starts only after every call it depends on has finished, and independent…Last asked Aug 2026
Design a reliable job schedulerSystem designDesign a service that runs jobs at scheduled times at large scale, such as payment jobs that must run on time and exactly once in effect. Cover storing schedules, finding jobs…Last asked Aug 2026- Schedule tasks with cooldownsCodingTasks of several types run one per time unit, and two tasks of the same type must be separated by a cooldown. Arrange the tasks so the rule holds and the total time (idle slots…Last asked Jul 2026
Remove a GPU node and reschedule its podsCodingGiven a cluster of GPU nodes running pods, drain one node and reschedule its pods onto the remaining nodes respecting their resource requirements. Reported on 1point3acres'…Last asked Jul 2026- Data labeling scheduler with prefix-balanced modelsCodingA data labeling platform pairs tasks, AI models and human annotators. IDs are 1-indexed strings: tasks "t1"…"t{totalTask}", models "m1"…"m{totalModel}", humans…Last asked Jul 2026
Design a control plane that tracks hosts and assigns jobsSystem designDesign a central service that knows the live state of many compute hosts and hands jobs to them. Focus on how hosts and the service talk (heartbeats, push versus pull), where…Last asked Jun 2026- +3Design Google CalendarSystem designCreate events, invite people, handle recurring events and time zones, show free/busy, and send reminders, for hundreds of millions of users.Last asked Jun 2026
- Thread-safe scheduler for periodic jobsCodingWrite a scheduler that runs functions periodically, at a frequency such as 50 Hz, with schedule and cancel. One thread runs the jobs while other threads may add or cancel them at…Last asked May 2026
Task scheduler that pops the earliest deadline once its subtasks are doneCodingImplement a class with addtasks(tasks) and consumetask(). Each task has an id, a deadline and a list of subtasks. 1. consumetask returns the task with the earliest deadline, or a…Last asked May 2026- Design calendar event conflict handlingSystem designIn a calendar service, design how conflicts between events are found and handled: overlapping events for the same person or room, two bookings made at the same moment, and…Last asked Apr 2026
Design re-engagement notifications for inactive usersSystem designDesign a system that brings back users who stopped using an AI assistant product: decide who to contact, when and over which channel, what to say, how often, and how to measure…Last asked Apr 2026
Design a price tracking serviceSystem designTrack the prices of millions of products across stores and alert users when a product they watch drops below their target price.Last asked Mar 2026
+1Single-threaded scheduler for one-shot, delayed and periodic tasksCodingBuild a scheduler that runs on a single thread and accepts three kinds of jobs: run once now, run once after a delay, and run every N units of time. Decide how the clock moves…Last asked Feb 2026- Design a job scheduler for ETL pipelinesSystem designDesign a system that runs ETL jobs on schedules and as dependency graphs: defining pipelines, triggering, distributing work to workers, retries, backfills, monitoring and avoiding…Last asked Feb 2026
- Free 30-minute time slotsCodingGiven the busy intervals in a day, return every available 30-minute slot.Last asked Jan 2026
Find all GPU idle timesCodingFrom GPU task schedules, compute every idle window where no task runs. Reported on 1point3acres' Fireworks AI bank; reconstructed in our own words.Last asked Jan 2026- Design a dependency-aware job schedulerSystem designDesign a job scheduler in which each job is a list of tasks with dependencies between them; a task may start only when every task it depends on has finished. Cover how you…Last asked Jan 2026
- Design Airbnb's notification systemSystem designSend booking confirmations, reminders and host messages over push, email and SMS, respecting user preferences and time zones, without duplicates.Last asked Dec 2025
- Account scheduler with locking and LRU selectionCodingBuild a scheduler that hands out accounts from a pool to callers. An account that is handed out is locked until it is released, and when several accounts are free the scheduler…Last asked Dec 2025
- Design a job schedulerSystem designDesign a service that runs jobs for other teams: jobs can run once, at a given time or on a recurring schedule. Cover how jobs are submitted and stored, how the scheduler finds…Last asked Sep 2025
- Allocate servers from a pool of mixed node typesCodingA pool holds servers of several node types. Requests ask for a number of servers of a given type; the allocator hands them out and takes them back on release. Design the class and…Last asked Sep 2025
Most tasks finished before their deadlinesCodingGiven tasks with durations and deadlines, run them one at a time and choose as many as possible so that each finishes by its deadline. Return how many. Sort by deadline and use a…Last asked Aug 2025- Delayed job schedulerOO designDesign and code a scheduler that accepts a job and a delay and runs the job after that many seconds. Cover the data structure that finds the next due job, the worker thread or…Last asked Aug 2025
- +1Minimum workers with first-free job assignmentCodingJobs arrive as (jobid, start, end) with half-open times start, end). Workers are numbered 0, 1, 2, ... Part 1. Process jobs by start time (ties by job id). Each job goes to the…
- Merge intervals for streaming GPU tasksCodingMerge overlapping time intervals for GPU tasks arriving as a stream. Reported on 1point3acres' Fireworks AI bank; reconstructed in our own words.
- Find eligible GPU nodes for a podCodingFilter a fleet of GPU nodes down to the ones that can host a pod with given CPU, memory and GPU requirements. Reported on 1point3acres' Together AI bank; reconstructed in our own…
- Maximum profit from unit-time tasks with deadlinesCodingYou are given a list of tasks. Each task is a list of three strings: name, deadline, profit. - Every task takes exactly 1 second, and only one task can run at a time. - Time…
- Gift delivery scheduler with limited agentsCodingYou are planning gift deliveries to employees in an office. The workday runs from hour 9 to hour 17. You get: - intervals, a list of start, end pairs with integer hours. Employee…
- Smallest free hub for a taskCodingYou run a fleet of n compute hubs, numbered 0 to n - 1, and need to place one new task on a single hub. You are given: - capacities: an integer list of length n. capacitiesi is…
- Take down servers in a reliability drill with minimum total requestsCodingA reliability drill shuts down a fleet of n servers. Server i handles requesti requests every second while it is up, and starts with healthi health. You are also given an integer…
- +1Find bottleneck dependencies in a parallel buildCodingYou are given n build targets numbered 0 to n - 1 and a list of directed edges edges. An edge u, v means target v cannot start building until target u has finished. The graph has…