Interviewed for SSE-1 Backend engineer at Dunzo. I have 6+ years of exp.

I had totally 7 rounds.

1. Discussion with co-founder
   • HLD of a peer-to-peer chat app backend design
2. DS/Algo
   • https://leetcode.com/problems/search-a-2d-matrix/
   • https://gfg/burn-the-binary-tree-starting-from-the-target-node/
3. HLD
   • HLD of music stream app - Spotify, Gaana
4. LLD
   • LLD of IRCTC - DB design
5. Service implementation
   • Multithreaded implementation of a coffee machine with multiple outlets - Given 5 hours on a holiday
6. Managerial round
   • Usual managerial questions
   • Project discussion
   • Design basic Leaderboard of Dream11 app - HLD
7. Bar raiser
   • Usual managerial questions
   • Project discussion
   • Design Instagram - Notify followers when someone uploads a pic

Result - Apparently, LLD and Bar Raiser didn't go well. They offered me SDE-II (downlevelled). I rejected it. :)

Edit - For people asking about Coffee machine implementation, it's a simple Java project on an IDE where you use multithreading concepts to simulate a coffee machine dispensing Latte, Cappucino etc at the same time (each thread brewing one item). You have to manage the inventory (quantity of ingredients - probably in a HashMap) while brewing the coffee. If you have your basics strong, this should be pretty straight forward.