Google Software Engineer Interview Experience — Perfect Wake Number Coding Round, BQ Rescheduled

The R1 coding interviewer was very encouraging the whole way through (thanks to him), but I was too nervous and didn't perform very well.

First, the initial problem. A "perfect wake number" is defined as:

• no 0
• no repeated digits
• for every digit, its two adjacent digits are not higher than that digit

Write a function isPerfectWakeNumber(n: int). For example, 123 should return false.

I used brute force overall, with time complexity n*m.

Then the follow-up: how many perfect wake numbers are there in the range [1, 9999]? The interviewer was also very patient and made it easier for me, asking how I would think about it if I only considered the first two digits. I figured it could be done with subset backtracking, but in the end I didn't finish writing the whole method.

The BQ round got rescheduled, but overall I don't think I'm likely to pass.