Bajaj Finserv Android Developer Interview Questions and Answers

Q1. Design patterns that you have followed in your past projects.
Ans. 
I have followed the MVC, Singleton, and Factory design patterns in my past projects.
• MVC pattern for separating concerns and improving maintainability

• Singleton pattern for ensuring only one instance of a class is created

• Factory pattern for creating objects without exposing the instantiation logic
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Q2. How to secure the applications?
Ans. 
Applications can be secured by implementing various security measures such as authentication, authorization, encryption, and regular updates.
• Implement strong authentication mechanisms such as multi-factor authentication

• Use authorization to restrict access to sensitive data and functionalities

• Encrypt sensitive data both in transit and at rest

• Regularly update the application and its dependencies to patch security vulnera...read more
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Q1. 1)Project related,
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Q2. What is the Polymorphism?
Ans. 
Polymorphism is the ability of a function or method to behave differently based on the object it is acting upon.
• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example: Inheritance in object-oriented programming languages like Java allows for polymorphism.
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Q3. What is RestController?
Ans. 
RestController is a class in Spring framework used to handle HTTP requests and return responses as JSON or XML.
• Handles HTTP requests in Spring framework

• Returns responses as JSON or XML

• Annotate a class with @RestController to define it as a RestController

• Example: @RestController public class UserController {}
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Find the number of occurrences of each element in the given ArrayList

Q1. Discussion with hr like reason to switch.
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Round duration - 65 Minutes
Round difficulty - Medium

This was an online proctured coding test where we had 2 questions to solve under 65 minutes. Both the questions were of difficulty Medium to Hard.

Q1. 
Make Array Elements Equal Problem Statement
Given an integer array, your objective is to change all elements to the same value, minimizing the cost. The cost of changing an element from x to y is defined ...read more
Ans. 
Find the minimum cost to make all elements of an array equal by changing them to a common value.
• Calculate the median of the array and find the sum of absolute differences between each element and the median.

• Sort the array and find the median element, then calculate the sum of absolute differences between each element and the median.

• If the array has an even number of elements, consider the average of the two middle elem
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Q2. 
Pattern Matching Problem Statement
Given a pattern as a string and a set of words, determine if the pattern and the words list align in the same sequence.
Input:
T (number of test cases)
For each test ca...read more
Ans. 
Given a pattern and a list of words, determine if the words align with the pattern.
• Create a mapping between characters in the pattern and words in the list.

• Check if the mapping preserves the order of characters in the pattern.

• Return 'True' if the sequence of words matches the order of characters in the pattern, else return 'False'.
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Round duration - 50 Minutes
Round difficulty - Medium

This round had 2 algorithmic questions in which I first had to explain my approach with proper complexity analysis and then code the solution in any preferred IDE.

Q1. 
Pair Sum Problem Statement
You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.
Note:
...read more
Ans. 
Find pairs of elements in an array that sum up to a given value, sorted in a specific order.
• Iterate through the array and for each element, check if the complement (S - current element) exists in a hash set.

• If the complement exists, add the pair to the result list.

• Sort the result list based on the criteria mentioned in the question.

• Return the sorted list of pairs.
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Q2. 
Merge Overlapping Intervals Problem Statement
Given a specified number of intervals, where each interval is represented by two integers denoting its boundaries, the task is to merge all overlapping interv...read more
Ans. 
Merge overlapping intervals and return sorted list of merged intervals.
• Iterate through intervals and merge overlapping ones

• Sort merged intervals based on starting times

• Handle edge cases like empty input or single interval

• Example: Input - [[1,4], [3,5], [6,8], [10,12], [8,9]], Output - [[1,5], [6,9], [10,12]]
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 1 standard coding question followed by some questions from OS and at last I was also asked some questions related to Statistics and Probability.

Q1. 
Spiral Matrix Problem Statement
You are given a N x M matrix of integers. Your task is to return the spiral path of the matrix elements.
Input
The first line contains an integer 'T' which denotes the nu...read more
Ans. 
The task is to return the spiral path of elements in a given matrix.
• Iterate through the matrix in a spiral path by adjusting the boundaries at each step.

• Keep track of the direction of traversal (right, down, left, up) to cover all elements.

• Handle edge cases such as when the matrix is a single row or column.

• Implement the spiral path traversal algorithm efficiently to meet the time limit.

• Ensure to print the elements in t
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Q2. How can you print numbers from 1 to 100 using more than two threads in an optimized approach?
Ans. 
Use multiple threads to print numbers from 1 to 100 in an optimized approach.
• Divide the range of numbers (1-100) among the threads to avoid overlap.

• Use synchronization mechanisms like mutex or semaphore to ensure orderly printing.

• Consider using a shared variable to keep track of the current number being printed.
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Q3. What is meant by multitasking and multithreading in operating systems?
Ans. 
Multitasking refers to the ability of an operating system to run multiple tasks concurrently, while multithreading involves executing multiple threads within a single process.
• Multitasking allows multiple processes to run simultaneously on a single processor, switching between them quickly.

• Multithreading enables a single process to execute multiple threads concurrently, sharing resources like memory and CPU time.

• Multita...read more
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Round duration - 30 Minutes
Round difficulty - Easy

This is a cultural fitment testing round .HR was very frank and asked standard questions. Then we discussed about my role.

Q1. What do you know about the company?
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Q2. Why should we hire you?
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Simple to intermediate coding questions

Q1. Based on resume and related to job description
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Q1. Basic HR questions
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Q1. Discuss about your current project
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Q2. Questions related to current project
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Q3. How to monitor heap memory area? And how objects are removed from heap memory
Ans. 
Heap memory can be monitored using tools like profilers. Objects are removed from heap memory through garbage collection.
• Use profilers like VisualVM or Java Mission Control to monitor heap memory usage

• Analyze heap dumps to identify memory leaks and optimize memory usage

• Garbage collection automatically removes unreferenced objects from heap memory

• Different garbage collection algorithms like Mark and Sweep, Copying, and ...read more
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Q4. How to handle an application running on different instances?
Ans. 
Handling an application running on different instances involves load balancing, monitoring, and synchronization.
• Implement load balancing to distribute the workload evenly across instances.

• Monitor the performance and health of each instance to ensure optimal operation.

• Use synchronization techniques to maintain consistency and avoid conflicts between instances.

• Implement failover mechanisms to handle instances going offli...read more
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Q5. Can you design a load balancer which can handle multiple addition of new instances or pods?
Ans. 
Yes, a load balancer can handle multiple addition of new instances or pods.
• A load balancer distributes incoming traffic across multiple instances or pods.

• To handle multiple additions, the load balancer should be able to dynamically update its routing configuration.

• Load balancers can use various algorithms to distribute traffic, such as round-robin, least connections, or weighted distribution.

• Load balancers can also per...read more
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Q6. How to implements caching in your application?
Ans. 
Caching improves application performance by storing frequently accessed data in memory.
• Identify the data that needs to be cached

• Choose a caching strategy (e.g., in-memory cache, distributed cache)

• Implement caching logic in the application code

• Set appropriate cache expiration policies

• Handle cache invalidation when data changes
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Q1. Can you design a distributed system which can handle load of 1M requests per second?
Ans. 
Yes, a distributed system can handle 1M requests per second by using load balancing, horizontal scaling, and caching.
• Implement load balancing to distribute incoming requests across multiple servers.

• Use horizontal scaling by adding more servers to handle the increased load.

• Implement caching to store frequently accessed data and reduce the load on the backend.

• Optimize the system by using efficient algorithms and data str...read more
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