Did OA, initial round, and then 3x round.
3x round was 3 45-min interviews, each had some kind of different problem. Very interviewer-dependent and seems they can ask whatever they'd like.
Basic graph problems related to DFS, BFS
The following metrics were computed from 47 interview experiences for the Citadel SWE Intern role.
Citadel's interview process for their SWE Intern roles is extremely selective, failing the vast majority of engineers.
Candidates reported having very good feelings for Citadel's SWE Intern interview process.