The interview process involved several stages:

• HR call
• Coding interview
• System design and other technical assessments.

There were numerous letters and notifications, and a platform was provided for interview preparation, along with other helpful resources. The hiring process felt technically advanced compared to my previous experiences.

The most disappointing aspect was the lack of detailed feedback. Responses were either "everything is good, we're moving forward" or "sorry to tell you, you're not a fit." When I specifically requested feedback on what went right and wrong during the coding interview, I received a response citing an NDA or something similar. It seemed that even though I solved the suggested problems, I somehow wasn't a good fit.

1. Write code to determine whether a string is a valid number. Some basic examples are given, but you can elaborate by providing your own examples of complex valid and invalid cases, such as: "-.5" or "001", etc. This challenge mostly depends on your creativity.

2. Given a binary tree with unique values in nodes, for a query of two different nodes, find the lowest common ancestor in this tree. "Given the tree" implies "given the root." A tree is a Directed Acyclic Graph (DAG), so no back edges from children to parent are presented (but you are expected to consider this and ask clarifying questions).