The first stage was the OA, which consisted of two questions to be answered within 90 minutes. I did not pass all the test cases on the second question before time expired, but I was still offered a technical phone interview.

The second stage was the technical phone interview. The interviewer seemed inexperienced, or perhaps hadn't fully reviewed the problem himself. He presented a problem that could be solved in two ways.

One approach was straightforward if a tree structure was used, but this required assuming the availability of many other functions. The other approach was more difficult and would have required a significant amount of time to implement.

I chose to pursue the second method. Before I could dive in and ask if it was acceptable, he said it was. When I became stuck and asked for assistance, he was unable to help. At the end, he mentioned, "Oh, the tree structure was the one I wanted you to use..."

Medium-Hard on Leetcode