Snapdeal Interview Experience | Set 12 (For Senior Software Developer)

I gave this interview for Senior Software Developer Role.

Round 1:
Lots of puzzles and algo’s. The interviewer didn’t let me write code for anything, the moment I say efficient algorithm he moved next question.

Q1. A tree is represented in the form of array. Where index(i) of the array represent value of a node and the value inside(A[i]) represent the parent index of the tree.
Value corresponding to root is -1. Construct the tree.
For Eg: 1,-1,1,2,3,1 index 1 is root, with three children at indexes (0, 2 and 5) and index 3 is a child of 2, index 4 is a child of index 3
Initially I did it O(n*n) and later with the help of extra space O(n), I did it in O(n)

Q2. We played a game, there are n coins where each player has to pick up coins min 1 and max 6 one by one and the person who picks the last coin is the looser
something like http://www.quora.com/Given-n-coins-for-two-players-playing-a-game-Each-player-can-pick-at-least-1-and-at-most-5-coins-in-one-turn-The-player-who-picks-the-last-coin-loses-the-game-If-they-play-optimally-which-player-will-win-the-game
We played two such sets and both times the interviewer won and he asked me to find the logic behind it, luckily I could crack it using the two sample games I played.

Q3. http://www.braingle.in/brainteasers/teaser.php?op=2&id=9653&comm=0
After long discussion I could answer this as well, with some hints.

Round 2:
This round was a mix of core java and Designing
Q1. Categories of different books in a library is stored in database as
Category => String Name ,String Id,String ParentCategory_Id
Null ->Physics->Electronics->Current
Categories are infinite and sub categories are infinite
All Categories with the parentCategory_Id null are the first level categories, and under each such category we will have multiple sub categories.

He will give me an array_list with these tuples and I have to generate entire tree.

I wrote a class Node{ String Id, String name, List children } and I return a node with null name and null Id as the root.

Q2. A user logged in a page and the load balancer is sending each request of a user to different servers(instances). I want session_data in all servers, how to do this?

Q3. He asked me, if I know this. Collections.SynchronizedList(ArrayList lis)
I said no and then explained what it is and asked me to implement.

Round 3:
This round went pretty good
Q1. How java files are loaded into tom cat server
Q2. How different versions of the dependency package resolve
Q3. Two classes with same name in diff package, do they overload
Q4. Two classes under same package(I told him compiler will throw error) and then asked which class will throw error first and few more generic java questions.
Q5. Asked me to design a app like ola cab.

All Practice Problems for Snapdeal !