The recruiter contacted me and asked if I'd be interested in interviewing for the position.

I went through a phone screening where I coded on a shared editor.

I breezed through the interview and got the solutions, then optimized them as needed. The interviewer seemed happy with my solution; however, I received a "no go" call the next day, pretty confused as to what went wrong.

They refused to disclose the reason due to their privacy policy :(

Implement the most efficient structure to store multiple strings.