Nextdoor Software Engineer interview questions

Recruiter reached out and scheduled tech screen which had 2 rounds of interview. Both interviews were for 1 hour each. No behavioral. 1st interview asked something similar to Secret Santa and started from very basic condition and slowly added contraints one by one. My solution worked for initial constraints but last case couldn't handle. With last constraint it felt almost the problem become an n-queens problem. For second round, interviewer asked storing the comments of a post which had references to its parent in such a way that its easy to traverse them and print the list of comments in hierarchical manner. Would say to practice storing objects and their references in a map, such that with dfs you can print those. Both interviewers tried to help out and were actively working with me on the solution. For second round, I took too much hint, may be that's why I didn't clear it.