Meta Software Engineer interview questions

They asked me to code on Collabedit. The first question was finding the largest drop in a an array. The second question was implementing a regex matching function. My interview was not bad, but overall, I am not pleased with the hiring process in Facebook. The interviewer was ignorant in my expert field.

HR responded pretty fast, then they scheduled a phone interview. During the interview - They introduced their group - Talked about my project and work experience - Asked me a coding question ( I list it blow, because it is difficult question for most people I think)