Status: B. Tech [Tier-1]
Position: SDE1[University graduate] at Uber India
Location: Hyderabad, India
Date: 26 March 2022
Result - Selected

Online round (60 mints) -
3 Problems were asked -

1. https://leetcode.com/problems/longest-substring-without-repeating-characters/
2. Give n pairs(Let ith pair be denoted by (A, B)), you can chose any k indices(k is given in the input, n >= k), let the indices be i1, i2, ... ik. Find the minimum value of the expression (Min(B[i1], B[i2] .., B[ik]) * (A[i1] + A[i2] + A[i3] .....+A[ik])).
   Hint - Try sorting it with second pair and try fixing the value of Min(B[i1], B[i2] .., B[ik]) by iterating the pairs in desceding order and keep max heap of size k for the second part of the expression.
3. Given n nodes in a tree, all the edges of the tree are directed one of the vertices. All edges are are assigned a cost and its passed as a parameter in the function.
   Let's say there's an edge between two vertex a and b, and it is directed from a -> b. Now, if we travel from a to b, we have to pay cost c (assigned to edge a->b), whereas if we travel from b to a, we incur 0 cost.
   We can travel in any direction with the rule regarding cost incurred stated above.
   We consider all the nodes in the tree root one by one. For each root, we evaluate the maximum cost to reach a leaf. Return the minimum of the values computed above for each root. (n ~ 100000)
   Hint - Dp on trees.

My performance - I was out of practice so solved the first 2 and wrote brute force for the third one.
Verdict - Selected for interviews
PS- I got to know that brute force of last 2 problems and complete solve of 1st problem was enough to clear for interviews.

Round 1[Problem Solving] (45 mints) -
Base Problem - construct complete binary tree given array on gfg
The problem was not asked straight away, it was presented in very confusing format, upon asking for clarifications, it boiled down to the above base problem. Was asked 5-6 follow up questions(working code for each was expected). All the questions asked to me were simple(was kindof lucky and the interviewer was also nice). Wrapped the working code and edge cases within 30 mints. Interviewer was impressed and we went on discussing about Uber and its culture for the remaining 15 mints.

Round 2[Machine Coding] (45 mints) -
In this round, they expect you to implement class based solution to an abstract problem, where you have to ask interviewer about the remaining details on the go.
I was given leaderboard design problem (I had seen this one before from online experiences), 5 mints after pitching me this problem, interviewer realized that I knew it and asked me point blank if I had solved it. Told him yes, and then he gave me 2 problems to solve instead of 1(Because I knew the first one). Wrapped this one up in the next 10 mints.
Second problem was designing Restaurant menu which contains dishes and each dish has a name, price and list of ingredients its made up of. There were 6 functionalities which were expected from me to be implemented -

1. Add a dish to restaurant menu
2. Remove a dish from restaurant menu
3. Add an ingredient to a dish
4. Given a list of dishes ordered, return the total amount of bill taking in account tax.
5. Given an ingredient, return the list of all the dishes containing that ingredient.
6. Return all the dishes served in a restaurant.

Hint - Created 2 classes, one for dishes which had only name, and other for restaurant menu having other attributes. Used 3-4 maps for optimized approach in the functionalities listed above.

Was able to compile my code with just a simple very naive bug which was a typo actually. Interviewer was also very helpful and probably one of the best ones I've met so far. This was the best round, as I solved 2 problems instead of 1 in the same timeframe.

Round 3[HR + Technical] (45 mints) -
In this round, I was asked HR related questions for the first 15 mints and technical for the rest 30 mints. HR questions were like what is your biggest weakness, tell me about a time when you got into conflict with your mentor etc. I had experience in Cryptography, so was asked about blockchain and RSA algorithm.
Then, I was grilled about my next few projects written in the resume which were all DBMS based. I was asked some basics of MySQL. Now, around 25 mints remaining in the round, I was asked to design DBMS for bookmyshow, wherein the main functionality expected was that a user searches for a cinema and books a movie show. I wasn't prepared for DBMS design well as I was out of practice. Then, I started with listing the requirements and creating some tables and connecting them whilst explaining.
I was then asked a follow up question - How will you handle multiple concurrent users? Hint - Told them to store their transaction time in another alternative table and tentatively book their seats. Roll back, if transaction fails or timer runs out.
DBMS design was not very good as I was a bit nervous while solving this part. Overall, this round went okay/good.

Verdict : Selected😊