I recently completed a round of walking Apple SDE 面试，整体体验非常典型：不考八股、不聊过往项目、不问 system design，三轮全部纯 coding，但强度很高，下面分享 12 月这套真题。
Timeline
- 11.28 First round
- 12.12 Round 2 + Round 3 (completed on the same day)
The pace is not extremely fast, but the intensity of the last two rounds is quite high back to back, with almost no buffer time in between. The overall process was relatively straightforward and did not take long.
Round 1
The first question gives a system that continuously receives event log. Logs are incremented by timestamp, and each entry contains timestamp and eventType. The same eventType may appear many times in a short period of time. If all are stored as they are, a lot of memory will be wasted.
It is required to complete compressed storage during real-time append and support subsequent queries.
The key to this question is not statistics, but "how to do interval-level modeling of continuous repeated events." The natural idea is to compress consecutive identical eventTypes into a segment structure, and each segment records eventType, startTime, endTime and count.
When a new log arrives, if the type is the same as the current segment, the range is expanded; if it is different, a new segment is created. When querying, the time interval is divided into two parts to find overlapping segments for aggregation.
The interviewer will keep asking about insertion complexity, query complexity, what to do if timestamp no longer increments, and what to do if deletion is supported. The whole process tests whether your control of data structures is solid enough.
Round 2
The second question is a multi-version configuration system. The system has multiple configuration sources, each of which is a key-value map. Each update generates a new version number. It is now necessary to support querying the final effective value of a key under any historical version, and to configure a priority override relationship between sources.
The essence of this question is about persistent data structure. You cannot save a complete snapshot for each version, otherwise the space will explode. A reasonable approach is to only record changes in each update and reduce storage through version sharing.
When querying a key in a certain version, you need to look up the version chain for the latest modification to the key, and determine the final value based on priority rules.
The interviewer's questions focused on how to optimize query efficiency, how to avoid deep chain traversal, and what to do if the number of versions reaches millions. This round focuses more on engineering abstraction capabilities rather than pure algorithmic skills.
Round 3
The third question is a variation of topological sorting. Given a set of tasks, there are dependencies between them forming a DAG. At the same time, each task belongs to a certain group. Tasks in the same group must be executed serially in strict accordance with the order of submission. Different groups can be executed in parallel.
It is required to output a legal execution sequence, and try to start the task as early as possible under the legal premise.
The difficulty lies in how to translate the order constraints within the group into graph structure constraints. A common practice is to add implicit dependency edges for adjacent tasks in the same group, merge them with the original dependency edges, and then perform topological sorting in a unified manner.
The interviewer will ask whether a cycle is possible, what is the complexity, and what to do if the number of groups is large. The core of this question is not topological sorting itself, but whether the constraint modeling is rigorous.
Learn more
If you are preparing for technical interviews with Apple SDE or other major North American manufacturers, it is recommended not to just answer questions. We provide systematic interview coaching services, covering OA assistance,VO assists , 1v1 online real-time prompts and ideas provided by North American front-line CS engineers. Job hunting in North America is becoming more and more difficult. If you no longer want to work alone behind closed doors, please feel free to send me a private message to chat about your current progress and pain points, and we will see how we can help you break through.
