Apple vs Citadel Interview Questions
Apple lists 300 LeetCode interview questions while Citadel lists 101. They share 59 problems — 20% of Apple's bank and 58% of Citadel's. Focus on the overlap first, then drill into 241 Apple-only and 42 Citadel-only questions.
Overview
Preparation Strategy
Step 1 — Shared core: Solve the 59 overlapping problems first. These are the highest-yield questions for candidates interviewing at both Apple and Citadel.
Step 2 — Company-specific depth: Add Apple-specific problems like Two Sum, Design Hit Counter, Longest Common Prefix and Citadel-specific problems from the exclusive lists below.
Step 3 — Difficulty tuning: Citadel skews harder in our data. Budget extra time for Hard problems if you are targeting that company.
Difficulty Comparison
Top Shared Topics
59 Shared Questions
High-priority problems to practice for both Apple and Citadel.
| Problem | Difficulty |
|---|---|
| LRU Cache | Medium |
| Number of Islands | Medium |
| Merge Intervals | Medium |
| Best Time to Buy and Sell Stock | Easy |
| Group Anagrams | Medium |
| Course Schedule II | Medium |
| Course Schedule | Medium |
| Best Time to Buy and Sell Stock II | Medium |
| Merge k Sorted Lists | Hard |
| Trapping Rain Water | Hard |
| Median of Two Sorted Arrays | Hard |
| Design Circular Queue | Medium |
| Find Median from Data Stream | Hard |
| Insert Delete GetRandom O(1) | Medium |
| Climbing Stairs | Easy |
| Search a 2D Matrix II | Medium |
| 3Sum | Medium |
| Implement Trie (Prefix Tree) | Medium |
| Sqrt(x) | Easy |
| Max Points on a Line | Hard |
| Find Servers That Handled Most Number of Requests | Hard |
| Regular Expression Matching | Hard |
| Best Time to Buy and Sell Stock with Transaction Fee | Medium |
| Maximal Square | Medium |
| Serialize and Deserialize Binary Tree | Hard |
| Container With Most Water | Medium |
| Letter Combinations of a Phone Number | Medium |
| Sliding Window Maximum | Hard |
| Permutations | Medium |
| Fizz Buzz | Easy |
Showing top 30 of 59 shared problems.
Unique to Apple (241)
Problems in Apple's list that do not appear at Citadel.
| Problem | Difficulty |
|---|---|
| Two Sum | Easy |
| Design Hit Counter | Medium |
| Longest Common Prefix | Easy |
| Rotate Array | Medium |
| Reverse Linked List | Easy |
| Valid Sudoku | Medium |
| Top K Frequent Elements | Medium |
| Valid Parentheses | Easy |
| Longest Substring Without Repeating Characters | Medium |
| Product of Array Except Self | Medium |
| Valid Palindrome | Easy |
| Rotate Image | Medium |
Unique to Citadel (42)
Problems in Citadel's list that do not appear at Apple.
Frequently Asked Questions
How many LeetCode questions do Apple and Citadel share?
Apple and Citadel share 59 LeetCode interview questions. 241 problems appear only in Apple's list and 42 appear only in Citadel's list.
What topics overlap most between Apple and Citadel?
The most common shared topics between Apple and Citadel are Array (18 shared questions), Dynamic Programming (7 shared questions), Hash Table (6 shared questions), Design (6 shared questions), String (6 shared questions). Mastering these areas prepares you for both companies.
Which company asks harder LeetCode questions: Apple or Citadel?
Apple has 76 Easy, 178 Medium, and 46 Hard questions. Citadel has 5 Easy, 60 Medium, and 36 Hard questions. Citadel has a higher proportion of Hard problems in its interview set.
How should I prepare if interviewing at both Apple and Citadel?
Start with the 59 shared problems since they cover what both companies ask most often. Then add 20 Apple-specific and 20 Citadel-specific questions to round out your prep.