It was pretty hard. The initial problem was simple, but the addition required a Trie solution I did not know at the time. So I guess you should study data structures and how to implement them.
String matching with tries solution.
The following metrics were computed from 10 interview experiences for the Whatnot Software Engineer (Internship) role in United States.
Whatnot's interview process for their Software Engineer (Internship) roles in the United States is extremely selective, failing the vast majority of engineers.
Candidates reported having very good feelings for Whatnot's Software Engineer (Internship) interview process in United States.