It was an onsite interview, following a phone interview one week ago. There were four rounds of technical interviews, each lasting around 45 minutes. Problem-solving comprised the majority of the time, with some behavioral questions and casual conversation included.

Given a list of song names and a song name, append the song name to the end of the list if it hasn't appeared before. Otherwise, remove its previous appearance first, then append it to the end.

Given a string representing an absolute path and a target string, return a map whose keys are all files under the input path (including those under sub-directories), and values are boolean flags indicating whether each file contains the target string.

Given an array with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order red, white, and blue.

Implementing a factorial function.