Applied on the company website.

Received an email the next day inviting me to take an online coding challenge on HackerRank.

Completed the challenge, answering all questions perfectly, and was contacted by HR to schedule a phone interview.

The interview consisted of the same question with progressively more difficult variants, implemented using a collaborative coding tool (also HackerRank).

At the end, the interviewer asked if I had any questions.

Given an unsorted list of integers, return true if the list contains any duplicates and false if it does not contain any duplicates. You do not have to identify the duplicate value.

Given an unsorted list of integers, return true if the list contains any duplicates within k indices of each element. Do it faster than O(n^2).

Given an unsorted list of integers, return true if the list contains any fuzzy duplicates within k indices of each element. A fuzzy duplicate is another integer within d of the original integer. Example: If d=4, then 6 is a fuzzy duplicate of 3, but 8 is not. Do it faster than O(n^2).