American Express Interview Experience | Off-Campus

Round 1:

The first round was a hackathon(coding contest) conducted on Hackerearth platform. There were three coding questions, two questions were based on arrays and the third question is based on graphs. The overall difficulty of the exam is medium. I could solve the first two questions completely.

I got a call after 15 days that I have cleared the online round and an interview was scheduled.

Round 2:

The interviewer asked about myself. As most of my projects are on data science, she asked some basic questions of data science and probability. 

Questions:

1. What is univariate and bivariate data
2. What is long and wide data
3. There are two girls, given one of them is a girl what is the probability that both of them are girls
4. What is normal distribution?
5. Can mean and variance can be the same? When will they be different?

           After 10 days I got a call that I have been selected for the next round.

Round 3:

In this round, the interviewer asked about basic data structures and algorithms followed by a puzzle.

Questions:

1. What is multithreading?
2. What is the difference between hashmap and hashtable
3. What is hash function and how to choose it?
4. How does a text editor work under the hood(in terms of data structures)?
5. famous horse puzzle though I don’t know the solution before, I tried to come close to answer and he is satisfied.

Round 4:

This interview was taken by one of the Directors of Engineering. He was very gentle and helpful during the interview.

Questions:

1. Given an array, find the longest consecutive sequence. You can find it  here.
2. Follow up is that, if there is zero in the array, it can be treated as any number. Then how to find the longest consecutive sequence.

(Actually, this question can be solved easily by hashing, but I did not get that Idea. I sorted and the array and explained a binary search approach. He liked the approach and discussed the bottlenecks of my approach. He asked me to screen share and explain my code on the editor and he was helping while I was solving)

      3. How does a dynamic array created and what is it’s time complexity? 

After a week or so,   I got a mail that, they would like to offer me a full-time position at their organization.

Some of the things to remember while giving interviews to Amex:

1. While applying revise resume thoroughly, if your resume is relevant to the role they are looking for, there will be a high chance that you will be qualified for the first round.
2.  All the interviews will be held on the Cisco WebEx platform, make sure you add the browser extension prior interview.
3.  The interviews are scheduled for 30 min. Make sure you have a good internet connection for that scheduled time.

Hope it helps!