This year, Apple Intern interviews have been sent out in large numbers, but I still noticed that some students didn’t even receive an OA. In my personal judgment, this is very likely a resume issue. As is widely known, each big tech company has different resume preferences—if you didn’t get picked up, the first thing to check is whether your projects align with the company’s style.
Apple Intern Interview Experience
OOD
We want to design a parking lot system using an object-oriented approach. This parking lot is not just a single level—it has multiple levels. Each level is further divided into rows of parking spots. The parking lot should be able to accommodate different types of vehicles, such as motorcycles, cars, and buses. The system should support two core functionalities: Being able to locate where a vehicle is parked (which level and which spot). Automatically calculating the parking fee when a vehicle leaves.
Approach: The parking lot system consists of the following core classes:
- Vehicle (base vehicle class): defines common vehicle attributes
- Motorcycle, Car, Bus (concrete vehicle classes): inherit from Vehicle
- ParkingSpot (parking spot): stores information about an individual parking spot
- Level (floor/level): manages the parking spots on each level
- ParkingGarage (parking lot): overall management of the entire parking facility
Code
Problem: Given a[0]…a[N-1], find i <= j such that a[i] = a[j], and the subarray sum a[i] + … + a[j] is maximized.
This problem may look like “finding two ends with the same value,” but the key idea is: when the right endpoint j is fixed, to maximize sum(i..j), we want prefix[i] to be as small as possible (since sum = prefix[j+1] − prefix[i]), and we must also have a[i] = a[j]. So I would do two things: first compute the prefix sums pref[k] = a[0] + … + a[k−1]; then for each value v, maintain “the minimum pref[i] seen so far among positions where the value is v (and the corresponding index i).”
When I scan to some j (with value v): I first use the current pref[j] to update the minimum prefix for v (this also covers the case i = j), then compute the candidate answer: pref[j+1] - minPref[v]. I update the global maximum and record i and j at the same time.
Solution
Data structure: HashMap(value -> (minPrefix, minIndex)) minPrefix: the minimum pref[i] achievable when this value is used as the left endpoint minIndex: the corresponding i, used to return the final interval.
Time complexity: O(N) (one pass through the array, with a HashMap operation at each step) Space complexity: O(U) (where U is the number of distinct values)
Follow-up 1: What if we require i < j (single-element subarrays are not allowed)?
It’s simple: when updating the answer, add a check that i < j; or change the timing of initializing/updating min_pref to “compute the candidate first, then put j into the map,” ensuring the left endpoint is always before the right endpoint.
Follow-up 2: What if we need to return “all intervals that achieve the maximum sum,” or apply a tie-break (e.g., if sums are equal, choose the shortest / earliest)?
Incorporate the tie-break rules into the update logic: If the sums are equal, compare the length (j − i); if still tied, choose the smaller i. If you need to return all intervals, you would need to keep multiple i’s in the map that share the same minimum pref value. (In most interviews, they won’t actually require returning all intervals—more often they’re testing how you define the tie-break.)
Coding + Fundamentals (CS Basics)
For Apple Intern interviews, in addition to coding, sometimes they test fundamentals + coding together. The fundamentals are mainly around operating systems, such as the volatile keyword in C, how virtual memory works, and the principles behind deadlocks.
Code: Implement a hash table that supports insertion, lookup, and deletion. This type of interviewer has a common trait: they like to micro-manage—for example, halfway through your implementation they may give you a hint and tell you not to do it one way but another (even though there’s often no real difference). We should go along with the interviewer; otherwise, they may start to “battle” you and view your approach through a confrontational lens. It’s human nature, but we want to avoid that hassle.
BQ：Out of your comfort zone, tight deadlines, unable to meet your commitment — how would you communicate with the customer?
Preparation Summary
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