Porter Senior Business Analyst Interview Questions and Answers

An immutable class is a class whose instances cannot be modified after creation.

• Make all fields private and final

• Don't provide any setter methods

• Ensure that any mutable objects passed to the constructor are defensively copied

• Make the class final so that it cannot be subclassed

Singleton pattern ensures only one instance of a class is created and provides a global point of access to it.

• Create a private constructor to prevent direct instantiation of the class.

• Create a private static instance of the class.

• Create a public static method to access the instance, and create the instance if it doesn't exist.

• Ensure thread safety by using synchronized keyword or double-checked locking.

Vector is synchronized and ArrayList is not. Vector is thread-safe and ArrayList is not.

• Vector is a legacy class and ArrayList is a part of the Java Collection Framework.

• Vector is synchronized which means only one thread can access it at a time, while ArrayList is not.

• Vector is thread-safe which means it can be used in a multi-threaded environment, while ArrayList is not.

• Vector is slower than ArrayList because of synch...read more

Create Linked List without using internal library and provide add, delete, find functionality.

• Create a Node class with data and next pointer

• Create a LinkedList class with head pointer and methods to add, delete, and find nodes

• Use a loop to traverse the list and perform operations

• Handle edge cases such as adding to an empty list or deleting the head node

The current system follows a microservices architecture.

• The system 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 microservices used in the system include user authentication, payment processing, and inventory management.

Find the total no of islands in a 2D matrix.

• Use DFS or BFS to traverse the matrix.

• Mark visited cells to avoid repetition.

• Count the number of islands found.

Loop detection in a linked list.

• Use two pointers, one moving at twice the speed of the other.

• If there is a loop, the faster pointer will eventually catch up to the slower one.

• If there is no loop, the faster pointer will reach the end of the list.

The weight of an aircraft is crucial for its performance and safety.

• The weight of an aircraft includes the weight of the aircraft itself, fuel, passengers, cargo, and any other equipment on board.

• The weight of an aircraft is measured in pounds or kilograms.

• The weight of an aircraft affects its takeoff and landing performance, as well as its fuel efficiency and range.

• Aircraft manufacturers provide maximum takeoff and la...read more

SQL query to get top 100 Uber drivers by city

• Join drivers and users tables on city

• Aggregate driver ratings and count of rides

• Order by rating and count of rides

• Limit to top 100

Optimizing the listing of Restaurants on Swiggy involves using data-driven strategies to improve visibility, relevance, and user experience.

• Analyze user behavior and preferences to understand their needs and preferences

• Implement a ranking algorithm based on factors like ratings, reviews, popularity, and delivery time

• Optimize search functionality to ensure accurate and relevant results

• Collaborate with restaurants to imp...read more

Linear Regression is used for continuous data while Logistic Regression is used for categorical data.

• Linear Regression predicts continuous values while Logistic Regression predicts probabilities.

• Linear Regression uses a straight line to fit the data while Logistic Regression uses an S-shaped curve.

• Linear Regression uses Mean Squared Error as the cost function while Logistic Regression uses Log Loss.

• Linear Regression is...read more

Bias-Variance trade-off is the balance between overfitting and underfitting. High bias models are simple but inaccurate, low variance models are complex but overfit.

• Bias-Variance trade-off is a fundamental concept in machine learning.

• High bias models are simple and have low variance, but are inaccurate.

• Low bias models are complex and have high variance, but can overfit the data.

• Examples of high bias models are linear r...read more

Possible reasons for a car manufacturer's decline in profits by 40% year over year

• Decreased demand for cars due to economic downturn

• Increased competition from other car manufacturers

• Rising production costs and expenses

• Decline in consumer confidence and spending

• Changes in government regulations impacting the automotive industry