Flexport phone screen

just did an phone screen with a full stack engineer from Flexport. Today i got a “thank you” letter from their recruiter.

Here is the feedback from the interviewer:

the code wasn't really clean to begin with and it took too long to come up with a working solution for part 1 and never got a working one for part 2 of the problem.

Here are my feelings:
0) I need more practices to be a better coder under stress

1) An interactive interview session is more productive
In this case, I was given a coding question and asked to implement, and after that I was asked to run the code with edge test cases. While during my implementation and debugging, I was trying to think loudly but got very few responses. Most of the time what I heard was keyboard clicking over the phone. I would partially attribute the mismatched expectation on the 2nd part to miscommunication: I misunderstood the requirement, but I did describe what I was going to do before I started coding, and the interviewer let me go along that direction until the end. It would be trivial change on my code to fit the requirement, which I described to the interviewer when there were 8 minutes left, but interviewer didn't let me make the change.

2) The programming environment matters when coding under sttress
It was my first time to use codepad and it seemed there was something strange to check null there, which I spent ~5 minutes to figure it out.

3) Flexport's bar is really high.
Given ~45 minutes (60 minutes, - 5 minutes introduction, - 2 minutes problem statement, -8 minutes Q&A) , understand a coding problem, implement "clean" code to "begin with" under an unfamiliar environment, run and debug the code, cover edge cases. After that, given 2nd requirement, make the code work again. All these are under watch without clues of direction and code cleanliness. The more difficult part is, during the process, it has to smooth and accurate without showing apparent struggling.