Applied through a recruiter and received a phone interview, followed by an on-site invitation within a week. I took three weeks to prepare before heading to the Mountain View campus for the on-site interviews.

The phone interview focused on a single question related to anagrams and string matching. The interviewer allowed me to code an O(n^2) solution and then guided me to optimize it to O(n), asking me to code the second approach as well. I was given time to ask questions at the end, and the interviewer was very helpful throughout. I did notice the interviewer seemed to doze off for about 5-7 minutes while I was coding.

For the on-site interviews, I had five one-on-one sessions and one non-evaluated lunch interview. All five interviews were distinct and tested a broad range of topics, including strings, graphs, dynamic programming, and math/probability problems solvable with recursion. One interview specifically focused on data structure knowledge, requiring a few simple conceptual answers and two to three small coding questions.

Most interviewers were focused on typing/taking notes and began directly with questions, without introductions from either side. They did provide hints and ask follow-up questions on my approach. Many interviews extended until the next interviewer arrived. Forty-five minutes passed very quickly, and it was common to feel like questions weren't fully solved due to the continuous probing from interviewers until time ran out.

Overall, it was a pleasant experience, and the interviewers were direct. I never fully understood what went wrong, as the recruiter informed me they were not moving forward, citing a need for stronger coding ability and data structure knowledge – feedback that felt vague given my perception of solving the problems correctly.

They encouraged me to reapply after a year.

Finding the maximum length substring with certain conditions.

This is a graph traversal type question. Please use BFS, since DFS will incur a bigger call stack in the worst case.

Dynamic programming and generating a certain type of n-digit numbers can be solved using recursion.