Citadel vs IBM Interview Questions
Citadel lists 101 LeetCode interview questions while IBM lists 115. They share 15 problems — 15% of Citadel's bank and 13% of IBM's. Focus on the overlap first, then drill into 86 Citadel-only and 100 IBM-only questions.
Overview
Preparation Strategy
Step 1 — Shared core: Solve the 15 overlapping problems first. These are the highest-yield questions for candidates interviewing at both Citadel and IBM.
Step 2 — Company-specific depth: Add Citadel-specific problems like Longest Non-decreasing Subarray From Two Arrays, Binary Tree Maximum Path Sum, Minimum Knight Moves and IBM-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
15 Shared Questions
High-priority problems to practice for both Citadel and IBM.
| Problem | Difficulty |
|---|---|
| LRU Cache | Medium |
| Merge Intervals | Medium |
| Best Time to Buy and Sell Stock | Easy |
| Find the Duplicate Number | Medium |
| Group Anagrams | Medium |
| Validate Binary Search Tree | Medium |
| Trapping Rain Water | Hard |
| N-Queens | Hard |
| Fizz Buzz | Easy |
| Climbing Stairs | Easy |
| Letter Combinations of a Phone Number | Medium |
| Median of Two Sorted Arrays | Hard |
| 3Sum | Medium |
| Longest Increasing Subsequence | Medium |
| Integer to Roman | Medium |
Unique to Citadel (86)
Problems in Citadel's list that do not appear at IBM.
Unique to IBM (100)
Problems in IBM's list that do not appear at Citadel.
Frequently Asked Questions
How many LeetCode questions do Citadel and IBM share?
Citadel and IBM share 15 LeetCode interview questions. 86 problems appear only in Citadel's list and 100 appear only in IBM's list.
What topics overlap most between Citadel and IBM?
The most common shared topics between Citadel and IBM are Array (9 shared questions), Hash Table (4 shared questions), Dynamic Programming (4 shared questions), String (4 shared questions), Sorting (3 shared questions). Mastering these areas prepares you for both companies.
Which company asks harder LeetCode questions: Citadel or IBM?
Citadel has 5 Easy, 60 Medium, and 36 Hard questions. IBM has 33 Easy, 73 Medium, and 9 Hard questions. Citadel has a higher proportion of Hard problems in its interview set.
How should I prepare if interviewing at both Citadel and IBM?
Start with the 15 shared problems since they cover what both companies ask most often. Then add 20 Citadel-specific and 20 IBM-specific questions to round out your prep.