100+ Software Development Engineer II Interview Questions and Answers

Different states in Activity lifecycle include onCreate, onStart, onResume, onPause, onStop, onDestroy.

• onCreate - Activity is being created

• onStart - Activity is becoming visible to the user

• onResume - Activity is in the foreground and has focus

• onPause - Activity is partially visible but still running

• onStop - Activity is no longer visible to the user

• onDestroy - Activity is being destroyed

CDC stands for Change Data Capture in SQL Server.

• CDC is a feature in SQL Server that captures changes made to data in a table.

• It allows you to track insert, update, and delete operations on the table.

• CDC uses a separate table to store the changes made to the tracked table.

• It is useful for auditing, data replication, and data warehousing purposes.

Design a search service for E-commerce website.

• Utilize a search engine like Elasticsearch for fast and accurate search results

• Implement filters for refining search results by category, price range, brand, etc.

• Include autocomplete suggestions to assist users in their search queries

• Optimize search results based on user behavior and preferences

• Allow users to save their search queries and receive notifications for new matching products

Use a combination of hash table and linked list to achieve O(1) operations for a Hash Map.

• Use a hash table to store key-value pairs and a linked list to handle collisions.

• Implement a hash function to map keys to indices in the hash table.

• For each key, calculate the hash value and store the corresponding value in the hash table at that index.

• To handle collisions, use separate chaining with linked lists at each index of the hash table.

• When searching for a key, calculate the has...read more

Security practices in frontend and backend development are crucial for protecting user data and preventing cyber attacks.

• Implement input validation to prevent SQL injection and cross-site scripting attacks

• Use HTTPS protocol to encrypt data transmission between frontend and backend

• Implement authentication and authorization mechanisms to control access to sensitive data

• Regularly update software libraries and frameworks to patch security vulnerabilities

• Implement security headers...read more

Find the longest sub string with non repeating chars

• Use a sliding window approach to track the current substring

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

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

Find the maximum profit that can be made by buying and selling stocks in an array.

• Use a greedy approach to find the maximum profit by keeping track of the minimum price and updating the maximum profit.

• Iterate through the array and calculate the difference between each element and the minimum price seen so far.

• Return the maximum profit obtained from the array.

High-level design for a Dropbox-like system

• Use a distributed file system to store files

• Implement a synchronization mechanism to ensure consistency across devices

• Use encryption to protect user data

• Implement a user authentication and authorization system

• Provide a web interface and mobile apps for easy access

• Consider scalability and fault tolerance

• Implement version control to allow users to revert to previous versions of files

Design a system to manage people

• Identify the roles and responsibilities of people in the organization

• Create a database to store employee information

• Develop a user interface for employees to update their information

• Implement a system for managers to approve employee requests

• Integrate with payroll and benefits systems

• Ensure data security and privacy

Rails use controllers to handle incoming API requests, routing them to the appropriate actions in the application.

• Rails routes incoming API requests to the appropriate controller action based on the URL and HTTP method.

• Controllers in Rails contain the logic to process the request, interact with the model layer, and render a response.

• Rails uses RESTful conventions to map HTTP methods (GET, POST, PUT, DELETE) to controller actions (index, create, update, destroy).

• Example: When ...read more

SOLID principle is a set of five design principles to make software designs more understandable, flexible, and maintainable.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable with objects of its subclasses without affecting the program's correctness.

• I - Interface S...read more

Implement an in-memory backend for a social media app

• Use a data structure like a hashmap to store user profiles, posts, and relationships

• Implement functions for creating, updating, and deleting user profiles and posts

• Handle relationships between users such as following and friend requests

Use asyncio library to run async tasks in Python

• Import asyncio library

• Define async functions using 'async def'

• Use 'await' keyword to run async functions

• Use asyncio.run() to run the async tasks

Count number of islands and solve the House Robber problem.

• Count number of islands: Use DFS or BFS to traverse the grid and mark visited cells as part of an island.

• House Robber: Use dynamic programming to calculate the maximum amount of money that can be robbed without alerting the police.

• Example for counting number of islands: Given grid = [['1','1','0','0','0'],['1','1','0','0','0'],['0','0','1','0','0'],['0','0','0','1','1']], the number of islands is 3.

• Example for House R...read more

Singleton is a design pattern that restricts the instantiation of a class to one object.

• Singleton pattern ensures that a class has only one instance and provides a global point of access to it.

• Commonly used in scenarios where only a single instance of a class is needed, such as database connections or logging.

• Implementation involves a private constructor, a static method to access the instance, and a static variable to hold the instance.

• Example: public class Singleton { priva...read more

Garbage collection in C# automatically manages memory by reclaiming unused objects.

• Garbage collection in C# uses a mark-and-sweep algorithm to identify and reclaim memory that is no longer in use.

• It runs in the background and periodically checks for objects that are no longer reachable.

• Garbage collection helps prevent memory leaks and makes memory management easier for developers.

• Example: C# automatically deallocates memory for objects like strings, arrays, and other data typ...read more

Swiggy Delivery Assignment System HLD

• Use a centralized system to assign delivery tasks to delivery executives based on various factors like distance, availability, and ratings

• Implement a matching algorithm to efficiently assign tasks to the nearest available executive

• Utilize real-time tracking to monitor the status of each delivery and optimize routes for faster delivery times

LLD for Swiggy Delivery Assignment System

• Use a centralized system to assign delivery tasks to delivery executives based on various factors like distance, availability, ratings, etc.

• Implement a matching algorithm to efficiently assign tasks to the most suitable delivery executive.

• Include features like real-time tracking, notifications, and reassignment in case of unavailability or delays.

• Consider scalability and performance optimizations to handle a large number of concurrent ...read more

Design a Unix Find File Library

• Implement functions to search for files based on criteria like name, size, permissions, etc.

• Utilize system calls like opendir(), readdir(), and stat() to traverse directories and gather file information.

• Support options for recursive searching, filtering by file type, and specifying search depth.

• Include error handling for cases like permission denied or invalid paths.

• Provide a user-friendly interface with options for displaying results in differe...read more

Reading CSV without pandas involves using built-in Python modules like csv.

• Use the csv module to open and read the CSV file

• Iterate through the rows and process the data accordingly

• Handle any necessary data conversions or manipulations manually

List and tuple are data structures in Python used to store multiple items. Lists are mutable, while tuples are immutable.

• List is denoted by square brackets [] and can be modified after creation

• Tuple is denoted by parentheses () and cannot be modified after creation

• Lists are used when the order of elements needs to be preserved and elements can be changed

• Tuples are used when the order of elements needs to be preserved but elements should not be changed

• Example of list: my_list ...read more

Find the indices of the subarray with the maximum product in an array.

• Iterate through the array and keep track of the maximum product, starting index, and ending index.

• Consider both positive and negative numbers while calculating the product.

• Return the starting and ending indices of the subarray with the maximum product.

Design a bike rental shop system.

• Create a database to store information about bikes, customers, rentals, etc.

• Develop a user-friendly website or mobile app for customers to browse and rent bikes.

• Implement a payment system for customers to pay for rentals.

• Have a system in place for bike maintenance and tracking.

• Consider implementing a rating system for customers to provide feedback on bikes and service.

Design a least recently used cache system.

• Use a combination of a hash map and a doubly linked list to keep track of the least recently used items.

• When a new item is accessed, move it to the front of the list.

• If the cache is full, remove the least recently used item from the end of the list.

The current product follows a microservices architecture.

• The product is divided into multiple independent services.

• Each service has its own database and communicates with other services through APIs.

• The architecture allows for scalability and flexibility.

• Examples of services include user management, payment processing, and inventory management.

Design a database schema for a train booking system

• Create tables for trains, stations, bookings, users, and tickets

• Use foreign keys to establish relationships between tables

• Include columns for train schedule, seat availability, and user information

• Consider implementing indexes for faster query performance

A linked list is a data structure where each element points to the next element in the sequence.

• Create a Node class with data and next pointer

• Initialize head pointer to null for an empty list

• Implement methods like insert, delete, search, and display

• Example: Node class - class Node { int data; Node next; }

Merge two sorted arrays using Merge Sort algorithm.

• Create a new array to store the merged result

• Compare elements from both arrays and add the smaller one to the new array

• Continue this process until all elements are merged

Viewmodel is a design pattern that separates the data of an application from the UI logic.

• Viewmodel stores and manages UI-related data in a lifecycle-conscious way.

• It survives configuration changes and is not destroyed when the UI is destroyed.

• Viewmodel is typically used in conjunction with LiveData to update the UI when the data changes.

• It helps in keeping the UI logic separate from the UI components, making the code more maintainable and testable.

Design a system to manage deliveries efficiently

• Use a centralized database to store information about deliveries, drivers, and customers

• Implement a tracking system to monitor the status of deliveries in real-time

• Include features like route optimization, delivery scheduling, and notifications for customers

• Consider scalability and reliability to handle a large volume of deliveries

• Integrate with mapping APIs for accurate location tracking

T-SQL concepts include data manipulation, querying, transactions, and stored procedures.

• Data manipulation involves inserting, updating, and deleting data in a database.

• Querying involves retrieving data from a database using SELECT statements.

• Transactions ensure that a group of database operations are completed as a single unit of work.

• Stored procedures are precompiled SQL statements that can be executed multiple times.

• Other concepts include views, triggers, and user-defined f...read more

Reverse a linked list by group of given size

• Divide the linked list into groups of given size

• Reverse each group individually

• Connect the reversed groups to form the final linked list

Sort array of strings to the left and right

• Use a custom comparator function to sort the array based on specific criteria

• Split the array into two parts based on the sorted order

• Join the two parts back together to get the final sorted array

Check if a linked list is a palindrome

• Traverse the linked list to find the middle point

• Reverse the second half of the linked list

• Compare the first half with the reversed second half

Design a multiplayer game similar to PUBG.

• Create a large map with various terrains and buildings

• Allow players to form teams and communicate with each other

• Include a variety of weapons and equipment for players to find and use

• Implement a shrinking play area to force players into closer combat

• Include a ranking system to encourage competition and skill improvement

Error handling in SQL involves using try-catch blocks, raising custom errors, and using error functions.

• Use TRY-CATCH blocks to handle errors gracefully

• Raise custom errors using RAISEERROR function

• Use error functions like ERROR_MESSAGE(), ERROR_NUMBER(), ERROR_SEVERITY(), ERROR_STATE(), and ERROR_LINE() to retrieve error information

Design a like and comments system for a social media platform

• Use a relational database to store user likes and comments

• Implement a feature to allow users to like posts and comments

• Include a feature to display the number of likes and comments on each post

• Allow users to comment on posts and reply to comments

• Implement a notification system for users to be notified of new likes and comments on their posts

Find the maximum sum by picking corner elements of a matrix

• Start by selecting the four corner elements of the matrix

• Compare the sum of the diagonally opposite corners and choose the pair with the higher sum

• Repeat the process with the remaining elements until all corners are picked

SQL query to fetch specific information from a database

• Use SELECT statement to specify the columns you want to retrieve

• Use FROM clause to specify the table from which to retrieve the data

• Use WHERE clause to add conditions for filtering the data

• Use JOIN clause to combine data from multiple tables if needed

Bulk insert is a process of inserting a large amount of data into a database at once.

• Efficient way to insert large volumes of data into a database

• Reduces overhead by minimizing the number of transactions

• Often used for data migration or loading data from external sources

Synonyms are words that have similar meanings.

• Synonyms are words that can be used interchangeably in a sentence.

• They help in avoiding repetition and adding variety to the language.

• Examples include: big and large, happy and joyful, fast and quick.

Use regular expressions to extract data from a multi-line string

• Use the re module in Python to create a regular expression pattern

• Use the re.findall() function to extract data based on the pattern

• Consider using groups in the regular expression pattern to capture specific data

High level design for 3 products

• Identify user needs and requirements

• Create a conceptual design for each product

• Define the architecture and components

• Consider scalability, security, and performance

• Document the design and review with stakeholders

Design a parking lot system including classes, functions, and data structures.

• Create a ParkingLot class with attributes like capacity, available spots, and a list of parking spots.

• Implement a Vehicle class with attributes like license plate number, size, and type.

• Design a ParkingSpot class with attributes like spot number, availability, and size.

• Use data structures like arrays or lists to manage parking spots and vehicles efficiently.

• Implement methods like parkVehicle(), remo...read more

Reverse each word in a given array of strings

• Iterate through each string in the array

• Split each string into individual words

• Reverse each word and join them back together

• Return the modified array of strings

Design a recommendation engine for personalized suggestions based on user preferences and behavior.

• Collect user data such as browsing history, purchase history, ratings, and interactions.

• Use collaborative filtering, content-based filtering, or hybrid approaches to generate recommendations.

• Implement algorithms like matrix factorization, k-nearest neighbors, or neural networks for personalized suggestions.

• Regularly update recommendations based on user feedback and behavior.

• Prov...read more

Binary search algorithm can be used to find a target element in a sorted array.

• Implement binary search algorithm to efficiently find the target element in a sorted array.

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

• Continue dividing the search range in half until the target element is found or the search range is empty.