I had the onsite full loop of interviews on the same day:

• Behavioral
• 2 coding
• System design

Behavioral

I had a document from 3 years ago for an interview of that time, I just quickly updated it with newer stories. I don't remember the questions, they were the usual "Tell me about a time you received feedback" etc

Coding 1

1. 23. Merge k Sorted Lists

There was a change: implement a class that receives k sorted lists (array lists, not linked lists) in the constructor, with a method next() that returns the next smallest number of all the lists.

I proposed heap solution, I took a good time writing the code, had a few bugs and corrected them.

2. 146. LRU Cache

Got lucky because it was the last problem I solved when studying the day before lol. However I didn't implement the doubly linked list solution.

I asked when the recency should be updated, interviewer said on both get() and put(). I said that if it was only on put() I would just use a deque, but started thinking out loud about another data structure that would allow make it the get() method run in O(1). I suggested a simple linked list, discussed with interviewer and then started writing code. I didn't finish due to time.

I think he liked the question I asked him

Coding 2

Interviewer got really interested about something from my resume, spent the first 10 minutes of the interview talking about it. Got along really well lol

1. 215. Kth Largest Element in an Array

I proposed heap solution, he knew I knew about quickselect and said it's impossible to write it on time so I started with the heap and finished it.

2. 1570. Dot Product of Two Sparse Vectors

I proposed storing indices of non-zero elements, went ahead and coded it. No follow up from LeetCode.

We talked more after the problems, he liked my questions as well

System design

1. Design Instagram

When identifying the requirements the interviewer simplified the problem to only posting and following. This was a fullstack interview but I was focusing more on the backend. He asked a lot of things that I was missing as I was talking out loud, but I managed to follow up correctly I guess

Conclusions

Luckily I had already solved the 4 problems I got when preparing for the Screening interview. I could definitely had done better on the system design, but I guess it was good enough

I got no feedback, just a confirmation that an offer is coming

Keep practicing tagged problems and you got this!