100+ Software Engineer III Interview Questions and Answers

Find the longest substring in a string without repeating characters.

• Use a sliding window approach to iterate through the string.

• Keep track of the characters seen so far in a set.

• Update the start of the window when a repeating character is encountered.

• Calculate the length of the current substring and update the longest substring found.

• Repeat until the end of the string is reached.

Microservices in Java are a way to design software applications as a collection of small, loosely coupled services.

• Microservices architecture breaks down a large application into smaller, independent services that can be developed, deployed, and scaled independently.

• Each microservice typically focuses on a specific business function and communicates with other services through APIs.

• Java is a popular language for implementing microservices due to its strong ecosystem, librarie...read more

Scaling the application involves optimizing performance, increasing capacity, and ensuring reliability.

• Implementing load balancing to distribute traffic evenly across multiple servers

• Using caching mechanisms to reduce database load and improve response times

• Utilizing horizontal scaling by adding more servers to handle increased traffic

• Optimizing database queries and indexes for faster data retrieval

• Implementing microservices architecture to break down the application into sma...read more

Recursively find the height of a binary tree by comparing the heights of left and right subtrees.

• Start by checking if the root is null, return -1 if so.

• Recursively find the height of the left subtree and right subtree.

• Return the maximum of the heights of the left and right subtrees, plus 1 for the current node.

Count the number of distinct islands in a tree with 0's and 1's where joined 1's form an island.

• Traverse the tree and identify connected components of 1's to form islands.

• Use a set to store the unique shapes of islands to avoid counting duplicates.

• Consider different shapes of islands like horizontal, vertical, diagonal, etc.

• Example: [['1', '0', '1'], ['1', '1', '0']] has 2 distinct islands.

Design a chatbot that supports both 1-1 and group chats

• Implement a user authentication system to differentiate between 1-1 and group chats

• Create separate chat rooms for group chats where multiple users can join

• Include features like message notifications, file sharing, and message search functionality

• Utilize natural language processing to understand and respond to user messages

• Allow users to customize their chatbot settings and preferences

The get and put methods of Java HashMap are used to retrieve and store key-value pairs respectively.

• To retrieve a value from a HashMap, use the get() method and pass the key as a parameter.

• To store a key-value pair in a HashMap, use the put() method and pass the key and value as parameters.

• Example: HashMap map = new HashMap<>(); map.put("apple", 5); int count = map.get("apple"); // returns 5

Find the largest subsequence in a given string.

• Iterate through the string and keep track of the current subsequence length

• Update the length when encountering a character that is greater than the previous character

• Return the longest subsequence found

I have experience in designing and implementing scalable systems for various projects.

• Designed and implemented a microservices-based architecture for a healthcare platform

• Developed a distributed system for real-time data processing using Apache Kafka and Spark

• Optimized database schema and queries for a high-traffic e-commerce website

• Implemented caching and load balancing strategies for a social media platform

• Designed and developed a RESTful API for a mobile application

The program checks if a given string is a palindrome or not.

• Create a function that takes a string as input

• Reverse the string and compare it with the original string

• Return true if they are the same, false otherwise

Angular Dependency Injection is a design pattern in Angular where objects are passed to a class instead of the class creating them.

• Angular Dependency Injection allows for easier testing and reusability of code.

• It helps in decoupling components and services in Angular applications.

• Dependencies are provided at the root level or at component level using providers array in @NgModule or @Component decorator.

• Example: @Injectable() decorator is used to define a service that can be i...read more

Global variables are accessible throughout the program, while static variables are limited to the scope in which they are defined.

• Global variables are declared outside of any function and can be accessed by any function in the program.

• Static variables are declared within a function and retain their value between function calls.

• Example: int globalVar = 10; static int staticVar = 5;

• Example: Global variable can be accessed in multiple functions, while static variable retains its...read more

Count the number of alternate substrings in a given string.

• Iterate through the string and check for alternating characters.

• Keep track of the count of alternate substrings found.

• Return the total count of alternate substrings.

Familiarity with different Azure services is essential for a Software Engineer III role.

• Understanding of Azure Virtual Machines for scalable computing

• Knowledge of Azure Blob Storage for storing large amounts of unstructured data

• Experience with Azure Functions for serverless computing

• Familiarity with Azure SQL Database for relational database management

• Understanding of Azure Cognitive Services for AI and machine learning capabilities

Microservices architecture using Docker containers and Kubernetes for scalability and flexibility.

• Utilizing microservices to break down the application into smaller, independent services

• Using Docker containers for easy deployment and scalability

• Leveraging Kubernetes for orchestration and management of containers

Some of the new features in .Net 7 include performance improvements, new language features, and enhanced tooling.

• Performance improvements such as faster startup times and reduced memory usage

• New language features like records, top-level statements, and pattern matching enhancements

• Enhanced tooling with improved support for Visual Studio and Visual Studio Code

• Support for ARM64 architecture and WebAssembly

• Improved support for cloud-native applications and microservices

Detecting cycle in a linked list and discussing behavioral aspects

• Explain how to use Floyd's Tortoise and Hare algorithm to detect a cycle in a linked list

• Discuss the importance of understanding memory management in linked lists to prevent cycles

• Explain the impact of cycles in linked lists on time complexity and space complexity of algorithms

A date picker in JavaScript allows users to select a date from a calendar interface.

• Use HTML input element with type 'date' for modern browsers

• For older browsers, use a JavaScript library like jQuery UI Datepicker

• Implement validation to ensure selected date is within acceptable range

To get the right and left view of a binary tree, perform a level order traversal and keep track of the first node encountered at each level.

• Perform a level order traversal of the binary tree

• Keep track of the first node encountered at each level for both left and right views

• Store the first node encountered at each level in separate arrays for left and right views

Find the maximum ZigZag length in a tree.

• Perform a depth-first search (DFS) on the tree to traverse all nodes.

• Keep track of the maximum ZigZag length encountered during traversal.

• At each node, calculate the ZigZag length by comparing the depths of the left and right children.

• Update the maximum ZigZag length if the current ZigZag length is greater.

Finding patterns in a stream of numbers involves analyzing the sequence for recurring trends or relationships.

• Look for repeating sequences or intervals in the numbers.

• Check for arithmetic progressions or geometric progressions.

• Consider using algorithms like sliding window or dynamic programming for efficient pattern detection.

Merge sort implemented in a linked list

• Divide the linked list into two halves using slow and fast pointers

• Recursively sort each half

• Merge the sorted halves back together

I have experience in system design and currently work as a Software Engineer III.

• I have designed scalable systems using microservices architecture.

• I have implemented caching mechanisms to improve system performance.

• I have worked on optimizing database queries for faster data retrieval.

• I have experience in designing RESTful APIs for communication between different services.

Sort an array of 0s, 1s, and 2s and find the left view of a binary tree.

• To sort the array of 0s, 1s, and 2s, you can use the Dutch National Flag algorithm which sorts the array in a single pass.

• To find the left view of a binary tree, perform a level order traversal and keep track of the first node at each level.

Join is used to combine rows from two or more tables based on a related column, while subquery is a query nested within another query.

• Join is used to retrieve data from multiple tables based on a related column

• Subquery is a query nested within another query

• Join is typically more efficient than subqueries for large datasets

• Example: SELECT * FROM table1 JOIN table2 ON table1.id = table2.id

• Example: SELECT * FROM table WHERE id IN (SELECT id FROM another_table)

LLD for a S3 or a storage based system involves designing the detailed architecture and components of the system.

• Define the data model including objects, metadata, and storage classes

• Design the system components like storage nodes, metadata servers, and access control mechanisms

• Consider scalability, fault tolerance, and data consistency in the design

• Implement features like versioning, encryption, and access control policies

• Optimize for performance and cost efficiency

High Level Design (HLD) for a commerce application involves designing the overall architecture and components of the application.

• Identify key components such as user interface, database, payment gateway, product catalog, and order processing.

• Define the interactions between components and how data flows through the system.

• Consider scalability, security, and performance requirements.

• Use technologies like microservices architecture, RESTful APIs, and cloud services.

• Example: Use ...read more

Solid Principles are a set of five design principles for writing maintainable and scalable software.

• Single Responsibility Principle (SRP)

• Open/Closed Principle (OCP)

• Liskov Substitution Principle (LSP)

• Interface Segregation Principle (ISP)

• Dependency Inversion Principle (DIP)

Low level design for a ride-sharing service like Ola or Uber

• User requests a ride through the app

• App calculates fare based on distance and time

• Driver accepts the ride request

• GPS tracking for real-time location updates

• Payment processing through the app

HashMap is implemented using an array of linked lists to store key-value pairs.

• HashMap consists of an array of buckets, each containing a linked list of key-value pairs.

• Hashing function is used to determine the index of the bucket where a key-value pair will be stored.

• Collision resolution techniques like chaining or open addressing are used to handle collisions.

• HashMap allows null keys and values, but only one null key.

• Example: HashMap map = new HashMap<>();

OYO Rooms system design involves creating a platform for booking budget accommodations with standardized amenities.

• Implement user-friendly interface for searching and booking rooms

• Develop a robust backend system for managing bookings, payments, and room availability

• Utilize data analytics to optimize pricing and room allocation

• Integrate with third-party services for reviews, location mapping, and payment gateways

LLD for a storage based system involves designing the detailed architecture and components of the system to efficiently store and retrieve data.

• Identify the requirements for the storage system, including data types, volume, access patterns, and performance expectations.

• Design the data storage architecture, including data structures, indexing mechanisms, and storage technologies like databases or file systems.

• Define the data access and retrieval mechanisms, such as APIs, proto...read more

Determining the level of water between buildings based on various factors

• Consider the elevation of each building

• Take into account the distance between the buildings

• Factor in any natural or man-made barriers that may affect water flow

Find the maximum length of increasing subsequence in an array of strings.

• Use dynamic programming to keep track of the length of increasing subsequences ending at each index.

• Iterate through the array and update the length of increasing subsequences.

• Return the maximum length found.

Design patterns in Java are reusable solutions to common problems in software design.

• Design patterns help in creating maintainable and scalable code.

• Examples include Singleton, Factory, Observer, Strategy, and Decorator patterns.

• Each design pattern has its own purpose and implementation details.

• Design patterns promote code reusability and flexibility in software development.

Design a scalable system like Instagram for sharing photos and videos

• Use a distributed architecture with multiple servers for handling user uploads, storage, and retrieval

• Implement a content delivery network (CDN) for fast delivery of media content to users worldwide

• Utilize a database system for storing user data, media metadata, and relationships between users and content

• Incorporate caching mechanisms to improve performance and reduce load on the database

• Implement a notifica...read more

Lifetime scopes in .Net refer to the lifespan of objects managed by a dependency injection container.

• Lifetime scopes define how long an object should exist within the container

• Common lifetime scopes include transient, singleton, scoped

• Transient objects are created each time they are requested

• Singleton objects are created once and reused for the lifetime of the application

• Scoped objects are created once per request or scope

Single sign-on (SSO) is a process that allows users to access multiple applications with a single set of login credentials.

• SSO eliminates the need for users to remember multiple usernames and passwords.

• It improves security by reducing the risk of password-related security breaches.

• SSO can be implemented using various protocols such as SAML, OAuth, and OpenID Connect.

• Examples of SSO providers include Okta, OneLogin, and Microsoft Azure AD.

SAML is a protocol used for exchanging authentication and authorization data between parties.

• SAML stands for Security Assertion Markup Language.

• It is used for single sign-on (SSO) authentication.

• SAML has three main components: the identity provider (IDP), the service provider (SP), and the user.

• The SAML process involves the user requesting access to a service, the SP redirecting the user to the IDP for authentication, the IDP authenticating the user and generating a SAML asse...read more

PropTypes are a way to type-check props in React components to ensure they are passed correctly.

• Used in React to specify the data type of props passed to a component

• Helps catch bugs by providing warnings if incorrect data types are passed

• Can be defined using PropTypes library or as static properties in a component

The High-Level Design (HLD) of an order processing system involves outlining the overall architecture and components of the system.

• Identify the main components of the system such as order creation, order validation, order fulfillment, and order tracking.

• Define the interactions between these components and how data flows between them.

• Consider scalability, fault tolerance, and performance requirements in the design.

• Include details on data storage, processing logic, and external...read more

Multithreading in Java allows multiple threads to execute concurrently, improving performance and responsiveness.

• Multithreading in Java is achieved by extending the Thread class or implementing the Runnable interface.

• Threads share the same memory space, so synchronization is important to prevent data corruption.

• Java provides synchronized keyword, locks, and concurrent data structures for thread safety.

• Example: Creating a new thread - Thread thread = new Thread(new MyRunnable(...read more

Remove leaf nodes of a tree

• Traverse the tree in postorder fashion

• For each node, check if it is a leaf node (both children are null)

• If it is a leaf node, remove it by setting its parent's reference to null

Train water trapping problem involves calculating the amount of water that can be trapped between blocks.

• Calculate the maximum height of blocks on left and right of each block

• Find the minimum of the two heights and subtract the height of the current block to get trapped water

• Sum up the trapped water for all blocks to get total trapped water

Cycle detection in graph involves detecting if there is a cycle present in a graph data structure.

• Use Depth First Search (DFS) or Breadth First Search (BFS) to detect cycles in a graph.

• Maintain a visited set to keep track of visited nodes and a recursion stack to keep track of nodes in the current path.

• If a node is visited again and is in the recursion stack, then a cycle is detected.

• Example: Detecting a cycle in a directed graph using DFS.

A note taking app that allows users to create, edit, and organize their notes.

• Implement a user interface for creating and editing notes

• Include features like text formatting, image attachments, and voice recordings

• Provide options for organizing notes into folders or categories

• Include search functionality to easily find specific notes

• Implement synchronization across devices for seamless access to notes

Create a timer in React using useState and useEffect hooks

• Use useState hook to store the timer value

• Use useEffect hook to update the timer value every second

• Display the timer value in the component's render method