Wayfair Software Engineer-Labs interview questions

I got the interview on employee referral, I had a online coding test which had 3 questions. The first one was to find a bug in the code which was a bit tricky, second was a problem of implementing a pattern to switch on light bulbs and final one was to implement a mathematical equations.

Phone round with recruiter followed by submission of projects and then online coding test. This was followed by a technical interview where they went through solution submitted for online coding test. They asked about how did the solve the problem. Technical phone round accuracy matters.