Friday, July 19, 2019

Case study: My Facebook phone screen on July 17. 2019

July 19, 2019

Introduction


It is a good idea to write a case study about my past phone screen from Facebook. I like to document how good the interviewer is to manage the time, expectation, and handle the assessment task in such efficient way.

Case study


I got a call on 10:15 AM, the interviewer introduced himself, what he works on in daily job, and asked a simple question. He told me that he likes to end the interview at 10:56, I checked the time when he said that. It was 10:17. He planned to spend 39 minutes to ask interview algorithm. He will give me five minutes to ask questions.

He copied and pasted the question, and then he said that he will read the problem statement word by word, so he gave me time to read and think about the statement.

I thought about a few minutes, and I shared my idea, he liked my idea. He told me that I could start to write the code. He asked me to think out loud.

The algorithm is not a hard algorithm But I did say that I am thinking about how to determine the position in the array. The interviewer gave me hint right away, but only good enough for me to come out the idea to solve it in less than one line of code.

I finished the coding, and then reviewed my code, I found the code was buggy. I talked about two edge cases. The interviewer gave me second hint what to handle about edge case, I took his advice. I just added a few lines of code.

I checked the time that it is 10:28 or 10:38, so I was asked to solve the second algorithm. I believed that It is a hard level algorithm. And I had ideas how to solve the problem, but I did not have good design for possible issues in my choice.

This is most challenging part of problem solving. I had to learn through how to work with the interviewer, he just quickly gave me all kinds of test cases, helped me to think thoroughly about the problem. I was nervous, but I knew that it is important to listen and think about test cases he gave, and I was so surprised that I came out the idea how to make change of my design.

The interviewer said that he believed that I can code the algorithm if I am given the time. That is wonderful experience.

Actionable Items


I do know that a strong algorithm problem solver can come out the idea in less than five minutes; but it takes me over 20 minutes to work on hard level algorithm, I also need a few hints to change my design.

I think time is so critical in official phone screen. I understand that the interviewer will find out if I can perform under pressure, and how focus I can ...




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