200+ Member Technical Staff Interview Questions and Answers

Vtable and VPTR are used in C++ for implementing polymorphism through virtual functions.

• Vtable (Virtual Table) is a table of function pointers used to implement dynamic dispatch in C++ for virtual functions.

• VPTR (Virtual Pointer) is a pointer that points to the Vtable of an object, allowing dynamic binding of virtual functions at runtime.

• Vtable is created for each class that has virtual functions, containing pointers to the virtual functions of that class.

• VPTR is a hidden mem...read more

Designing a thread-safe concurrent transaction application involves careful consideration of synchronization, locking mechanisms, and data consistency.

• Identify critical sections of code that need to be synchronized to prevent race conditions

• Use synchronization mechanisms such as locks, semaphores, or atomic operations to ensure mutual exclusion

• Consider using transactional memory or software transactional memory for managing concurrent transactions

• Implement data structures tha...read more

The grazing area of the horse can be calculated by finding the area of the circle formed by the rope.

• Calculate the radius of the circle formed by the rope (15m).

• Use the formula for the area of a circle (A = πr^2) to find the grazing area.

• Subtract the area of the square (5cm x 5cm) from the grazing area to get the final result.

Design and print all nodes of a binary tree.

• Design a binary tree structure with left and right child pointers for each node.

• Implement a recursive function to print all nodes of the binary tree.

• Start from the root node and recursively print the left subtree, then the root, and finally the right subtree.

Design a system to find the millionth person liking a particular comment.

• Use a database to store the likes for each comment

• Implement a counter to keep track of the number of likes for each comment

• Use a caching mechanism to improve performance

• Consider sharding or partitioning the data for scalability

• Implement a search algorithm to find the millionth person

The question asks for the length of the longest absolute directory path string and how to optimize it.

• Use a depth-first search (DFS) algorithm to traverse the directory structure

• Maintain a stack to keep track of the current path length

• Keep updating the maximum path length encountered

• Consider the length of each directory/file name and the length of the path separators

Thrashing in an operating system occurs when the system is spending more time swapping data between memory and disk than actually executing tasks.

• Occurs when the system is overwhelmed with too many processes demanding memory

• Results in excessive swapping of data between RAM and disk

• Leads to a decrease in system performance as CPU spends more time on swapping than executing tasks

• Can be alleviated by optimizing memory usage or adding more physical memory

• Example: A system running...read more

1+√2 is greater than √5 graphically.

• Plot the points on a number line or graph.

• 1+√2 is approximately 2.41, while √5 is approximately 2.24.

• Therefore, 1+√2 is greater than √5.

Terraform state in file system can be managed using remote backends or local state files.

• Use remote backends like S3, Azure Blob Storage, or Google Cloud Storage for better collaboration and security.

• If using local state files, store them in a version-controlled directory to track changes and prevent conflicts.

• Consider using Terraform Cloud for centralized state management and collaboration among team members.

TCP is a connection-oriented protocol that provides reliable data delivery, while UDP is a connectionless protocol that offers faster but less reliable data transmission.

• TCP is reliable as it ensures all data packets are received in order and retransmits any lost packets.

• UDP is faster as it does not establish a connection before sending data and does not guarantee delivery of packets.

• TCP is used for applications that require high reliability and accuracy, such as web browsing...read more

CMS and G1 are Java garbage collectors with distinct internal processes for memory management.

• CMS (Concurrent Mark-Sweep) uses a concurrent approach to minimize pause times, focusing on marking live objects while the application is running.

• G1 (Garbage-First) divides the heap into regions and prioritizes garbage collection based on the amount of reclaimable space, aiming for predictable pause times.

• In CMS, the process includes initial marking, concurrent marking, and sweeping ...read more

The JVM memory model defines how memory is organized, accessed, and managed in Java applications.

• Memory is divided into several regions: Heap, Stack, Method Area, and others.

• Heap: Used for dynamic memory allocation for Java objects.

• Stack: Stores method frames, local variables, and partial results.

• Method Area: Holds class structures like metadata, constant pool, and static variables.

• Garbage Collection: Automatic memory management to reclaim memory from unused objects.

A scheduler is a function that manages the execution of tasks or processes.

• Inputs: tasks or processes to be scheduled, priority or order of execution

• Output: schedule or order in which tasks or processes will be executed

• Functioning: determines the order of execution based on predefined criteria or algorithms

A virtual destructor is a destructor declared as virtual in a base class to ensure proper destruction of derived class objects.

• Virtual destructors are used in polymorphic base classes to ensure that the destructor of the derived class is called when deleting a base class pointer.

• They allow proper cleanup of resources allocated in the derived class.

• Example: class Base { virtual ~Base() {} }; class Derived : public Base { virtual ~Derived() {} };

• Deleting a Base pointer pointing...read more

A copy constructor is a special type of constructor in C++ that creates a new object as a copy of an existing object.

• Copy constructor is used to initialize a new object as a copy of an existing object.

• It is invoked when an object is passed by value, returned by value, or explicitly called.

• Example: class MyClass { public: MyClass(const MyClass& obj) { // copy constructor logic } };

• Example: MyClass obj1; MyClass obj2 = obj1; // copy constructor is invoked to create obj2 as a co...read more

Yes, the standard requirements of risk management for medical devices include ISO 14971 and FDA regulations.

• ISO 14971 is an international standard for risk management of medical devices.

• FDA regulations require medical device manufacturers to establish and maintain a risk management process.

• Risk management for medical devices involves identifying hazards, estimating risks, and implementing controls to mitigate risks.

• Examples of risk management activities include risk assessmen...read more

Decoupling a monolith involves breaking it into smaller, independent services for better scalability and maintainability.

• Identify bounded contexts: Analyze the monolith to find distinct areas of functionality that can be separated.

• Use APIs for communication: Implement RESTful APIs or gRPC for services to interact without tight coupling.

• Adopt event-driven architecture: Utilize message brokers (e.g., RabbitMQ, Kafka) to enable asynchronous communication between services.

• Impleme...read more

Asynchronous in JS means executing code without blocking the main thread.

• Asynchronous code allows other code to run while waiting for a task to complete.

• It is commonly used for network requests, file I/O, and other time-consuming operations.

• Callbacks, Promises, and Async/Await are common ways to handle asynchronous code in JS.

To create an image out of a running container, you can use the 'docker commit' command.

• Use 'docker commit' command to create an image from a running container

• Syntax: docker commit [OPTIONS] CONTAINER [REPOSITORY[:TAG]]

• Example: docker commit container_id repository_name:tag

Key components and considerations for low-level design in a healthcare system

• Identifying the different modules and components of the system such as patient management, appointment scheduling, billing, etc.

• Defining the interactions between these components and how data flows between them

• Ensuring data security and privacy measures are in place to protect sensitive patient information

• Optimizing performance and scalability to handle a large volume of data and users

• Implementing fa...read more

CQI plays a crucial role in downlink MCS selection.

• CQI stands for Channel Quality Indicator.

• It is a measurement of the quality of the wireless channel between the base station and the user equipment.

• Based on the CQI, the base station determines the appropriate modulation and coding scheme (MCS) for downlink transmission.

• Higher CQI values indicate better channel conditions and allow for higher MCS with higher data rates.

• Lower CQI values indicate poorer channel conditions and r...read more

Dynamic Programming (DP) uses brute force and memoization to optimize recursive solutions for complex problems.

• Brute Force: Solve the problem by exploring all possible solutions, which can be inefficient.

• Memoization: Store results of expensive function calls and reuse them when the same inputs occur again.

• Example: Fibonacci sequence can be computed using brute force (exponential time) or memoization (linear time).

• DP is often used in problems like knapsack, longest common subs...read more

Detecting a loop in a linked list can be efficiently done using Floyd's Cycle-Finding Algorithm.

• Use two pointers: slow and fast. Initialize both at the head of the list.

• Move slow pointer one step at a time and fast pointer two steps at a time.

• If there is a loop, the fast pointer will eventually meet the slow pointer.

• If the fast pointer reaches the end of the list (null), there is no loop.

• Example: In a list 1 -> 2 -> 3 -> 4 -> 2 (loop back to 2), slow and fast will meet at 2.

Thrashing occurs when an OS spends more time swapping pages in and out of memory than executing processes.

• Thrashing happens when there is insufficient physical memory to hold all active processes.

• It leads to a significant decrease in system performance due to excessive paging.

• Example: A system running multiple memory-intensive applications may thrash if RAM is insufficient.

• To mitigate thrashing, the OS may implement page replacement algorithms or increase physical memory.

Develop and implement security and cloud controls for Cloud Engineering

• Conduct a thorough risk assessment to identify potential security threats

• Implement encryption protocols to protect data in transit and at rest

• Utilize multi-factor authentication to enhance access control

• Regularly monitor and audit cloud infrastructure for security vulnerabilities

• Implement automated security controls to quickly respond to threats

• Train employees on security best practices to prevent human er...read more

Use stack data structure to efficiently check validity of brackets in a string.

• Create an empty stack

• Traverse the string character by character

• If the character is an opening bracket, push it onto the stack

• If the character is a closing bracket, check if it matches the top of the stack

• If it matches, pop the top element from the stack

• If it doesn't match or the stack is empty, return false

• After traversing the entire string, if the stack is empty, return true

• Otherwise, return false

Given 2 arrays, one with n elements and another with n-1 elements, answer the question.

• Compare the elements of both arrays to find the missing element.

• Use a loop or a built-in function to iterate through the arrays.

• Consider edge cases where the missing element is at the beginning or end of the array.