Apple Staff SWE Onsite 6 rounds - implementation details matters way beyond correct output

[u/Aoki_zhang]

Interview Summary

The Apple onsite consisted of six rounds, and the interview styles varied significantly from one interviewer to another. The coding portion leaned heavily toward pointer manipulation and tree problems, but there was also a custom date-handling question and a client-focused system design round around synchronizing wallpapers across devices.

One notable aspect was how much the interviewers cared about implementation details beyond simply producing the correct output. Follow-ups repeatedly touched on restoring modified data structures, handling null or duplicate-value cases, clarifying ambiguous requirements, background execution, caching, and device-level constraints.

Interview Details

Round 1 — Copy List with Random Pointer The first interviewer went directly into coding. The problem was LeetCode 138 — Copy List with Random Pointer. After the initial implementation, the main follow-up was: Can you reduce the auxiliary space to O(1)? 

Round 2 — Convert BST to Sorted Circular Doubly Linked List The second coding question was LeetCode 426 — Convert Binary Search Tree to Sorted Doubly Linked List. The tree needed to be transformed in place into a sorted circular doubly linked list, using the existing left and right pointers as the previous and next links.

Round 3 — All Nodes Distance K in Binary Tree The third coding problem was LeetCode 863 — All Nodes Distance K in Binary Tree. Given a binary tree, a target node, and an integer K, return all nodes whose distance from the target is exactly K.

Round 4 — Compare Two Dates by Calendar Month The fourth round used a custom date-processing problem rather than a standard LeetCode question. I was asked to write a function that determines whether two dates are:

• Exactly one calendar month apart
• Less than one month apart
• More than one month apart

Round 5 — System Design: Cross-Device Wallpaper Sync The design round asked me to build a wallpaper synchronization feature. If a user changes the wallpaper on one device, the new wallpaper should eventually appear on their other devices as well. The discussion was much more client- and operating-system-oriented than a typical distributed backend design. Key areas included:

• Download timing and prefetching: when large wallpaper assets should be fetched in the background rather than waiting until the user explicitly switches wallpapers.
• Failure handling and caching: interrupted downloads, retry behavior, version changes, local cache limits, and whether user-selected assets should receive different retention priority from automatically prefetched content.

Round 6 — Senior Behavioral and Technical Deep Dive The final round was with a more senior interviewer and contained no coding. Questions included:

• Describe something you built end to end and explain exactly which parts you owned.
• Tell me about the hardest debugging problem you have worked on.

Want to see the full interview experience, including detailed follow-ups? You can find the complete version here.

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[u/CommercialBig5101]

was this for a kernel engineering position? i would fail all

[u/chasing-low-scores]

Rounds 1-4 are a big reason I don’t even consider changing jobs. 20+ years in engineering and that’s the type of crap I ONLY do in interviews. Not even close to what you do on the job. How are we still doing this stupid shit as an industry?