Apple guide · Problem solving
Apple problem solving interview questions
44 questions, tiered for the Apple loop. Estimation, debugging, concurrency and trade-off questions that surface inside Apple coding and design rounds rather than as a round of their own: the "walk me through what happens" and "how big is this" prompts that separate levels.
Other Apple lists: Coding · System design
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must14 questions
Solve these cold. They cover the patterns this loop leans on hardest.
- Amortized Cost of a Dynamic Array
- Binary Search Off-by-One
- Bounded Blocking Queue
- Consistent Hashing Explained
- Estimate Daily Storage for Video Uploads
- Estimate Search Engine QPS
- Estimate Servers for an API Load
- Hash Table Worst Case and Mitigation
- Modifying a List While Iterating
- Pick the Data Structure for Each Scenario
- Quadratic String Building
- Thread-Safe Counter
- Token Bucket Rate Limiter Class
- What Happens When You Load a URL
should24 questions
Work through once, then revisit any you could not finish on paper.
- Break Down a Latency Budget
- Closure Late Binding in a Loop
- Convert DAU to Concurrent Users
- Dining Philosophers Deadlock
- Estimate CDN Bandwidth for a Live Event
- Estimate Email Storage for a Billion Users
- Estimate Log Volume per Day
- Estimate Memory for a URL Cache
- Floating-Point Equality
- Integer Overflow in Midpoint
- is vs ==
- LSM Tree vs B-Tree
- Mutable Default Argument
- Predict the Output - Generator Laziness
- Print in Order with Threads
- Process vs Thread vs Coroutine
- Read-Write Lock
- Recursion Depth Exceeded
- Recursion vs Iteration and Memory
- Shallow Copy of a Nested List
- TCP vs UDP: Choose for a Scenario
- Timezone-Naive Datetime
- Unstable Sort Assumption
- When n² Beats n log n
stretch6 questions
Only if the must and should lists feel easy. Commonly reported at senior levels or as follow-ups.
13 must-tier questions with full solutions
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Questions people ask
Are these the real Apple problem solving questions?
They are original questions built around the patterns commonly reported from Apple loops, not leaked or copied problems. Interviewers rotate questions constantly; preparing by pattern and tier is what transfers.
What do must / should / stretch mean?
Must: the patterns a Apple problem solving round leans on hardest; solve them cold. Should: work once and revisit. Stretch: senior-level or follow-up material.
What is free?
Every problem statement, examples and hints on this list. One problem solving question is fully open as a preview, and signing in unlocks the 13-question starter pack. The worked approach, solution, tests and per-company notes are in the guide.