there were 2 stages: coding and algorithms. in coding i had to write methods and tests for a LazyArray, in agorithms there was a problem where i had to use set(i was writing in c++) but the interviewer asked me how else could i implement the code with all possble data structres, array, heap etc and analyse runtime of these alternative solutions

First, there was a brief HR interview 15-30min. The recruiter explains the whole hiring process, which consists of 4 interviews, including this one. The second and third interviews were on algorithms and data structures, and on system design.