50+ Software Development Engineer 3 Interview Questions and Answers

Triggers are database objects that execute automatically in response to certain events. Mutating trigger problem occurs when a trigger tries to read or modify a table that is already being modified by the same transaction.

• Triggers can be used to enforce business rules, audit changes, and maintain referential integrity.

• They can be used to automatically update a table when a related table is updated.

• Mutating trigger problem can be solved by using compound triggers, which allow ...read more

Finding overlapping intervals for calculating final payment of store worker

• Identify all the intervals for which the worker is eligible for payment

• Check for overlapping intervals and merge them

• Calculate the final payment based on the merged intervals

Defining and using a parameterized cursor in PL/SQL

• Declare a cursor variable with parameters

• Open the cursor using the OPEN statement and pass in the parameter values

• Fetch rows from the cursor using the FETCH statement

• Close the cursor using the CLOSE statement

Rownum is a pseudocolumn in Oracle that assigns a unique number to each row returned by a query.

• Rownum starts with 1 and increments by 1 for each row returned by the query.

• The expression Rownum > 4 is correct and will return all rows with a Rownum greater than 4.

• Rownum can be used to limit the number of rows returned by a query, for example, 'SELECT * FROM table WHERE Rownum <= 10'.

Procedure is a set of instructions that performs a specific task, while function returns a value after performing a specific task.

• Procedure does not return a value, while function returns a value

• Procedure can modify the values of input parameters, while function cannot

• Functions can be called from within a procedure, but procedures cannot be called from within a function

An offline store management system is a software that helps manage inventory, sales, and customer data in a physical store without an internet connection.

• The system should have a database to store product information, sales data, and customer information.

• It should have a user-friendly interface for employees to input and access data.

• The system should be able to generate reports on sales, inventory levels, and customer data.

• It should have a backup system in case of data loss o...read more

User defined exceptions can be defined by creating a new class that extends the Exception class.

• Create a new class that extends the Exception class

• Add constructors to the class to initialize the exception

• Throw the exception using the 'throw' keyword

Yes, I have experience with CI/CD, Microservices, Junits, Async APIs, and Multithreading.

• Implemented CI/CD pipelines using Jenkins for automated testing and deployment

• Developed microservices architecture using Spring Boot and Docker containers

• Wrote Junit tests for unit testing and integration testing

• Worked on building async APIs using frameworks like Node.js and Spring WebFlux

• Utilized multithreading in Java applications for improved performance

Fetch leaderboard ranking for a given user and neighbors, handle huge dataset

• Use a distributed system like Hadoop or Spark to handle the huge dataset

• Implement a ranking algorithm to efficiently fetch the leaderboard

• Retrieve the ranking for the given user and fetch 5 users above and below

• Ensure the solution is scalable and can handle increasing data size

Design a CRUD of saving and getting a message in Spring boot

• Create a Message entity with fields like id, content, createdDate

• Create a MessageRepository interface extending JpaRepository

• Create a MessageService class with methods for saving, getting, updating, and deleting messages

• Create a MessageController class with endpoints for CRUD operations using @RestController and @RequestMapping annotations

Design a high level design for a subset of Instagram features.

• User authentication and profile creation

• Photo and video uploading with filters

• News feed displaying posts from followed users

• Like, comment, and share functionality

• Direct messaging between users

Find maximum sum of distinct subarray with length k using sliding window technique.

• Use a sliding window of size k to iterate through the array

• Keep track of the sum of elements within the window

• Maintain a set to keep track of distinct elements in the window

• Slide the window by removing the leftmost element and adding the rightmost element

• Update the maximum sum as you iterate through the array

Design a communication system for chat/notifications

• Use a real-time messaging protocol like WebSocket for chat functionality

• Implement push notifications for notifications to keep users updated

• Include features like read receipts, typing indicators, and message history

• Consider implementing message encryption for security

• Allow users to customize notification settings for different types of messages

Design a system for generating report cards with dynamic class/subjects

• Create a database to store student information, class details, and subject details

• Allow users to input class details and subjects for each class dynamically

• Design a template for report cards that can be customized based on class and subjects

• Implement a feature to generate report cards based on the selected class and subjects

• Include options for teachers to input grades and comments for each subject

Implemented a real-time collaborative editing feature using WebSockets

• Designed a scalable architecture to handle concurrent edits from multiple users

• Implemented conflict resolution algorithms to ensure data consistency

• Utilized WebSockets for bi-directional communication between clients and server

CNN stands for Convolutional Neural Networks, used for image recognition. YOLO (You Only Look Once) is a real-time object detection model.

• CNNs are deep learning models specifically designed for processing visual data like images and videos.

• They consist of multiple layers such as convolutional, pooling, and fully connected layers to extract features from the input data.

• YOLO is a popular object detection model that divides the image into a grid and predicts bounding boxes and c...read more

Book My Show is a high-level system for booking movie tickets and event tickets online.

• Users can search for movies or events, view showtimes, and book tickets online.

• The system should handle user authentication, payment processing, and ticket confirmation.

• It should also include features like seat selection, seat availability updates, and booking history.

• The system should have a database to store movie/event information, user data, and transaction details.

The level of a node in a binary tree is determined by the number of edges on the path from the root to that node.

• The level of the root node is 0.

• To find the level of a node, traverse the tree starting from the root and increment a level counter as you move down the tree.

• The level of a node can also be determined by its distance from the root node.

Design a book reader service similar to Kindle

• Implement a user-friendly interface for browsing and purchasing books

• Include features like bookmarking, highlighting, and note-taking

• Support various file formats such as PDF, EPUB, and MOBI

• Provide options for customization like font size, background color, and reading progress tracking

Design a framework for exception handling in a LRU Cache system

• Implement try-catch blocks to handle exceptions

• Use specific exception classes for different types of errors

• Consider using logging mechanisms to track and debug exceptions

• Implement a global exception handler to catch unhandled exceptions

Search for a target value in a sorted rotated array.

• Use binary search to find the pivot point where the array is rotated.

• Determine which half of the array the target value may lie in based on the pivot point.

• Continue binary search in the appropriate half of the array to find the target value.

Throttling limits the number of times a function can be called over a certain period, while debouncing delays the execution of a function until a certain amount of time has passed without it being called.

• Throttling ensures that a function is not called more than once in a specified time frame.

• Debouncing delays the execution of a function until a certain amount of time has passed without it being called.

• Throttling is often used in scenarios like scroll events to limit the rate...read more

ViewModel is a class that is responsible for preparing and managing the data for an activity or fragment.

• ViewModels are designed to store and manage UI-related data in a lifecycle-conscious way.

• They survive configuration changes, such as screen rotations, and are not destroyed when the activity or fragment is destroyed and recreated.

• ViewModels are typically used to hold data that is needed by multiple fragments or activities within an application.

• They can also be used to comm...read more

Android is a mobile operating system developed by Google, based on the Linux kernel and designed primarily for touchscreen devices.

• Android is open-source and allows developers to create applications using Java or Kotlin.

• It has a large user base and a wide range of devices running on different versions of the OS.

• Android provides a rich set of APIs for accessing device hardware, sensors, and services.

• Google Play Store is the official app store for Android, where users can downl...read more

Residual networks are a type of neural network architecture that utilize skip connections to help with training deep networks.

• Residual networks were introduced by Kaiming He et al. in the paper 'Deep Residual Learning for Image Recognition'.

• They address the problem of vanishing gradients in deep networks by introducing skip connections that allow the gradient to flow more easily.

• Residual networks have been widely used in computer vision tasks, such as image classification and...read more

Merge two sorted arrays and find the median

• Merge the two arrays into one sorted array

• Calculate the median based on the length of the merged array

• Handle cases where the total length is even or odd

Code working and its functionalities

• Code working refers to the process of writing, compiling, and executing code to achieve a desired outcome

• Functionalities of code include data manipulation, logic implementation, and interaction with external systems

• Examples of code working functionalities include sorting algorithms, database queries, and user interface design

I manage states by using state management libraries like Redux and MobX, and by following best practices like separating UI and business logic.

• Use state management libraries like Redux or MobX to centralize and manage application state

• Follow best practices like separating UI and business logic to keep states manageable and maintainable

• Utilize local component state for simple and isolated state management within components

States in Flutter are the data values that can change during the lifetime of a widget.

• States are used to manage the data that changes over time in a Flutter application.

• There are two types of states in Flutter: Stateful and Stateless.

• Stateful widgets have mutable state that can change over time, while stateless widgets are immutable.

• Examples of states in Flutter include user input, network requests, and animations.

LLD stands for Low Level Design, which includes designing API and database schema for a software system.

• LLD involves detailed design of individual components/modules of a software system.

• API design includes defining endpoints, request/response formats, authentication mechanisms, etc.

• DB schema design involves defining tables, relationships, indexes, constraints, etc.

• LLD ensures that the system is scalable, maintainable, and efficient.

• Example: For an e-commerce platform, LLD wo...read more

A balanced tree is a tree where the heights of the two subtrees of every node never differ by more than 1.

• Traverse the tree and calculate the height of each subtree

• Check if the heights of the left and right subtrees differ by more than 1

• Repeat the process for all nodes in the tree

Coroutines are a type of computer program component that allow for cooperative multitasking and non-preemptive scheduling.

• Coroutines are similar to subroutines, but they can pause and resume execution at specific points.

• They are useful for tasks that involve asynchronous operations or managing concurrent tasks.

• Coroutines can be implemented using language-specific constructs or libraries, such as async/await in Python or Kotlin's coroutines.

• Example use cases include network pr...read more

A sealed class is a class that cannot be inherited or extended by other classes.

• Sealed classes are used to restrict inheritance and ensure that a class cannot have subclasses.

• They are often used when a class is considered complete and should not be extended further.

• Sealed classes can have abstract members and can be used as base classes for other classes.

• An example of a sealed class in C# is the System.String class.

Designing a posts feed in React.js

• Use state management library like Redux to store and manage posts data

• Create a Post component to display each post with relevant information

• Implement infinite scrolling or pagination for loading more posts

• Include features like like, comment, and share buttons for each post

Throttling is a process of limiting the number of requests or data flow in order to prevent overload.

• Throttling is used to control the rate of data transfer or API requests to prevent server overload.

• It can be implemented by setting limits on the number of requests per second or minute.

• Throttling can help maintain system stability and prevent performance degradation.

• Examples include rate limiting on API endpoints to prevent abuse or setting limits on data transfer speeds.

System design for hotel management including booking, check-in/out, room allocation, and payment processing.

• Use a database to store information about rooms, bookings, guests, and payments.

• Implement a booking system that allows guests to search for available rooms based on dates and preferences.

• Include a check-in/out process that updates room availability and guest information.

• Design a room allocation algorithm to optimize room usage and guest satisfaction.

• Integrate a payment ...read more

Find the second highest number in an array.

• Sort the array in descending order

• Return the element at index 1

Design a movie booking system

• Create a database to store movie details, showtimes, and seat availability

• Develop a user interface for customers to browse movies, select showtimes, and book seats

• Implement a payment gateway for secure transactions

• Include features like seat selection, seat reservation timeout, and booking confirmation

Design a Google calendar

• Allow users to create events and set reminders

• Provide options for recurring events

• Include sharing and collaboration features

• Integrate with other Google services like Gmail and Maps

Find if there are three elements in an array that sum up to a given target value.

• Sort the array first to make the solution more efficient.

• Use two pointers technique to find the triplet sum.

• Handle duplicates by skipping them while iterating.

Design LLD of Dream11

• Use microservices architecture for scalability and flexibility

• Implement user authentication and authorization for secure access

• Utilize caching mechanisms to improve performance

• Design database schema for storing user data, teams, matches, and scores

• Include features like creating teams, joining contests, and viewing live scores

Initialisers in Swift are special methods used to create and initialise instances of a class, struct, or enum.

• Initialisers are used to set up the initial state of an instance.

• They are defined using the 'init' keyword.

• There are designated initialisers and convenience initialisers.

• Designated initialisers are the primary initialisers for a class.

• Convenience initialisers are secondary initialisers that call a designated initialiser.

• Example: init(name: String) { self.name = name }

Polyfill for debounce function in JavaScript

• Implement a debounce function that delays invoking a function until after a certain amount of time has passed without it being called again

• Use setTimeout to delay the execution of the function

• Clear the timeout if the function is called again within the specified time frame

• Return a function that can be called to trigger the debounced function

Search for a target value in a 2D matrix and return true if found, false otherwise.

• Start from the top right corner or bottom left corner for efficient search

• Use binary search in each row or column to narrow down the search space

• Handle edge cases like empty matrix or target not found

To find the mirror of a tree, we need to swap the left and right children of each node recursively.

• Start from the root node of the tree

• Swap the left and right children of the current node

• Recursively call the mirror function on the left and right subtrees

Designing posts for social media platforms

• Consider the target audience and platform

• Use eye-catching visuals and engaging captions

• Include relevant hashtags and tags

• Maintain consistency in branding and tone

• Monitor engagement and adjust strategy accordingly

Design a parking lot

• Consider the size and capacity of the parking lot

• Decide on the layout and organization of parking spaces

• Implement a system to manage parking availability and reservations

• Include features like ticketing, payment, and security

• Consider accessibility and convenience for drivers