Amazon Internship Interview Experience

Aptitude and Coding Round
The coding round had two questions 1 was quite hard which was DP problem no one was able to solve it other was easy can be done applying simple sorting logic
Aptitude questions contained questions related to java SQL and basic c/c++ knowledge and programming
A total of around 150 students sat for the test out of which 19 were shortlisted

Interviews

The HR came and explained to us about the format and internship opportunity job description and location
There were two technical interviews and No HR interview

Interview 1

The Interviewer was very nice calm and composed he told me the basic of how the interview will be and asked for any doubts.
The first question was to write a code for balancing brackets in an equation
I was shocked to hear it but it was the one I asked him again whether its the right question and he said yes
I wrote the code checked he was overlooking it and grabbed the paper when he understood that I knew the logic and proper syntax
The second question was to find the longest increasing subarray
Longest increasing subarray
The solution was similar to this approach I went through my code and found a mistake corrected it and then gave it to him
The point checking your code/ answer the interviewer is not in a hurry, so take your time check and then submit it
The last question was quite tricky I had never seen it
It was based on group theory and dependencies
Lets say there’s a relation A = {B, C, D}
B = {Z, X}
i.e. A is dependent on B C and D and consequently on Z and X
So relations of A are
A -> B, A-> C, A->D, A->Z, A->X
So the question was to find the dependencies of all the variables
I used an approach of Hash tables which was not full proof and efficient but the interviewer helped me work out a better solution which was not efficient but correct
And that was it for interview 1 I asked a few questions about the life in Amazon and then I left the room
9 students were shortlisted for the round 2

Interview 2

Interviewer welcomed asked me some general questions about myself it was kinda pseudo HR interview in the beginning. He asked me to tell about myself wrt to coding. I told about my encounters with coding my projects and research projects.
He asked me whether I’m good with Theory of Computation I said I’m not confident sir
The same he asked me for JAVA and replied the same answer I was not happy with this but I had decided to tell the truth no matter
He then asked about OOP I said sir I can try and he asked about Virtual Memory
I was able to answer the question and explain the concept
The next question was to write a code to traverse a binary tree in alternate even level order traversal
If a tree has levels starting from 0, 1, 2, 3 and so on print the even levels
I.e. print 0th level, 2nd level and so on

https://www.geeksforgeeks.org/print-all-the-levels-with-odd-and-even-number-of-nodes-in-it-set-2/
I requested for some time and after 5 mins I thought about using zigzag level order traversal by using a proposed solution
We will traverse the tree in a zig zag manner and store the levels in hash table
And at the end we print even level entries.
He was satisfied with the answer and said instead of using two queues use only single queue
He helped me in devising a solution and we got an approach.
I was not asked to write the code for it.
And that’s it the second interview was also done

After 18 hours TPO mailed and I was selected for the Amazon Internship for SDE 1 position along with 6 others from my college VJTI