Citadel vs Oracle Interview Questions
Citadel lists 101 LeetCode interview questions while Oracle lists 314. They share 53 problems — 52% of Citadel's bank and 17% of Oracle's. Focus on the overlap first, then drill into 48 Citadel-only and 261 Oracle-only questions.
Overview
Preparation Strategy
Step 1 — Shared core: Solve the 53 overlapping problems first. These are the highest-yield questions for candidates interviewing at both Citadel and Oracle.
Step 2 — Company-specific depth: Add Citadel-specific problems like Longest Non-decreasing Subarray From Two Arrays, Delete and Earn, Count Palindromic Subsequences and Oracle-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
53 Shared Questions
High-priority problems to practice for both Citadel and Oracle.
| Problem | Difficulty |
|---|---|
| Binary Tree Maximum Path Sum | Hard |
| Minimum Knight Moves | Medium |
| Palindromic Substrings | Medium |
| Sliding Window Maximum | Hard |
| LFU Cache | Hard |
| LRU Cache | Medium |
| Merge Intervals | Medium |
| Best Time to Buy and Sell Stock | Easy |
| Find the Duplicate Number | Medium |
| Serialize and Deserialize Binary Tree | Hard |
| Insert Delete GetRandom O(1) | Medium |
| Evaluate Reverse Polish Notation | Medium |
| Number of Islands | Medium |
| Sudoku Solver | Hard |
| Find Median from Data Stream | Hard |
| Group Anagrams | Medium |
| Validate Binary Search Tree | Medium |
| Permutations | Medium |
| Merge k Sorted Lists | Hard |
| Binary Tree Zigzag Level Order Traversal | Medium |
| Search Suggestions System | Medium |
| Trapping Rain Water | Hard |
| N-Queens | Hard |
| Regular Expression Matching | Hard |
| Design Circular Queue | Medium |
| Combination Sum | Medium |
| Implement Trie (Prefix Tree) | Medium |
| Climbing Stairs | Easy |
| Letter Combinations of a Phone Number | Medium |
| Median of Two Sorted Arrays | Hard |
Showing top 30 of 53 shared problems.
Unique to Citadel (48)
Problems in Citadel's list that do not appear at Oracle.
Unique to Oracle (261)
Problems in Oracle's list that do not appear at Citadel.
| Problem | Difficulty |
|---|---|
| Longest Substring Without Repeating Characters | Medium |
| Two Sum | Easy |
| Top K Frequent Elements | Medium |
| Valid Parentheses | Easy |
| Meeting Rooms II | Medium |
| Longest Palindromic Substring | Medium |
| Spiral Matrix | Medium |
| Minimum One Bit Operations to Make Integers Zero | Hard |
| Search in Rotated Sorted Array | Medium |
| Remove All Adjacent Duplicates in String II | Medium |
| Reverse Linked List | Easy |
| Longest Consecutive Sequence | Medium |
Frequently Asked Questions
How many LeetCode questions do Citadel and Oracle share?
Citadel and Oracle share 53 LeetCode interview questions. 48 problems appear only in Citadel's list and 261 appear only in Oracle's list.
What topics overlap most between Citadel and Oracle?
The most common shared topics between Citadel and Oracle are Array (16 shared questions), String (7 shared questions), Hash Table (7 shared questions), Design (7 shared questions), Dynamic Programming (6 shared questions). Mastering these areas prepares you for both companies.
Which company asks harder LeetCode questions: Citadel or Oracle?
Citadel has 5 Easy, 60 Medium, and 36 Hard questions. Oracle has 61 Easy, 194 Medium, and 59 Hard questions. Citadel has a higher proportion of Hard problems in its interview set.
How should I prepare if interviewing at both Citadel and Oracle?
Start with the 53 shared problems since they cover what both companies ask most often. Then add 20 Citadel-specific and 20 Oracle-specific questions to round out your prep.