The interview process is long-drawn. Nokia HR seems to go into hibernation during the period between interviews before communicating the outcome (takes an average of 10+ days).

I underwent two telephonic tech interviews, then two panel interviews (each having a gap of at least 10-15 days).

Very unprofessional HR managers, lacking the basic etiquette of calling candidates promptly or planning multiple interviews together. You can sense unrest in the company. Totally not recommended if you already have a stable career.

Create a data structure having a key and multiple value pairing without using any inbuilt Java collections.

Outline how to create a custom messaging queue service from scratch.