Meta Software Engineer interview questions

The interviewer was very friendly, and we chatted some after he introduced himself and his projects. He asked me to design and implement algorithms that correct typos, offering guidance, encouragement, and confirmation along the way. It felt really good to voice my thoughts along the way, and it helped him to know what I'm thinking. He asked a few follow-up questions afterwords about my code (which I think he made up on the spot). I answered and we agreed on the answers. Next, he presented a scenario that we formed a web startup featuring that code at its core. So then we discussed how to use more memory and less CPU, and how to scale up the company. At the end I asked him his thought about fb and what he did before working there. The experience was very fun.

I was first called by a FB recruiter and we chatted about 15 min about my general background information. I then was followed up with a phone interview with a FB engineer. He seems to be an experienced engineer. He started with a common background question like challenge of current project. Then, he asked me to design the Facebook Credit system. I proceeded with talking about I would started with designing the backend of the system, for example a ER diagram that would outline the relationship between existing user information and the new information related to the FB Credit system. I was a little nervous at the beginning, but the interviewer jumped in and gave me some help. He then asked me how would the total credit points of a user be calculated based on my design. For that question, I answered how the data is delivered to user from end to end in a multi-tiered web application. Next is the programing question (write a function to convert an ASCII representation of a positive integer to it's numeric value). I had a subtle bug in my code, but in general I got it right. I coded in PHP, the interviewer is satisfied with it since FB uses lots of PHP. The last 5 min was for me to ask him some questions. The interviewer was very professional and helpful during the interview. He was able to follow my thoughts and provide hints.