Google Poland L4 Interview experience.

Total Calls = 5;

HR Reached out on LinkedIn for an opportunity in Poland. Asks me to book a slot for a call.

1. 30 mins call: Asks basic questions, language preference, how much time would I take for revision etc. Then schedules a screening round.

2. 45 mins screening round: A question was given on encoding and decoding a DAG (Directed Acyclic Graph) with a follow up of including cycles as well.

I asked clarifying questions, created examples and edge cases, thought out loud and verbally kept explaining while writing clean code with proper methods and proper indentations. Did the dry run on completion.

I coded the solution for DAG and told what could we do for including the cycle information as well. Interviewer seemed happy. 2 weeks later, I received a call to schedule further interviews.

2 DSA rounds and 1 googleyness rounds were scheduled after about 20 days.

3. Round One - 45 mins DSA round: Interviewer gives me a question on parking lot where I would be given an array of pairs(vehicleType, slots) and another array of pairs(vehicleType, costPerMin)

Three functions were given:

initialize(vector<pair<string, int>> slotsPerType, vector<pair<string, int>> costPerMinPerType);

bool onEnter(string plateNumber);

int onExit(string plateNumber); // returns calculated cost & -1 otherwise

Again, I asked for clarifying questions, thought out loud, wrote clean code with different methods and proper indentation while explaining every line, made an example, did the dry run and had already covered the edge cases.

Interviewer told me to write unit test cases. I wrote some tests in main method and iterated over them to check if those 3 methods were working.

Interviewer was fine with the code but said I was expecting you to write unit test cases and end to end code but the time was over.

It felt awkward to hear something like that. I mailed the HR about the feedback.

4. Round two - 45 mins DSA round: Interviewr gave me a question to create a custom LinkedList which would store three things:
value, pointer to next node and a string which contains hash of current value as well hash of next node's hash
If the next node doesn't exist, it would assume the next node has an empty string as hash.

Again, I asked clarifying questions, made an example, thought out loud while explaining, wrote clean code with different methods and proper indentation while explaining every line and the interviewer seemed happy.

I made a class for linkedlist and a class for node.
LinkedList class had addNode function

Then he asked me to write a function which would validate the linkedlist. If the hash value of a node is tampered, then I should return false otherwise if the hash of all nodes are good, then true.

I coded that as well and the interviewer seemed happy. In the end we talked about how the onboarding looks like.

5. Round three - 45 mins Googleyness round: Some behavioural questions which I did well and we had back and forth discussions and he seemed happy.

Verdict: The very next day in the morning, I woke up, was scrolling my phone while I receive a call with Google written over it.
The recruiter asks for my feedback.

Then tells me we are not moving forward this time. There's a cool down of 12 months after which I can apply again.

I asked for a feedback, he says I do not have a feedback but in general, I would suggest keep doing what you were doing and keep practicing DSA and coding then apply again after 12 months

I asked if he could suggest me the areas I need to focus, that would be very helpful. But, he again gave a very generic reply and said he didn't have a feedback.

After the call, I asked him that the decision from the committee usually comes after 7-10 business days. Was the decision taken by the committee? He replied that it was a team decision not from the hiring committee.

Everything felt terrible in the end.

Let me know in the comment about what could be the reason for the rejection.