Citadel

Role: Senior Software Engineer (Citadel NXT)

College: Not Specified

Interview Date: Not Specified (experience posted recently, likely 2023-2024)

Interview Type: Full-Time

Result: Rejected

Difficulty: Hard

Rounds: 1 (First Round Technical Interview)

Topics Asked: Data Structures (Heaps, specifically max heap and min heap), Algorithms ("Find Median from Data Stream" problem)

Experience:

A Senior Software Engineer with 3 years of experience in backend and infrastructure development had their first round interview with Citadel for their NXT program.

The core technical question was to "Design a data structure" which essentially mirrored the classic LeetCode problem "Find Median from Data Stream." The candidate implemented the optimal approach using two heaps: a max heap for the lower half and a min heap for the upper half, ensuring balance and allowing O(log n) insertion and O(1) median retrieval.

The candidate felt the session went well, explaining their thought process clearly, writing working code, and optimizing properly.

Despite a seemingly strong performance, the candidate was rejected the next morning.