McKinsey & Company Senior Software Engineer Interview Questions and Answers

Promise.all vs promise.allsettled how to resolve asynchronus call using promises

Q1. Salary negotiation
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Q2. Education gap between studies
Ans. 
Addressing any gaps in education during the interview process.
• Acknowledge any gaps in education and explain how you have worked to overcome them

• Highlight any additional courses, certifications, or self-study you have done to fill in the gaps

• Discuss how you have applied your knowledge in real-world projects to compensate for any educational shortcomings
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Q1. SSRS reports - Why temp tables are used and not regular tables?
Ans. 
Temp tables are used in SSRS reports for performance optimization and to reduce resource consumption.
• Temp tables are used to store intermediate results during report generation, reducing the need to repeatedly query the database.

• Regular tables can lead to locking and contention issues in multi-user environments, while temp tables are session-specific and do not cause conflicts.

• Temp tables can be indexed and optimized f...read more
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Q2. Table group and cache look-up
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Q1. Infra architechture
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Q2. Form patterns - D365FO
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Q1. Why are you looking for job change?
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This round is purely based on DS /Algo and System Design and their real-life applications implications and a few case studies.

Q1. How memory is managed in python?
Ans. 
Python uses automatic memory management through garbage collection.
• Python uses reference counting to keep track of memory usage.

• When an object's reference count reaches zero, it is deleted.

• Python also uses a garbage collector to clean up circular references.

• Memory allocation is handled by the Python memory manager.

• Python provides tools like sys.getsizeof() to monitor memory usage.
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Q2. Three-tier architecture, Flask, Docker, Redis,Microservice,Design Patterns
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Q1. Aptitude-based and technical situation questions with senior members of the team.
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Q1. Why are you looking for a change?
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Q2. Where do you see yourself in 5 years?
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Basic coding questions and SQL queries

Q1. Technology used
Ans. 
Various technologies including Java, Python, SQL, AWS, Docker, Kubernetes, etc.
• Java

• Python

• SQL

• AWS

• Docker

• Kubernetes
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1 hr test with questions on react and , js, python

Q1. Difference between inheritance and polymorphism
Ans. 
Inheritance is a way to create a new class using properties and methods of an existing class, while polymorphism allows objects of different classes to be treated as objects of a common superclass.
• Inheritance allows a class to inherit properties and methods from another class.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• Inheritance promotes code reusability and reduce...read more
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Q2. Write a code to check anagram or not
Ans. 
Code to check if two strings are anagrams
• Create a function that takes in two strings as input

• Convert both strings to lowercase and remove any spaces

• Sort both strings and compare if they are equal to determine if they are anagrams
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Round duration - 60 Minutes
Round difficulty - Medium

This round started slow with some basic fundamental questions around OOPS and then paced up higher to some more advanced questions Java and Multithreading in Java in general.

Q1. Can you explain the SOLID principles in Object Oriented Design?
Ans. 
SOLID principles are a set of five design principles in object-oriented programming to make software more maintainable, flexible, and scalable.
• Single Responsibility Principle (SRP) - A class should have only one reason to change.

• Open/Closed Principle (OCP) - Software entities should be open for extension but closed for modification.

• Liskov Substitution Principle (LSP) - Objects of a superclass should be replaceable with...read more
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Q2. What is abstraction in Object-Oriented Programming?
Ans. 
Abstraction in OOP is the concept of hiding complex implementation details and showing only the necessary features to the outside world.
• Abstraction allows us to focus on what an object does instead of how it does it

• It helps in reducing complexity and improving maintainability of code

• Example: In a car, we don't need to know the internal workings of the engine to drive it
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Q3. How is an abstract class different from an interface?
Ans. 
Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have constructors, fields, and methods with implementation.

• Interface can only have abstract methods and constants.

• A class can implement multiple interfaces but can only inherit from one abstract class.

• Example: Abstract class - Animal with abstract method 'eat', Interface - Flyable with metho...read more
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Q4. What is a classloader in Java?
Ans. 
A classloader in Java is a part of the Java Runtime Environment that dynamically loads Java classes into the Java Virtual Machine.
• Classloaders are responsible for loading classes at runtime based on the fully qualified name of the class.

• There are different types of classloaders in Java such as Bootstrap Classloader, Extension Classloader, and Application Classloader.

• Classloaders follow a delegation model where a classl...read more
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Q5. Why is Java considered platform independent, while the Java Virtual Machine (JVM) is platform dependent?
Ans. 
Java is platform independent because it compiles code into bytecode that can run on any system with a JVM, which is platform dependent.
• Java code is compiled into bytecode, which is platform independent

• The JVM interprets the bytecode and translates it into machine code specific to the underlying platform

• This allows Java programs to run on any system with a JVM installed, making Java platform independent
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Q6. Can you tell us something about the JIT compiler?
Ans. 
JIT compiler stands for Just-In-Time compiler, which dynamically compiles and optimizes code during runtime.
• JIT compiler is used to improve the performance of applications by compiling code at runtime instead of ahead of time.

• It converts bytecode into native machine code on-the-fly, allowing for faster execution.

• Examples of JIT compilers include HotSpot for Java and V8 for JavaScript.
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Q7. Can you explain what a thread pool is?
Ans. 
A thread pool is a collection of worker threads that are used to execute tasks concurrently.
• Thread pools help manage and reuse threads to improve performance and reduce overhead.

• They limit the number of concurrent threads to prevent resource exhaustion.

• Tasks are submitted to the pool and executed by available threads.

• Example: Java's Executor framework provides implementations of thread pools like ThreadPoolExecutor.
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Q8. What is the difference between the interrupted() and isInterrupted() methods in Java?
Ans. 
interrupted() checks if the current thread has been interrupted, while isInterrupted() checks if a thread has been interrupted.
• interrupted() is a static method in the Thread class, while isInterrupted() is an instance method.

• interrupted() clears the interrupted status of the current thread, while isInterrupted() does not.

• Example: Thread.currentThread().interrupt(); System.out.println(Thread.interrupted()); // prints tr...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round primarily focused on some major concepts in Spring Boot and Hibernate and had questions revolving around
that with some more questions from Microserviices and Java Design Patterns.

Q1. How many bean scopes are supported by Spring?
Ans. 
Spring supports five bean scopes: singleton, prototype, request, session, and application.
• Singleton scope creates a single instance per Spring IoC container.

• Prototype scope creates a new instance every time the bean is requested.

• Request scope creates a new instance for each HTTP request.

• Session scope creates a single instance per HTTP session.

• Application scope creates a single instance per ServletContext.
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Q2. What do you understand by autowiring in Spring Boot, and can you name the different modes of autowiring?
Ans. 
Autowiring in Spring Boot is a way to automatically inject dependencies into a Spring bean.
• Autowiring is a feature in Spring that allows the container to automatically inject the dependencies of a bean.

• There are different modes of autowiring in Spring: 'byName', 'byType', 'constructor', 'autodetect', and 'no'.

• For example, in 'byName' autowiring, Spring looks for a bean with the same name as the property being autowired...read more
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Q3. Can you explain the @RestController annotation in Spring Boot?
Ans. 
The @RestController annotation in Spring Boot is used to define a class as a RESTful controller.
• Used to create RESTful web services in Spring Boot

• Combines @Controller and @ResponseBody annotations

• Eliminates the need to annotate each method with @ResponseBody
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Q4. What does the @SpringBootApplication annotation do internally?
Ans. 
The @SpringBootApplication annotation is used to mark the main class of a Spring Boot application.
• It is a combination of @Configuration, @EnableAutoConfiguration, and @ComponentScan annotations.

• It tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings.

• It also implicitly provides a base package for component scanning.

• Example: @SpringBootApplication

• Example: @Spring...read more
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Q5. Can you explain Spring Actuator and its advantages?
Ans. 
Spring Actuator is a set of production-ready features to help monitor and manage your application.
• Provides insights into application's health, metrics, and other useful information

• Enables monitoring and managing of application through HTTP endpoints

• Can be used to check application's health, view metrics, and even perform custom actions

• Helps in identifying and troubleshooting issues in production environment
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Q6. What are the concurrency strategies available in Hibernate?
Ans. 
Hibernate provides various concurrency strategies like optimistic locking, pessimistic locking, and versioning.
• Optimistic locking: Allows multiple transactions to read a row simultaneously, but only one can update it at a time. Uses versioning or timestamp to check for conflicts.

• Pessimistic locking: Locks the row for exclusive use by one transaction, preventing other transactions from accessing it until the lock is rel...read more
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Q7. Can you explain the working of Microservice Architecture?
Ans. 
Microservice architecture is an architectural style that structures an application as a collection of loosely coupled services.
• Microservices are small, independent services that work together to form a complete application.

• Each microservice is responsible for a specific business function and can be developed, deployed, and scaled independently.

• Communication between microservices is typically done through APIs.

• Microserv...read more
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Q8. What issues are generally addressed by Spring Cloud?
Ans. 
Spring Cloud addresses issues related to building and deploying cloud-native applications.
• Service discovery and registration

• Load balancing

• Circuit breakers

• Distributed configuration management

• Routing and gateway

• Monitoring and tracing
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Q9. Can you explain the Singleton design pattern?
Ans. 
Singleton design pattern ensures a class has only one instance and provides a global point of access to it.
• Ensures a class has only one instance by providing a global access point to it

• Uses a private constructor to restrict instantiation of the class

• Provides a static method to access the single instance
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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. Why should we hire you?
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Q2. Why are you looking for a job change?
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