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187 questions in the library. A source association does not guarantee a future interview question.
Behavioral and leadership · Coding · Machine learning · ML system design · Other questions · System design
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Finite state machines LinkedList Questions Behavioural
Companies: Apple
Last reported Jun 2026
Check whether a string becomes a palindrome after lowercasing and removing all non-alphanumeric characters. The typical challenge is to do this efficiently (O(n)) by scanning…
Companies: Apple, Bloomberg, Meta
String · Two Pointers
Last reported Jun 2026
Find the length of the longest contiguous substring that contains no repeated characters. This is a classic sliding-window / two-pointer problem where you track seen…
Companies: Apple, Amazon, Autodesk, Bloomberg +12
Hash Table · Sliding Window · String
Last reported May 2026
Given numCourses and prerequisite pairs, return any ordering of courses that satisfies all prerequisites or an empty array if impossible — this is essentially computing…
Companies: Apple, Amazon, Anduril, Citadel +11
Breadth-First Search · Depth-First Search · Graph Theory · Topological Sort
Last reported May 2026
Maintain an evolving rooted family tree (king as root) that supports adding a child and marking a person dead, and return the current inheritance order…
Companies: Apple, Snowflake
Depth-First Search · Design · Hash Table · Tree
Last reported May 2026
Design a logger system that receives messages with timestamps and only prints each message if it hasn't been printed in the last 10 seconds, with…
Companies: Apple, Amazon, Google, Microsoft
Last reported May 2026
Companies: Apple
Last reported May 2026
Design a system that ingests and processes logs from multiple services to extract useful insights, including the ability to track 5xx errors per service and…
Companies: Apple, Amazon, GitHub
Last reported Apr 2026
Check whether a string of parentheses/brackets is valid by ensuring every closing bracket matches the most recent unmatched opening bracket and the types and nesting…
Companies: Apple, Amazon, Bloomberg, Google +9
Bracket Sequences · Stack · String
Last reported Apr 2026
Design a full machine translation pipeline using Transformer-based models that allows users to translate text between languages, covering key stages including data collection…
Companies: Apple
Last reported Mar 2026
Design algorithms to serialize an N-ary tree into a single string and deserialize it back, preserving node values and the arbitrary number and order of…
Companies: Apple, Bloomberg, Rubrik, TikTok
Breadth-First Search · Depth-First Search · String · Tree
Last reported Mar 2026
Implement an LFU cache with O(1) average-time get and put operations that evicts the least-frequently-used key when capacity is exceeded, breaking ties by least-recently-used…
Companies: Apple, Amazon, Cisco, Goldman Sachs +3
Design · Doubly-Linked List · Hash Table · Linked List
Last reported Mar 2026
Given a flights graph and a matrix of vacation days per city per week, start at city 0 and choose each week whether to stay…
Companies: Apple, Datadog, Meta
Last reported Mar 2026
Check whether a given abbreviation (letters mixed with digits that denote how many characters to skip) correctly represents a target word. The core challenge is…
Companies: Apple, Meta
Last reported Mar 2026
Companies: Apple
System Design
Last reported Mar 2026
Check whether any substring of s2 of length |s1| is a permutation of s1 (i.e., has the same character multiset). The core challenge is to…
Companies: Apple, Meta
Hash Table · Sliding Window · String · Two Pointers
Last reported Mar 2026
Count word frequencies and return the k most frequent words sorted by descending frequency, breaking ties by lexicographical order. The core challenge is combining frequency…
Companies: Apple, Microsoft, Oracle, Robinhood
Array · Bucket Sort · Counting · Hash Table
Last reported Mar 2026
Design a high-availability, low-latency configuration management system that allows developers to commit configuration changes and have them propagate globally across multiple…
Companies: Apple
Last reported Mar 2026
Design a video calling application similar to Apple FaceTime that allows users to make one-on-one and group video calls with features like call management, contact…
Companies: Apple
Last reported Mar 2026
Write a function that reads a binary file containing a fixed-length header followed by data records. Parse the header to determine metadata such as the…
Companies: Apple
Last reported Mar 2026
Local-time recurrence, bounded free/busy queries, invitation state, and reminders that remain correct when schedules change.
Companies: Apple, Amazon, Google, LinkedIn +3
event-driven · idempotency · recurrence · scheduling
Last reported Feb 2026
Design and implement a thread-safe lottery system that supports adding/removing users with equal weights and selecting random winners. The system must handle concurrent…
Companies: Apple
Last reported Feb 2026
Companies: Apple
System Design
Last reported Feb 2026