100+ Gabriel India Interview Questions and Answers

Optimize job scheduling code

• Use priority queue to efficiently schedule jobs

• Implement dynamic programming to optimize job sequence

• Consider parallel processing to reduce overall time

• Use efficient data structures to store job information

Code to find max length subarray matching the given sum

• Use a sliding window approach to iterate through the array

• Keep track of the current sum and the maximum length subarray

• If the current sum exceeds the given sum, move the window's left pointer

• If the current sum matches the given sum, update the maximum length subarray

• Return the maximum length subarray

Use Sieve of Eratosthenes algorithm to optimize prime number generation.

• Implement Sieve of Eratosthenes algorithm to eliminate non-prime numbers

• Use boolean array to mark non-prime numbers

• Start with 2 and mark all its multiples as non-prime, then move to next unmarked number

• Stop at square root of the upper limit to optimize performance

SQL query to retrieve output from given tables

• Identify the tables and their relationships

• Determine the columns to be selected

• Use appropriate join and filter conditions

• Group and aggregate data if required

CRFS stands for Continuous Randomized Feedback System. It is a method used in clinical trials to collect data from patients.

• CRFS is a way to collect data from patients in clinical trials in real-time.

• It involves randomizing questions and collecting feedback from patients at various intervals.

• The data collected through CRFS can help researchers make informed decisions about the efficacy of a treatment.

• CRFS can be implemented through various methods such as mobile apps, web-bas...read more

An e2e system architecture design for user input to response output

• Identify user requirements and define system goals

• Choose appropriate technologies and frameworks

• Design system components and their interactions

• Ensure scalability, reliability, and security

• Test and validate the system before deployment

Store newspapers of a company

• Create a database to store newspaper information

• Use a unique identifier for each newspaper

• Include fields for date, title, author, and content

• Implement a search function for easy retrieval

• Consider implementing a backup system for data security

AWS services include EC2 for virtual servers. To create and launch EC2 instances, use the AWS Management Console, CLI, or SDK.

• Access the AWS Management Console and navigate to the EC2 dashboard

• Click on 'Launch Instance' to choose an Amazon Machine Image (AMI), instance type, and configure instance details

• Review and launch the instance, selecting key pair for SSH access

• Use AWS CLI or SDK to create and launch EC2 instances programmatically

Designing APIs and finding second largest value in SQL query.

• For API design, consider RESTful principles and use clear and concise naming conventions.

• For finding second largest value in SQL, use ORDER BY and LIMIT clauses.

• Consider edge cases such as duplicates and null values.

• Test thoroughly to ensure correct functionality.

Python is a general-purpose language while Node.JS is a JavaScript runtime environment.

• Python is used for web development, data analysis, artificial intelligence, and scientific computing.

• Node.JS is used for building scalable network applications and real-time web applications.

• Python is slower than Node.JS in terms of performance.

• Python has a larger standard library than Node.JS.

• Python is easier to learn and has a simpler syntax than Node.JS.

SQL is a relational database management system while NoSQL is a non-relational database management system.

• SQL databases are table-based while NoSQL databases are document-based, key-value pairs, graph databases, or column-based.

• SQL databases are structured while NoSQL databases are unstructured.

• SQL databases use SQL (Structured Query Language) for querying and managing data while NoSQL databases use different query languages like MongoDB uses JSON-like documents.

• SQL databases...read more

Implement a min stack using a single stack

• Create a stack to hold the elements and another stack to hold the minimum values

• When pushing an element, check if it's smaller than the current minimum and push it to the minimum stack if it is

• When popping an element, check if it's the current minimum and pop it from the minimum stack if it is

• To get the minimum value, return the top element of the minimum stack

Monolith is a single, large application while microservices are smaller, independent services. Microservices are better for scalability and flexibility.

• Monolith is a single, large application where all components are tightly coupled. Microservices are smaller, independent services that communicate with each other through APIs.

• Monoliths are easier to develop and deploy initially but become harder to maintain and scale as they grow. Microservices allow for better scalability an...read more

Answering questions on projects, database schema design of Codechef, SQL queries, and CN.

• Projects involved developing a web application for managing employee data and a mobile app for tracking expenses.

• Database schema design of Codechef involved creating tables for users, problems, submissions, and contests.

• SQL queries related to Codechef included retrieving user details, problem submissions, and contest rankings.

• Questions on CN covered topics such as network protocols, OSI m...read more

Q1 - Pre order traversal without recursion. Q2 - Reverse a linked list.

• Q1: Use a stack to keep track of nodes. Start with root, push it to stack. Pop top node, print it, push right and left children to stack.

• Q2: Traverse the linked list and change the direction of the pointers. Set the head of the reversed list as the last node of the original list.

CLI snake and ladders game code

• Create a board with 100 cells using a 10x10 array

• Define snakes and ladders positions as an array of tuples

• Use a loop to alternate player turns and move them based on dice roll

• Check for snakes and ladders and update player position accordingly

• Print the board after each turn and declare winner when a player reaches cell 100

Sort a string based on the frequency of its characters.

• Create a hash table to store the frequency of each character.

• Sort the characters based on their frequency using a sorting algorithm.

• Reconstruct the string based on the sorted characters and their frequency.

Semaphore is used to control access to a resource with limited capacity while mutex is used to synchronize access to a shared resource.

• Semaphore allows multiple threads to access a resource simultaneously up to a certain limit while mutex allows only one thread to access a shared resource at a time.

• Semaphore can be used to solve the producer-consumer problem while mutex can be used to solve the critical section problem.

• Semaphore can be binary or counting while mutex is always...read more

Threads are lightweight processes that enable multitasking within a single process.

• Threads allow multiple tasks to be executed concurrently within a single process.

• They share the same memory space and resources of the parent process.

• Threads can improve performance by utilizing available CPU resources more efficiently.

• Examples include web servers handling multiple requests simultaneously and video games rendering graphics while processing user input.

CORS stands for Cross-Origin Resource Sharing. It is a security feature implemented in web browsers to restrict web pages from making requests to a different domain.

• CORS is used to prevent malicious websites from accessing sensitive data from other websites.

• To handle CORS, the server needs to include specific headers in the response to allow the browser to make requests from a different domain.

• The most common header used to handle CORS is 'Access-Control-Allow-Origin'. It spe...read more

Sort an array of 0s, 1s, 2s in linear time.

• Use three pointers to keep track of the positions of 0s, 1s, and 2s.

• Traverse the array once and swap elements based on their values.

• The final array will have 0s, 1s, and 2s grouped together in that order.

I am excited to join Hashedin because of its reputation for innovative solutions and collaborative work culture.

• Hashedin has a strong track record of delivering cutting-edge technology solutions for clients across various industries.

• I am impressed by the company's focus on collaboration and teamwork, which aligns with my own work style.

• I am excited about the opportunity to work with a talented and diverse team of professionals at Hashedin.

• Hashedin's commitment to employee gro...read more

Check if there exists a pair of numbers in the array that add up to a given sum.

• Iterate through the array and for each element, check if the difference between the sum and the element exists in the array using a hash table.

• Alternatively, sort the array and use two pointers to traverse from both ends towards the middle, adjusting the pointers based on the sum of the current pair.

Sharding is a database partitioning technique to improve performance and scalability.

• It involves dividing a large database into smaller, more manageable parts called shards.

• Each shard contains a subset of the data and can be stored on a separate server.

• Sharding can be implemented using different strategies such as range-based, hash-based, or round-robin.

• It requires careful planning and coordination to ensure data consistency and availability.

• Examples of sharding in popular da...read more

A Reddit-like application for sharing and discussing content

• User authentication and authorization

• Post creation and voting system

• Commenting system

• Subreddit creation and management

• Search functionality

• Real-time updates using websockets

Node.js is a powerful and efficient server-side JavaScript runtime environment.

• Node.js is fast and scalable, making it ideal for building real-time applications.

• It uses an event-driven, non-blocking I/O model, which makes it lightweight and efficient.

• Node.js has a large and active community, with many useful libraries and modules available.

• It allows for easy sharing of code between the server and client, using JavaScript on both sides.

• Node.js is cross-platform, meaning it can...read more

Method overloading is having multiple methods with the same name but different parameters. Method overriding is having a subclass method with the same name and parameters as a superclass method.

• Method overloading is used to provide different ways of calling the same method with different parameters.

• Method overriding is used to provide a specific implementation of a method in a subclass that is already defined in a superclass.

• Method overloading is resolved at compile-time base...read more

Hashedin is a leading software development company with a focus on delivering innovative solutions.

• Expertise in cutting-edge technologies

• Proven track record of successful project delivery

• Strong emphasis on client satisfaction

• Collaborative and agile approach to development

• Dedicated team of experienced professionals

OS processes are instances of a program that are being executed by the operating system.

• Processes are managed by the operating system's scheduler.

• Each process has its own memory space and system resources.

• Processes can communicate with each other through inter-process communication (IPC).

• Examples of processes include web browsers, media players, and text editors.

Finding the Kth smallest element in an array.

• Sort the array and return the Kth element.

• Use a min heap to find the Kth smallest element.

• Use quickselect algorithm to find the Kth smallest element.

• Divide and conquer approach using binary search.

• Use selection algorithm to find the Kth smallest element.

Rotate an array of strings k times

• Create a temporary array to store elements that will be rotated

• Use modulo operator to handle cases where k is greater than array length

• Update the original array with elements from the temporary array

Abstraction is the concept of hiding complex implementation details and showing only the necessary information. Encapsulation is bundling data and methods that operate on the data into a single unit.

• Abstraction focuses on what an object does rather than how it does it

• Encapsulation restricts access to some of an object's components, protecting the object's integrity

• Abstraction allows for creating simple interfaces for complex systems

• Encapsulation helps in achieving data hiding...read more

I chose HashedIn for its innovative projects and collaborative work culture.

• Innovative projects attracted me to HashedIn

• I value the collaborative work culture at HashedIn

• I appreciate the opportunities for growth and learning at HashedIn

• I was impressed by the team's technical expertise during the interview process

Deadlock is a situation where two or more processes are unable to proceed because they are waiting for each other to release resources.

• Occurs in multi-process systems

• Processes hold resources and wait for others to release resources

• Can lead to system freeze or crash

• Prevented by proper resource allocation and scheduling

• Example: Two trains on a single track, each waiting for the other to pass first

Use a hash table to find two numbers in a linked list that add up to a target sum.

• Traverse the linked list and store each node's value in a hash table along with its index.

• For each node, check if the difference between the target sum and the current node's value exists in the hash table.

• If it does, return the indices of the two nodes.

• Example: Given linked list 2 -> 4 -> 3 -> 5 and target sum 7, return indices 1 and 2.

The maximum subarray sum problem involves finding the contiguous subarray within a one-dimensional array of numbers which has the largest sum.

• Use Kadane's algorithm to find the maximum subarray sum efficiently.

• Consider all possible subarrays and calculate their sums to find the maximum.

• Dynamic programming can be used to solve this problem efficiently.

• Example: For array [-2, 1, -3, 4, -1, 2, 1, -5, 4], the maximum subarray sum is 6 (from index 3 to 6).

Low level design for authentication

• Define authentication requirements

• Choose appropriate authentication mechanism

• Design authentication flow

• Implement secure storage of credentials

• Consider multi-factor authentication

• Include error handling and logging

Database design for Instagram platform

• Create tables for users, posts, comments, likes, followers, and hashtags

• Use primary and foreign keys to establish relationships between tables

• Include fields such as user_id, post_id, comment_id, like_id, follower_id, and hashtag_id

• Implement indexes for faster data retrieval

• Consider scalability and performance optimization techniques

Multiple inheritance is a feature in object-oriented programming where a class can inherit attributes and methods from more than one parent class.

• Allows a class to inherit attributes and methods from multiple parent classes

• Can lead to the Diamond Problem where ambiguity arises if two parent classes have a method with the same name

• Languages like C++ support multiple inheritance

Count occurrence of element in an array of strings

• Use a loop to iterate through the array

• Use a dictionary to store the count of each element

• Increment the count for each element encountered

System design for the game of Snake and Ladder

• Create a board with 100 cells and mark the positions of snakes and ladders

• Implement a player class with a current position on the board

• Roll a dice to move the player and check for snakes and ladders

• Keep track of player scores and winner at the end of the game

I handle pressure by prioritizing tasks, staying organized, seeking support when needed, and practicing stress-relief techniques.

• Prioritize tasks based on deadlines and importance

• Stay organized with to-do lists and calendars

• Seek support from colleagues or supervisors when feeling overwhelmed

• Practice stress-relief techniques such as deep breathing or exercise

• Maintain a positive attitude and focus on problem-solving

Asymptotic notation is a way to describe the performance of an algorithm in terms of its input size.

• Asymptotic notation is used to analyze the efficiency of algorithms by focusing on how they behave as the input size approaches infinity.

• Common notations include O (Big O), Ω (Big Omega), and Θ (Big Theta), which represent the worst-case, best-case, and average-case time complexity respectively.

• For example, if an algorithm has a time complexity of O(n^2), it means that the algo...read more

Spark Memory management involves configuring memory allocation, monitoring memory usage, and optimizing performance.

• Set memory allocation parameters in Spark configuration (e.g. spark.executor.memory, spark.driver.memory)

• Monitor memory usage using Spark UI or monitoring tools like Ganglia

• Optimize performance by tuning memory allocation based on workload and cluster resources

• Use techniques like caching and persistence to reduce memory usage and improve performance

Transpose a matrix by swapping rows with columns

• Iterate through each row and column and swap the elements

• Create a new matrix with swapped rows and columns

• Ensure the new matrix has the correct dimensions

Implement a swap method for two variables.

• Create a temporary variable to store the value of one variable.

• Assign the value of the second variable to the first variable.

• Assign the value of the temporary variable to the second variable.

The depth of a binary tree is the number of edges on the longest path from the root node to a leaf node.

• Depth of a binary tree can be calculated recursively by finding the maximum depth of the left and right subtrees and adding 1.

• The depth of a binary tree with only one node (the root) is 0.

• Example: For a binary tree with root node A, left child B, and right child C, the depth would be 1.