AppleOnline Assessment

Company-style OA practice sets with full problem statements, sample test cases, and solutions.

4 Sets2 Questions/Set90 minLRU Cache & System Telemetry DesignTrie & Heap Top-K Frequent WordsNested Bracket String Parsing & StackTrapping Rain Water & Monotonic Height BoundsMatrix DFS & Longest Increasing Path

💰 Contribute & Earn

Have you recently taken Apple's Online Assessment or coding test? Share the questions, test cases, or assessment patterns you encountered. Earn SWE180 Coins for every verified submission and use them to unlock other company OA sets and premium tools for free!

Share OA & Earn Coins ➔

Practice Sets

Apple Coding Assessment Practice Set 1

90 min2 questions

Q1.

LRU Cache (App Switcher Memory Management)

Hash TableDoubly Linked ListDesign

Medium50 marks

Problem Statement

iOS background application management uses a Least Recently Used (LRU) cache policy to evict processes when RAM limits are reached.

Design a data structure that follows the constraints of a Least Recently Used (LRU) cache.

Implement the LRUCache class:

- LRUCache(int capacity) Initialize the LRU cache with positive size capacity.

- int get(int key) Return the value of the key if the key exists, otherwise return -1.

- void put(int key, int value) Update the value of the key if that key exists. Otherwise, add the key-value pair to the cache. If the number of keys exceeds the capacity from this operation, evict the least recently used key.

The functions get and put must each run in O(1) average time complexity.

Input Format

Sequence of LRUCache operations: get(k), put(k, v).

Output Format

Print the results of get calls.

Constraints

1 <= capacity <= 3000
0 <= key <= 10^4
0 <= value <= 10^5
At most 2 * 10^5 calls will be made to get and put.

Edge Cases

Capacity = 1
Updating an existing key (moves it to most recently used)

Sample Test Cases

Example 1

Input

LRUCache(2)
put(1, 1)
put(2, 2)
get(1)
put(3, 3)
get(2)
put(4, 4)
get(1)
get(3)
get(4)

Output

Explanation

put(1, 1) and put(2, 2) add items.

get(1) returns 1 and marks key 1 as most recently used.

put(3, 3) evicts key 2 (least recently used).

get(2) returns -1 (not found).

Candidate Instructions

Combine a Hash Map (for O(1) key lookups) with a Doubly Linked List with dummy head and tail (for O(1) node movement).

Time:O(1) for both get and put

Space:O(capacity)

Approach:Use a doubly linked list with head and tail sentinel nodes. A hash map maps keys to DLL nodes. On get(k): move node to head, return value. On put(k, v): if key exists, update value and move to head. If new, insert at head; if over capacity, remove tail.prev and delete from map.

Q2.

Top K Frequent Words (Siri Vocabulary Ranker)

TrieHeap (Priority Queue)SortingHash Table

Medium50 marks

Problem Statement

Given an array of strings words and an integer k, return the k most frequent strings.

Return the answer sorted by frequency from highest to lowest.

Sort the words with the same frequency by their lexicographical order.

Input Format

First line: two integers N and k.
Second line: N space-separated words.

Output Format

Print the top k frequent words separated by spaces.

Constraints

1 <= words.length <= 500
1 <= words[i].length <= 10
words[i] consists of lowercase English letters.
k is in the range [1, The number of unique words[i]]

Edge Cases

Multiple words with identical frequency (lexicographical sorting tie-breaker)

Sample Test Cases

Example 1

Input

6 2
i love leetcode i love coding

Output

i love

Explanation

"i" and "love" appear 2 times each. Since "i" comes before "love" lexicographically, "i" is placed first.

Candidate Instructions

Count frequencies with a map.
Use a Min-Heap of size k with comparator: smaller frequency first, and for equal frequency larger lexicographical string first.
Reverse heap output at the end.

Time:O(N log k)

Space:O(N)

Approach:Count frequencies. Use a Min-Heap of size k. The comparator compares frequency ASCENDING, and if frequencies match, word string DESCENDING. This ensures the smallest priority elements are popped first. Extract and reverse result.

Apple

AppleOnline Assessment

💰 Contribute & Earn

Practice Sets

Apple Coding Assessment Practice Set 1

LRU Cache (App Switcher Memory Management)

Problem Statement

Input Format

Output Format

Constraints

Edge Cases

Sample Test Cases

Candidate Instructions

Top K Frequent Words (Siri Vocabulary Ranker)

Problem Statement

Input Format

Output Format

Constraints

Edge Cases

Sample Test Cases

Candidate Instructions

Comprehensive Apple Online Assessment Patterns & Questions

Apple Exact Coding Questions

Test Patterns & Platforms

🔥 Why practice these assessments?