Google India - Sr Software Eng (L5) [Hired] | Interview Experience, Preparation Strategy and tips

Background

Education: Bachelor’s from Tier 2/3 College (not sure some state govt college)
Years of Experience: 6 years (Product based, mostly in MAANG)

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Application process

Applied through referral [However if I have strong resume for job requirement it will go through without referral as well (Applied for L4 in 2021 without referral)]

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After Resume Selection

Recruiter reachout for interviews date and explained the process. For L5, three round of DSA, one round of System design and one round of googlyness & leadership.

Recruiter told me System design and Leadership round will be conducted only if I clear DSA round ( at least 2 hire call in 3 rounds)

I will have options to have multiple round on same day or I can have it on different day as well
I had all rounds on different day (DSA had ~2/3 days of gap between each round)

For System design and Leadership round I took another 3/4 weeks

I took around 4 week to prepare ( I was already in interview mode, you can ask for more)
[My advice] I would suggest, do not hurry and take my time to prepare

Google Interview

Each round takes around 45mins, some of my round was extended to 60mins as well due to interviewers interest in follow up questions

Round 1 : DSA

Problem Statement
Given a single string which has space separated sorted numbers, determine whether a specific target number is present in the string.

E.g. Input: "1 23 34 123 453" Target: 123
Output: true

Tip: always ask follow up questions
This looks a straight forward problem of binary search but the way it should be implemented can be based on your follow up questions else you end up with solution which may not cover all the cases

• e.g. Since input is provided in string, numbers can be large like 10000's digit large which you cannot fit in regular numeric data type in most language

Solution

• I started with some straight forward brute force approach like, storing these into a list of integer and apply binary search.
• Apply linear search directly over the string
• Final solution was applying binary search directly over the string
• Based on follow up, constraint was that numbers would fit in numeric data type (So, I ended up coding Binary search)

My take

Asking follow up question helped me writing optimal and cleaner code.

Round 2 : DSA

I don't remember the exact problem, It was based on some timeseries logging information. Optimal solution was based on sliding window.

• I followed the same pattern, like asking follow up questions on problem statement and its constraint

My take

I found this round bit easier than the first one, as there was only one followup question was asked which my code was already handling

Round 3 : DSA

Problem was based on binary tree. It was standard binary tree problem which required some calculation on its leaf node

Solution Discussion
I provided the dfs (inorder) solution, however interviewer asked on if bfs can be applied which was like level order traversal.

Provided both the solution, fumbled a little bit in complexity analysis which I corrected when interviewer nudged me to think about different kind of trees.

Verdict: Got positive (hire / strong hire) feedback on all the DSA rounds.

Took 3/4 weeks to prepare for system design and Leadership round

Round 4 : System Design

I was asked to design small image/gifs/video hosting platform which does not require sign up.

Steps I followed

1. Requirement Gathering (spend ~4-5mins)

Gather all the information that I can, and before moving to the next steps, follow up with interview if they are good with current requirement and assumption.

2. Based on requirement, did some "Back of the envelope estimation"

Performed some math based on requirement.
Confirmed with interviewer on output and assumption
Tips: Write these down, so that I can come back to it for reference

3. Outlined the high level systems which will be used

Drew high level component for the system. and explain underlying tech that can be used. e.g. storing metadata in DB (relation/non-relational) and image on file bases on storage system like S3
Had indepth discussion on relational vs non-relational. I went ahead with no-sql based db to store meta data. Provided strong points on why, I am using this
Note : I did not provided loadbalancer, gateways, proxy at this point of time

4. Dig deeper into core component

Discussed the bottleneck of HLD components. Then introduced, tech that can be used to solve those issues like loadbalanacer, proxies (forward, backward). Cache to store metadata. Having a background image processing system to ensure images can be stored in different format to serve all kind of user (like slow internet etc)

5. Discussed multiple bottlenecks of system and handling of different solution

Zoomed into high level components to further break down the system and its responsibilities

6. Interviewer provided the new requirements which system should be able to handle.

Work done in step-4 & step-5 helped me in fitting these new requirements in incremental fashion rather the re-architecting the system

Discussion went for 80mins although time assigned was 60mins

My Take : System design

1. For Sr level, general expectation is I should drive the entire system design interview and interviewer should just ask scenario and I should explain how it is being currently handled or will be handled.
2. Keep providing my thought process to the interview and at the same time keep myself open to get the feedback and move in that direction

Verdict: Got positive (hire / strong hire) for both rounds

PS: Please don’t judge me for any grammar mistakes — this is my first time writing something like this. Just trying to give back to the community that helped me a lot during my preparation.

EDIT-1: Had to remove the external links for resources due to leetcode policy which disabled the post visiblity.
EDIT-2: If accessible, same post with external liks are available. [post with external link]
EDIT-3: Some Interview tip while interview is in progress

💡 During interview, do not hesistate to ask questions even if I think it is silly one.
💡 Do not assume anything. If assuming make sure interviewer and I are on same page about it
💡 Think loud, it provides interviewer to look into my thought process. E.g. I was taking about linear search and then storing each number in a list etc along with why it is not optimal etc and finally concluded the binary search
💡 If I get time at the end, do ask questions to my interviewer about their work, daily routine etc. I generally ask them to give me some brief intro about their work so that I can ask related questions instead of generic one

Edit-4 Binary Search on String code

Compensation Details

AMA in comments. I will try to answer as much as possible.