200+ Software Development Engineer II Interview Questions and Answers

I follow best software practices like unit testing, CI/CD, and Scrum to ensure quality and efficiency in my projects.

• Unit Testing: I implement unit tests using frameworks like JUnit or NUnit to ensure individual components function correctly.

• CI/CD: I use tools like Jenkins or GitHub Actions for continuous integration and deployment, automating the build and release process.

• Scrum Practices: I participate in daily stand-ups, sprint planning, and retrospectives to enhance team c...read more

Count occurrences of given element in a sorted array.

• Use binary search to find the first and last occurrence of the element.

• Subtract the indices to get the count of occurrences.

• Handle edge cases like element not present in array.

Views are virtual tables that simplify complex queries. Indexes can be created on views to improve performance.

• Views are virtual tables created by querying one or more tables.

• They simplify complex queries by storing the query logic in the view.

• Indexes can be created on views to improve query performance.

• Indexes on views can speed up data retrieval by allowing the database to quickly locate the relevant data.

Find the maximum length of a subarray with almost 2 distinct elements.

• Use a sliding window approach to keep track of the count of distinct elements in the subarray.

• Update the window size based on the number of distinct elements in the subarray.

• Keep track of the maximum length encountered so far.

Plan ETL for various data sources by identifying sources, defining data extraction methods, transforming data, and loading into target systems.

• Identify all data sources and understand their structure and format

• Define data extraction methods based on the source systems (e.g. APIs, databases, files)

• Transform data as needed to match the target system's schema and requirements

• Consider data quality issues and implement data cleansing processes

• Load the transformed data into the tar...read more

Horizontal scaling is adding more machines to your pool of resources, while vertical scaling is adding more power (CPU, RAM) to an existing machine.

• Use horizontal scaling when you need to increase capacity by adding more machines to distribute the load.

• Use vertical scaling when you need to handle increased load on a single machine by adding more resources like CPU or RAM.

• Horizontal scaling is more cost-effective and provides better fault tolerance.

• Vertical scaling is easier t...read more

Design a chat room system where users can chat with each other and join chat rooms.

• Implement user authentication and authorization to ensure secure access to chat rooms.

• Create a database to store chat messages, user information, and chat room details.

• Develop a real-time messaging system using websockets for instant communication.

• Allow users to create new chat rooms and join existing ones.

• Include features like message history, notifications, and user profiles.

Libraries provide pre-written code for common tasks, while polyfills fill in missing browser functionality.

• Libraries save time by providing pre-written code for common tasks

• Polyfills fill in missing browser functionality for older browsers

• Libraries can improve code readability and maintainability

• Polyfills can help ensure consistent behavior across different browsers

• Using libraries and polyfills can help developers focus on higher-level logic rather than low-level implementati...read more

Design SkipTracker() for Amazon Prime Music

• SkipTracker() should keep track of skipped songs in Amazon Prime Music

• It should maintain a list of skipped songs as an array of strings

• The list should be updated whenever a song is skipped

• SkipTracker() should provide methods to add, remove, and retrieve skipped songs

Clustered index physically reorders the data in the table, unclustered index does not, unique index enforces uniqueness of values.

• Clustered index physically reorders the data in the table based on the index key. Only one clustered index per table.

• Unclustered index does not reorder the data in the table. Can have multiple unclustered indexes per table.

• Unique index enforces uniqueness of values in the indexed column(s). Can be clustered or unclustered.

Best practices for implementing microservices include modular design, independent deployment, and robust communication strategies.

• Design for failure: Implement circuit breakers to handle service outages gracefully.

• Use API gateways: Centralize requests and manage authentication, logging, and routing.

• Decentralize data management: Each microservice should manage its own database to avoid tight coupling.

• Implement service discovery: Use tools like Consul or Eureka to allow service...read more

Spring Boot simplifies Java application development by providing a framework for building stand-alone, production-ready applications.

• Convention over configuration: Reduces the need for extensive configuration files.

• Embedded servers: Supports embedded servers like Tomcat and Jetty for easy deployment.

• Microservices support: Ideal for building microservices architectures with minimal setup.

• Auto-configuration: Automatically configures Spring applications based on dependencies pre...read more

Find max length of substring with equal 1s and 0s in a binary string.

• Use a hash table to store the difference between the count of 1s and 0s seen so far.

• If the difference is 0, update the max length seen so far.

• If the difference is already in the hash table, update the max length using the current index and the index where the difference was first seen.

• Return the max length.

• Example: '1100010110' -> 8

Design a REST API for managing a library system with books, authors, and users.

• Define endpoints: GET /books, POST /books, GET /books/{id}, PUT /books/{id}, DELETE /books/{id}.

• Use JSON format for request and response bodies.

• Implement authentication for user actions (e.g., borrowing books).

• Consider pagination for GET /books to handle large datasets.

• Use appropriate HTTP status codes (e.g., 200 OK, 404 Not Found, 201 Created).

Temp table is local to a session, global table is accessible across sessions, variable table is a table variable declared in a function or stored procedure.

• Temp table is created and dropped automatically when the session ends.

• Global table is created using a double hash (##) prefix and is accessible across sessions.

• Variable table is a table variable declared in a function or stored procedure and is only accessible within that scope.

Decode a string by expanding integers to repeat characters within brackets.

• Iterate through the string character by character

• If a digit is encountered, keep track of the number

• When encountering '[', push the current result and number onto the stack

• When encountering ']', repeat the substring inside brackets based on the number on top of the stack

• Continue until the entire string is decoded

Given a number x, find the minimum number of operations (decrement by 1 or multiply by 2) to convert it to y.

• Use a breadth-first search (BFS) approach to explore all possible operations and find the minimum number of steps.

• Start with x and generate all possible next numbers by decrementing or multiplying by 2.

• Keep track of the number of steps taken to reach each number and stop when y is found.

• Use a queue to implement the BFS algorithm.

• Example: x = 10, y = 30. Possible steps:...read more

Streams in Java8 offer concise and readable code for processing collections compared to traditional for loops.

• Streams provide functional-style operations like map, filter, and reduce for easy data processing.

• Streams allow for parallel processing of data, potentially improving performance.

• Streams promote immutability and encourage writing more declarative code.

• Streams reduce boilerplate code and make the code more readable and maintainable.

• Example: Using streams to filter a li...read more

Interface is a contract with no implementation, while abstract class can have some implementation.

• Interface can only have abstract methods, while abstract class can have both abstract and non-abstract methods.

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

• Interfaces are used to achieve multiple inheritance in Java.

• Abstract classes can have constructors, while interfaces cannot.

• Example: Interface - Runnable, Abstract class - Animal with abstr...read more

Given a binary tree, find the path with the largest sum of node values.

• Use depth-first search to traverse the tree and keep track of the current path sum.

• At each node, compare the current path sum with the maximum path sum seen so far.

• Return the path with the maximum sum.

• If the tree is empty, return an empty path.

Find the first k most occurring strings from a given list

• Use a hashmap to store the frequency of each string

• Sort the hashmap based on frequency in descending order

• Return the first k keys from the sorted hashmap

Implement an in-memory backend for a social media app in 90 mins

• Use a HashMap to store user profiles and posts

• Implement methods for CRUD operations on user profiles and posts

• Consider implementing data structures like LinkedList or PriorityQueue for managing posts in chronological order

Implement timer in React using useTimeout and disable it after unmounting

• Use useState to store the timer ID

• Use useEffect to start the timer on component mount and clear it on unmount

• Use clearTimeout to disable the timer when the component unmounts

I tackled a complex issue with performance optimization in a large-scale React application, enhancing user experience significantly.

• Identified performance bottlenecks using React Profiler and Chrome DevTools.

• Implemented code-splitting with React.lazy and Suspense to reduce initial load time.

• Optimized component re-renders by using React.memo and useCallback hooks.

• Reduced bundle size by analyzing dependencies and removing unused libraries.

• Conducted A/B testing to measure the im...read more

Implement merge sort algorithm to sort array of strings based on a given key

• Divide the array into two halves recursively

• Merge the two sorted halves based on the given key

• Repeat until the entire array is sorted

• Example: ['apple', 'banana', 'cherry'] sorted based on length: ['apple', 'cherry', 'banana']

Implement binary search to find the number in a sorted array with lowest code complexity.

• Use binary search algorithm to efficiently find the number in the sorted array.

• Compare the target number with the middle element of the array and adjust the search range accordingly.

• Repeat the process until the target number is found or the search range is exhausted.

Determining job scheduling order based on dependencies

• Create a directed graph with jobs as nodes and dependencies as edges

• Use topological sorting to determine the order of scheduling

• If there is a cycle in the graph, it is not possible to schedule the jobs

• Consider using depth-first search to traverse the graph