Systems Development Engineer Intern

You are given an input string 'S'. Your task is to find and return all possible permutations of the input string.

Note:

1. The input string may contain the same characters, so there will also be the same permutations.

2. The order of permutation does not matter.

You have been given a Binary Tree of integers. You are supposed to return the level order traversal of the given tree.

For example:

For the given binary tree

The level order traversal will be {1,2,3,4,5,6,7}.

You are given an array of integers 'ARR' of length 'N' and an integer Target. Your task is to return all pairs of elements such that they add up to Target.

Note:

We cannot use the element at a given index twice.

Follow Up:

Try to do this problem in O(N) time complexity. 

 One of my projects involved managing a site, so he asked me, how would I handle if my site got huge traffic and I had to manage a lot of data, I told him how I’ll manage the database using indexing and database sharding if database sharding is implemented will the data be at a single server or distributed servers, which I was able to explain to him, and he was satisfied by my answer. 
OS questions: spooling and a few others I can’t recall. 
Networking questions: Explain the OSI model’s all layers with protocols of each layer, what are protocols of the transport layer, explain what is TCP and UDP, explain how the TCP mechanism works. 
How would you find network errors in transmission, and what type of errors are there, I told him we could analyze ICMP packets in pcap files in Wireshark , and told him about various errors like zero window, dup ack etc. 
Linux: He asked me all the Linux commands I could think of and explain their use, I was able to give him 10-15 commands with their use, he then asked about chmod, read and write permission, how they look and what denotes what in read and write permission structure, I was able to explain everything, and he was satisfied by my answer. 
What are immutable objects, the difference between overriding and overloading, what is operator overloading, the difference between run time and compile-time polymorphism, except immutability I was able to explain everything else with an example? 
He then explained what immutability meant.

Given two arrays ‘ARR’ and ‘BRR’ of size ‘N’ and ‘M’ respectively. Your task is to sort the elements of ‘ARR’ in such a way that the relative order among the elements will be the same as those are in ‘BRR’. For the elements not present in ‘BRR’, append them in the last in sorted order.

For example

Consider the arrays as ARR = { 9, 5, 8, 4, 6, 5 } and BRR = { 8, 4, 5 }
The output for the above example  is { 8, 4, 5, 5, 6, 9 }.

Note:

Elements of ‘BRR’ are non repeating.

He asked me what does an auto variable mean, how map sorts its keys, difference between map and unordered map’s working, and write down output for each iteration, then later he asked time complexity and space complexity of the code, I was able to explain everything, and he was satisfied. 
How would you check if a site is reachable? 
What is DNS, explain how it works. 
What happens when I type amazon.com in the URL
Explain TCP/IP and a 3-way handshake, what is SYN, ACK packets 
How does an API work, explain how a search query works on espn cricinfo website 

How will you rectify a broken site or a site that is not reachable? I told him that we’ll get a status code on the broken site and then I explained to him about different status codes like 1xx,2xx,3xx,4xx,5xx what each of these meant, and how we can possibly know what and which side is causing the error, and based on the deduction rectify it. He was pretty satisfied with my approach. 

Let us say your Linux server is running slow how would you deduce what is causing it and how will you rectify it, I told him about monitoring the resources using htop command in Linux and seeing which resource is being used more, since the server is running slow it is safe to assume that the server is running slow due to high CPU usage and based on this we can make some tweaks in the configuration file, he asked what tweaks exactly to which I was not able to answer as I was not sure, he said it’s fine and told me that he’s done with my interview and asked if I had any questions for him.