About less than a week after I submitted my application online, I got a phone interview with a Yahoo employer.

I was asked to write a coding question and implement a stack.

Several days later, I got the onsite interview. The interview was pretty intense. I had four hours of interviews in a row and talked to four employers.

They were very friendly. I tried my best and I felt I did well. But unluckily, I didn't get the offer.

Find the longest child in the binary tree.