Amazon Interview | (On-Campus For Internship)

It was a great experience with Amazon. The articles on GFG are really very helpful.

It consists of two rounds.

1) Online Coding Round

Online assessment: It consists of four sections:
*  Code debugging section (20 minutes): 7 questions were asked in this section. (Simple code)

*  Reasoning ability section (35 minutes): 24 questions were asked in this section and you will not be able to skip and return to problems.

*  Coding section (70 minutes) : 2 Question:

1. Find all pair in an unsorted array with sum less than k. Initially, I tried to solve in order of O(n) but failed to do. There were no constraints, so I solve this question using brute force (without TLE).
2. The second problem was a bit similar to rat in the maze problem but the destination can be anywhere. There are multiple approaches to solve this problem. I used backtracking to solve this problem.

*  Workstyle survey (10 minutes): Fill this seriously, who knows this also counts.
Totally 15 people got selected.

2) Technical interview:

There were 4 different interviews panels, I was among the first one whose name was called. We shook hands and exchanged greetings. The interviewer was doing something on his laptop. So, I asked some random question about him (I think that left a good impression).

He asked me to introduce myself. Then we talked about projects and my participation in GSoC (he wasn’t aware of GSoC), open source and what was my job as GCI (Google Code-In) – mentor, how I introduced open source to GCI students and all that stuff). He asked me about my participation in competitive programming contests. I told him, I am not a regular competitive programmer but participate occasionally.

Then he asked the first question, Check for Symmetric Binary Tree. He first asked the approach. I told him about my approach using the queue data structure. Then he asked me to write code on paper. And he was continuously asking me, if you get stuck then ask me. He even offered me coffee (of course I rejected it). After writing code, he pointed about what is this node and I missed one corner test code too. So, then I defined the structure of the node and considered the corner test case. Again, he asked me to write a code of recursive method (this is too easy). We discussed the complexity of both methods. He also asked me about the different version of the GNU compilers and some in-built functions that are available for the queue data structure in STL and their complexity and implementations.

Then he asked a second question, Next Greater Element. He explained this question wrong. So my new question became for each A[i] : output will be min(A[i+1] to A[n]) >= A[i].

For example:

Input: {13, 6, 7, 14, 9, 10}

Output: { 14, 7, 9, -1, 10, -1}

I took the time to solve this question. He gave me a hint but finally, I solved this problem using an ordered map (he gave a hint to do from stack data structure). He was a bit confused when I used the map but I explained it to him everything. Then he asked me to write code (did this without any error) and the internal working of the ordered map and difference between ordered and unordered map. We discuss the complexity of each function of both data structure.

He asked whether I have a question for him or not. I asked about the intern projects and in which team I will go if selected. We discussed work culture at Amazon. We also had 5 minutes discussion on delivery services and how to improve it.

Suggestions: Be confident in your approach and try to make conversation with the interviewer as they are sure to help you out. If you don’t know anything then say no to them instead of bluffing. Practice code on the paper because they really need good code without any error (try to have a good indentation and define class if you are using). Put only those projects on the resume which you had done genuinely (at least don’t get caught if you fake it) and make sure you know everything about your projects in great depth and details. For Amazon, the best way for practice is GeeksForGeeks Amazon internship experiences archive. It helped me a lot at the last moment. Also, be sure you can speak about all the things you have done. They may ask the purpose of your project, why this framework is used instead of other and even ask to write code.