Citadel

The HackerRank questions they ask are very similar to their LeetCode tagged questions, but with some modifications. There was one number theory question. Make sure you have a basic understanding of modulo arithmetic.

It was a basic data structures question involving a heap. They asked to implement a stock broker type class to process buy and sell orders and match them if they're compatible.

Phone screen with HR. They ask you about your resume, past project experience, impact, and scope. They will then ask about your interests and intentions. You will also discuss compensation expectations.