Rolls-Royce Software Developer Intern Interview Questions and Answers

Round duration - 70 Minutes
Round difficulty - Medium

There were 5 people in the zoom meet, including me. Rest all 4 were interviewers, 3 from India and 1 from the United Kingdom.
They started with my introduction and then moved on to the questions from my resume, starting with my internship at Samsung Bangalore and then projects.
Then another interviewer asked about my weakness and strength. Then comes the turn of coding questions.
Starting with finding the minimum element in O(1) time, rotating the 2-D array by 90 degrees, OOPS questions were also asked like- polymorphism, abstraction, virtual class. Some OS questions were- cache, paging algorithms.
Then come my POR and other activities.

Q1. 
Kth Smallest Element Problem Statement
You are provided with an array of integers ARR of size N and an integer K. Your task is to find and return the K-th smallest value present in the array. All elements...read more
Ans. 
Find the K-th smallest element in an array of distinct integers.
• Sort the array and return the element at index K-1.

• Use a min-heap to find the K-th smallest element efficiently.

• Implement quickselect algorithm for optimal performance.
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Q2. 
Inplace Rotate Matrix 90 Degrees Anti-Clockwise
You are provided with a square matrix of non-negative integers of size 'N x N'. The task is to rotate this matrix by 90 degrees in an anti-clockwise directi...read more
Ans. 
Rotate a square matrix by 90 degrees anti-clockwise without using extra space.
• Iterate through each layer of the matrix from outer to inner layers

• Swap elements in groups of 4 to rotate the matrix in place

• Handle odd-sized matrices separately by adjusting the loop boundaries
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Q3. What are the page replacement algorithms in Operating Systems?
Ans. 
Page replacement algorithms are used in operating systems to decide which page to replace when a new page needs to be brought in.
• FIFO (First In, First Out) - replaces the oldest page in memory

• LRU (Least Recently Used) - replaces the page that has not been used for the longest time

• LFU (Least Frequently Used) - replaces the page that has been used the least number of times

• Optimal - replaces the page that will not be used
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Q1. It went well, results awaiting
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Explain programming languages you have experience with, explain how you would design a banking app

Behavioral test to see how you respond to different situations

Round duration - 120 minutes
Round difficulty - Hard

There was 2 parts. First part problems were based on Quantitative Aptitude. Problems were of 3 types- Easy, Medium and Hard with different scores. Difficulty keeps on increasing if you answer correctly and keeps on decreasing if you answer incorrectly.
First part was of 45 mins.
Second part consisted of 2 coding problems- Medium, Hard. One was based on Greedy and other was a difficult DP + Bitmask problem.
Coding part had more weightage than Aptitude.

Q1. 
K Centers Selection Problem
In Ninja Land, there are cities numbered from 0 to N-1. The distances between each pair of cities are represented by an N * N matrix 'DIST', where 'DIST[i][j]' is the distance ...read more
Ans. 
The problem involves selecting K cities to install servers in Ninja Land to minimize the maximum distance from any city to a nearest server.
• Iterate through all possible combinations of K cities to select for server installation.

• Calculate the maximum distance from any city to the nearest server for each combination.

• Choose the combination that minimizes the maximum distance.
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Q2. 
Beautiful String Verification
Given a non-empty string inputString, determine if it can be converted into a 'Beautiful String' using the defined operation.
You can perform any number of operations to con...read more
Ans. 
Determine if a given string can be converted into a 'Beautiful String' using a specific operation.
• Check if the input string is already a 'Beautiful String' by checking if it contains 'abc' in the correct positions.

• If 'abc' is present in the input string, check if the left and right portions satisfy the defined conditions.

• If the conditions are met, return 'True', otherwise return 'False'.
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Round duration - 90 minutes
Round difficulty - Medium

There were 3 interviewers in my panel. The most senior panellist asked q. related to my interests and internship experience.
Other 2 asked questions related to Coding and subjects. There was 1 coding question which was implementation based and involved many corner cases. They were checking if I was able to figure out different corner cases and handle those. 
There were situation based questions also asked. One question was on system design of Arogya Setu App.

Q1. 
Complex Number Multiplication
Calculate the product of two complex numbers represented as strings in the form “A+Bi”. Here, ‘A’ represents the real part, and ‘B’ represents the imaginary part.
Explanatio...read more
Ans. 
Calculate the product of two complex numbers represented as strings in the form 'A+Bi'.
• Parse the input strings to extract real and imaginary parts of both complex numbers

• Perform multiplication of the complex numbers using the formula (a+bi)*(c+di) = (ac - bd) + (ad + bc)i

• Format the result as a string in the form 'A+Bi' and return
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Round duration - 30 minutes
Round difficulty - Easy

HR round involved basic questions related to background and behaviour. It was basically a cultural fit round.

Q1. Spring boot, java 8 and microswrvices
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Q2. Basic question about spring framework
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Q1. Basic details asked about my last project that i have worked.
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Q2. Basic details about last project
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Just normal MCQ test.

Q1. SELL ABD BUY 1 array question(easy level)
Ans. 
This question involves buying and selling items in an array.
• The array must contain strings.

• You need to implement a function to buy and sell items from the array.

• Provide examples of buying and selling operations.
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Normal DP question (LC med)

Q1. Basic Java Question
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Q2. Find out Second Highest Employee Salary
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Q1. Difference between IOC and DI?
Ans. 
IOC is a design pattern where control is inverted, while DI is a technique to achieve IOC by injecting dependencies into a class.
• IOC stands for Inversion of Control, where the control of flow is inverted from the traditional top-down approach.

• DI stands for Dependency Injection, a technique used to implement IOC by injecting dependencies into a class from an external source.

• IOC is a design principle, while DI is a techn...read more
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Q2. Exception handling in the spiring Boot?
Ans. 
Exception handling in Spring Boot allows developers to gracefully handle errors and provide meaningful responses to users.
• Use @ControllerAdvice to handle exceptions globally

• Use @ExceptionHandler to handle specific exceptions

• Return custom error messages or responses to users
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Q3. @RequestBody annotation?
Ans. 
Annotation used in Spring framework to bind the HTTP request body to a method parameter.
• Used in Spring MVC to indicate that a method parameter should be bound to the body of the web request.

• Can be used with various data types like JSON, XML, etc.

• Helps in simplifying the process of handling request data in Spring applications.
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Q4. Function and BiFunction?
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Q5. Equals and Hashcode ?
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Q6. Type casting in the Java?
Ans. 
Type casting in Java is the process of converting one data type into another.
• Type casting can be done implicitly or explicitly in Java.

• Implicit type casting is done when a smaller data type is converted to a larger data type, while explicit type casting is done when a larger data type is converted to a smaller data type.

• Example of implicit type casting: int num = 10; double result = num;

• Example of explicit type casting
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Q7. Intermediate and terminal operators in Java?
Ans. 
Intermediate and terminal operators are used in Java streams to perform intermediate and terminal operations on elements.
• Intermediate operators are used to transform, filter, or manipulate elements in a stream before passing them to the next operation. Examples include map(), filter(), and sorted().

• Terminal operators are used to trigger the processing of elements in a stream and produce a result. Examples include forEa
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Q8. Functional interface in java?
Ans. 
Functional interface in Java is an interface with only one abstract method. It can have multiple default or static methods.
• Functional interfaces can be annotated with @FunctionalInterface to ensure they have only one abstract method.

• Examples of functional interfaces in Java include Runnable, Callable, and ActionListener.

• Lambda expressions can be used to implement functional interfaces concisely.
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Q9. Various methods in the RestApi?
Ans. 
Various methods in RestApi include GET, POST, PUT, DELETE.
• GET - Used to retrieve data from the server. Example: GET /users

• POST - Used to send data to the server to create a new resource. Example: POST /users

• PUT - Used to update an existing resource on the server. Example: PUT /users/1

• DELETE - Used to delete a resource on the server. Example: DELETE /users/1
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Q10. Coding question find the first non repeting char in the string using java 8.
Ans. 
Using Java 8, find the first non-repeating character in a string.
• Use Java 8 streams to convert the string to a character array.

• Use Collectors.groupingBy to group characters by count.

• Filter out characters with count > 1 and find the first character with count 1.
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Q11. Find the sum of all even numbers without using inbuild methods using stream api.
Ans. 
Sum of all even numbers without using inbuild methods using stream api
• Create an array of numbers

• Use stream to filter out even numbers

• Use stream to sum up the filtered even numbers
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