#queue

11 queue interview questions, asked at Google, Amazon, Microsoft and 7 more companies. Last asked Oct 2026.

Per-user chat event counts in a sliding windowCodingA chat service runs for months without restarting. It sends you a stream of message events. Each event has a userid, a chatid and an integer timestamp in seconds. You must answer…
Last asked Oct 2026
+5
Sliding-window request rate limiterCodingImplement a rate limiter that accepts at most limit requests in any window of ttl milliseconds. - allow(timestamp) is called once per incoming request. timestamp is in…
Last asked Sep 2026
+2
Rate-limited event loggerCodingBuild a logger that rate-limits repeated events in a stream. Each event has a string name and an integer timestamp in seconds. Timestamps arrive in non-decreasing order, and…
Last asked Sep 2026
Rate limiter with multiple sliding-window rulesCodingBuild a rate limiter that enforces several rules at once. Each rule is a pair (limit, window): at most limit accepted requests may fall in any window of window time units. Use the…
Last asked Aug 2026
Process queue with wait limitsCodingA single server works through a line of n processes in first-in, first-out order. Process i (0-indexed, in line order) can wait at most waiti seconds. Once that much time has…
Queue with constant-time min and maxCodingImplement a FIFO queue of integers that can also report its smallest and largest element at any time. Implement the MinMaxQueue class: - MinMaxQueue() creates an empty queue. -…
Fuel station queue with three dispensersCodingA fuel station has three dispensers named X, Y and Z. Each starts with a known number of liters. A queue of cars waits at the station, and all of them are in line at time 0. Car i…
Two-player card game simulationCodingYou are building the engine for a simple two-player card game. Players are named "A" and "B". The deck is a list of distinct integers, and a higher integer beats a lower one…
Finish times for round-robin tasksCodingA single worker processes a list of tasks. Task i needs arri hours of work in total. The tasks wait in a queue in index order. Each turn, the worker takes the task at the front…
ATM queue exit orderCodingThere are n people waiting in a single line at an ATM. They are numbered 1 to n from the front of the line to the back. You are given an integer array amounts, where amountsi is…
Per-domain sliding-window rate limiterCodingA gateway receives requests one at a time, at most one per second. Each request names a domain. Build a rate limiter that keeps its state between calls and decides, for each…