Red Hat interview experience Real time questions & tips from candidates to crack your interview
SDE - Intern
Red Hat
3 rounds | 5 Coding
problems
Selected Interview preparation journey
Preparation
Duration: 6 Months
Topics: Web Development, Backend Development, DevOps Basics, Data Structures, System Design, Computer Science Basics
Tip 1 : Contribute to open-source projects and have good projects in your resume and portfolio.
Tip 2 : Practice the basics of DSA and Problem Solving (solve at least 200 popular questions on LeetCode)
Tip 3 : Have an in-depth knowledge of Computer Science basics like OOPS, DBMS, Computer Networks etc.
Tip 4 : Have a completely knowledge and understanding for everything in your resume and your projects.
Application process
Where: Linkedin
Eligibility: No Criteria
Tip 1 : Have in-depth knowledge of everything you've put in your resume.
Tip 2 : Only write things that are relevant to the position (don't put stuff nobody is interested in)
Tip 3 : Create your resume in a format that is easy to read.
Interview rounds
01
Round
Medium
Online Coding Interview
Duration90 Minutes
Interview date12 Nov 2021
Coding problem2
It was a Online Hackerrank test with 2 coding questions and 20 mcq's.
1. Subtree of Another Tree
Easy
10m average time
90% success
0/40
Asked in companies
Given two binary trees T and S, check whether tree S has exactly the same structure and node values with a subtree of T, i.e., check if tree S is a subtree of the tree T.
A subtree of a tree T is a tree S consisting of a node in T and all of its descendants in T. The subtree corresponding to the root node is the entire tree; the subtree corresponding to any other node is called a proper subtree.
Problem approach
Given two binary trees, check if the first tree is subtree of the second one. A subtree of a tree T is a tree S consisting of a node in T and all of its descendants in T. The subtree corresponding to the root node is the entire tree; the subtree corresponding to any other node is called a proper subtree.
Traverse the tree T in preorder fashion. For every visited node in the traversal, see if the subtree rooted with this node is identical to S.
2. Merge LinkedList
Easy
20m average time
70% success
0/40
Asked in companies
You are given two LinkedList of length ‘N’. Your task is to insert the elements of the second LinkedList in the first LinkedList at the alternate positions.
For example: Let 1 -> 3 -> 5 be the first LinkedList and 2 -> 4 -> 6 be the second LinkedList. Then after merging the first LinkedList will look like 1 -> 2 -> 3 -> 4 -> 5 -> 6.
Problem approach
The idea is to run a loop while there are available positions in first loop and insert nodes of second list by changing pointers.
The nodes of the second list should only be inserted when there are positions available in the first list and here the second list has more nodes than the first. To put it simply, the second list can only be inserted if the nodes in it are less than or equal to the nodes in the first list.
02
Round
Medium
Video Call
Duration50 minuites
Interview date9 Dec 2021
Coding problem2
This round was an Interview round mix of Data Structure problems and javascript and golang questions. The Interviewer began by asking questions regarding the tree that required the bfs traversal and dynamic programming.
These were followed by some questions on Backend Development regarding how DNS works and what happens under the hood when we search for the website in the browser, the interviewer went into really minute details.
After this, some questions were there related to the syntax of Javascript and Golang and they majorly involved the use of basic data structures and inbuilt function usage for the particular languages. Some functions like the FIbbonacci were asked to code in both js and go. The interviewer just wanted to understand that I know the basics of the languages.
1. Maximum Depth Of A Binary Tree
Easy
15m average time
85% success
0/40
Asked in companies
You are given the root node of a binary tree with N nodes, whose nodes have integer values. Your task is to find the maximum depth of the given Binary tree.
Depth of a binary tree is the same as its height. In simpler terms, you have to find the total number of nodes encountered while moving from the root node to the farthest leaf node, along the longest path of the binary tree.
Example:-
If we are given the above binary tree as input then moving from root node(5) to the farthest leaf node(50), the path formed will be [ 5->10->25->35->40->45->50 ]. The total number of nodes encountered is 7, therefore the maximum depth of the binary tree is 7.
Problem approach
The algorithm uses recursion to calculate the maximum height:
Recursively calculate the height of the tree to the left of the root.
Recursively calculate the height of the tree to the right of the root.
Pick the larger height from the two answers and add one to it (to account for the root node).
2. Minimum Coins
Moderate
30m average time
70% success
0/80
Asked in companies
Bob went to his favourite bakery to buy some pastries. After picking up his favourite pastries his total bill was P cents. Bob lives in Berland where all the money is in the form of coins with denominations {1, 2, 5, 10, 20, 50, 100, 500, 1000}.
Bob is not very good at maths and thinks fewer coins mean less money and he will be happy if he gives minimum number of coins to the shopkeeper. Help Bob to find the minimum number of coins that sums to P cents (assume that Bob has an infinite number of coins of all denominations).
Problem approach
You may assume that you have an infinite number of each kind of coin. The solution algorithm uses a backtracking technique to generate all combinations of coin frequencies [x1...xn] in the range (0, Si/Ci) which satisfies the constraints above. It makes a sum of the combinations and returns their minimum or -1−1 in case there is no acceptable combination.
03
Round
Easy
Video Call
Duration40 minutes
Interview date19 Sep 2022
Coding problem1
In this round, a Senior SDE from the team focused mainly on my resume and walked through everything that I wrote in my resume. After some time he picked one of my personal projects that I've mentioned in my resume and asked me to scale it to the enterprise level and go through each and every step regarding how I will achieve that. This discussion included everything from scalability, the tech stack I would use and the features that I would implement that could actually solve a real-world problem.
1. System Design Questions
What do you understand by load balancing? Why is it important in system design? Implement Load Balancing in a currently existing project like a Ticket Booking system.
Scale any of your currently existing projects in your resume to 1 Lakh users. What steps will you take to do so?
Problem approach
In simple terms, scalability is the ability of your web application to cope with an increasing number of users concurrently interacting with the app. Consequently, a scalable web application is one that performs equally well with one or a thousand users and stands ups and downs of the traffic. Answer according to that.
Here's your problem of the day 
Solving this problem will increase your chance to get selected in this company
Skill covered: Programming
What is recursion?
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