RedBus interview experience Real time questions & tips from candidates to crack your interview
Software Engineer
RedBus
4 rounds | 6 Coding
problems
Selected Interview preparation journey
Preparation
Duration: 6 Months
Topics: Data Structures, Algorithms, OOPS, OS, DBMS, CN
Tip 1 : Focus mostly on data structure and algorithms, try to solve at least 3-4 problems daily if you're a college-going student or 1-2 if you're a working professional, on various platforms like LeetCode(preferred), GFG, Interviewbit (when the interview is close, best for company-wise prep). I think 250 + DSA problems from leetcode put you in a very good position of cracking most companies interview provided most of them are medium level problems.
Tip 2 : Apart from DSA, also try to do development side by side and make some decent projects to show on your resume.
Tip 3 : Never neglect Core CS Subjects, try to finish it from some youtube channels like gate smashers or knowledge gate, also you don't have to prepare all CS subjects as most companies ask only from DBMS, OS, and CN(computer Network)
Application process
Where: Other
Eligibility: No
Tip 1 : Mention only those things that you really know and have worked upon in the past
Tip 2 : Showcase your achievements like ranks in a coding contest like ICPC, Codeforces, CodeChef, etc or maybe in hackathons (this showcase that you're a really good developer to the recruiter)
Interview rounds
01
Round
Medium
Video Call
Duration40 Minutes
Interview date5 Oct 2021
Coding problem1
Introduce yourself
A lot of questions were asked on Javascript concepts like object destructuring, ES6 features, Hoisting, Closures, and some output-based questions were also asked because I had mentioned JavaScript on my resume.
I was also asked SQL queries that involved joins and aggregate functions
1. Zero Matrix
Easy
20m average time
80% success
0/40
Asked in companies
You are given a matrix 'MATRIX' of dimension 'N' x 'M'. Your task is to make all the elements of row 'i' and column 'j' equal to 0 if any element in the ith row or jth column of the matrix is 0.
Note:
1) The number of rows should be at least 1.
2) The number of columns should be at least 1.
3) For example, refer to the below matrix illustration:
Problem approach
Firstly I explained the brute force solution which uses the O(N*M) extra space, he then asked me to further optimize space then I explained the 0(1) space solution to the interviewer.
02
Round
Medium
Video Call
Duration40 Minutes
Interview date6 Oct 2021
Coding problem1
Introduce yourself
This round was mainly focused on checking my knowledge of Core-CS subjects.
The following things were asked: -
Coding question to solve which was based on two-pointer approach and I was asked to explain the approach in best time and space complexity.
Questions on OOPs Concept like inheritance, polymorphism, Abstract class vs interfaces with code examples.
Questions on Operating Systems Concepts like Round-Robin Scheduling Algorithm, Paging and segmentation difference, mutex vs semaphore, Deadlock.
Questions on DBMS like ACID properties, Normalization, and SQL queries which required the use of multiple joins and aggregated functions together.
1. Closest Sum
Moderate
30m average time
70% success
0/80
Asked in companies
Given an array 'ARR'' of 'N' integers and an integer 'target', your task is to find three integers in 'ARR' such that the sum is closest to the target.
Note
In the case of two closest sums, print the smallest sum.
Problem approach
Firstly I explained the 0(n^2) approach after that interviewer asked me to further optimize it, then I explained to him the 0(nlogn) approach in which I first sorted the array to be sorted, and then applied the two-pointer approach.
03
Round
Medium
Video Call
Duration45 Minutes
Interview date8 Oct 2021
Coding problem2
Introduce yourself
Coding question to solve (Sort Linked List )
Design Email Verification System
Questions based on projects mentioned in the resume.
1. System Design Question
Design an Email Verification Sytems
Problem approach
Tip 1 : Ask the interviewer about all the requirements and edge cases before starting with the solution.
Tip 2 : don't hesitate in asking anything.
Tip 3 : Try to give a simple solution first which is feasible and then you can move to a better solution while discussing with the interviewer.
2. MergeSort Linked List
Moderate
30m average time
60% success
0/80
Asked in companies
For a given Singly Linked List of integers, sort the list using the 'Merge Sort' algorithm.
Problem approach
I used the merge sort technique for this that run in 0(nlogn) time
04
Round
Easy
HR Round
Duration25 Minutes
Interview date11 Oct 2021
Coding problem2
1. Basic HR Questions
Introduce yourself
Questions and discussions regarding projects.
HR questions like what was the most difficult situation encountered in life and how did you manage to come out of it, strengths and weaknesses.
Why redbus?
Which technology would you like to work on in redbus
2. Puzzle
Gold Bar Puzzle
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 the purpose of the return keyword?
Choose another skill to practice
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