10+ Product Development Engineer Interview Questions and Answers

Calculate the total amount of rainwater that can be trapped within given elevation map.

• Iterate through the array to find the maximum height on the left and right of each bar.

• Calculate the amount of water that can be trapped above each bar by taking the minimum of the maximum heights on the left and right.

• Sum up the trapped water above each bar to get the total trapped water for the elevation map.

Use two pointers to swap 0s to the beginning and 2s to the end while keeping 1s in the middle.

• Initialize two pointers, one for 0s (left) and one for 2s (right).

• Iterate through the array and swap 0s to the left pointer and 2s to the right pointer.

• Example: Input array = ['2', '1', '0', '2', '1', '0'], Output array = ['0', '0', '1', '1', '2', '2']

Find the first character that repeats in a given string.

• Iterate through the string and keep track of characters seen so far.

• If a character is already seen, return it as the first repeating character.

• If no repeating character is found, return null.

Async and threading offer advantages in improving performance and responsiveness in software development.

• Async allows for non-blocking operations, improving responsiveness by allowing other tasks to continue while waiting for a response.

• Threading enables parallel execution of tasks, utilizing multiple CPU cores to improve performance.

• Async is more suitable for I/O-bound operations, while threading is better for CPU-bound tasks.

• Combining async and threading can maximize perfor...read more

Developing a smart waste management system to optimize recycling and reduce landfill waste in urban areas.

• Implement IoT sensors in waste bins to monitor fill levels and types of waste.

• Use data analytics to optimize collection routes and schedules based on real-time data.

• Create a mobile app for residents to report overflowing bins and track recycling efforts.

• Partner with local recycling facilities to ensure proper waste processing and education.

To swap numbers without using a third variable, use arithmetic operations.

• Add the two numbers to get the first number

• Subtract the second number from the sum to get the second number

• Subtract the original first number from the sum to get the original second number

Use Twitter's public API to extract trending hashtags.

• Authenticate with Twitter API using OAuth 1.0a

• Make a GET request to the trends/place endpoint

• Extract the hashtags from the response and return as an array of strings

Global Interpreter Lock (GIL) is a mutex that protects access to Python objects, preventing multiple threads from executing Python bytecodes simultaneously.

• GIL is a mechanism used in CPython to ensure that only one thread executes Python bytecode at a time.

• It prevents multiple threads from executing Python code concurrently, which can cause issues with thread safety.

• GIL can impact the performance of multi-threaded Python programs, as only one thread can execute Python code at...read more

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

• Use a hashmap to store the difference between the target and each element as keys and their indices as values.

• Iterate through the array and check if the current element's complement exists in the hashmap.

• Return the indices of the two numbers that add up to the target.

OOPs concepts like encapsulation, inheritance, polymorphism, and abstraction enhance software design and reusability.

• Encapsulation: A class 'Car' can encapsulate properties like 'speed' and 'fuel' with methods to manipulate them.

• Inheritance: A 'ElectricCar' class can inherit from the 'Car' class, gaining its properties and methods while adding new features.

• Polymorphism: A method 'startEngine()' can behave differently for 'Car' and 'Motorcycle' classes, showcasing method overr...read more

My favorite subjects in mechanical engineering are thermodynamics, fluid mechanics, and materials science.

• Thermodynamics: Study of energy and heat transfer in mechanical systems. Example: analyzing the efficiency of an engine.

• Fluid mechanics: Study of fluids in motion and at rest. Example: designing a pump system for a manufacturing plant.

• Materials science: Study of properties and behavior of materials. Example: selecting the right material for a specific application.

A starter motor is an electric motor used to start an internal combustion engine.

• Used to crank the engine to start it

• Powered by the vehicle's battery

• Engages with the flywheel or flexplate to turn the engine over

• Commonly found in automobiles and other vehicles

DBMS locking is a mechanism to manage concurrent access to data in a database to prevent data corruption.

• Locking is used to ensure data integrity and consistency in a multi-user environment.

• Types of locks include shared locks, exclusive locks, and update locks.

• Example scenario: Two users trying to update the same record simultaneously - one user gets an exclusive lock while the other waits.

• Deadlocks can occur when two transactions are waiting for each other to release locks.

A queue can be implemented using arrays or linked lists. It follows the FIFO principle.

• Create an empty array or linked list

• Enqueue elements at the end of the queue

• Dequeue elements from the front of the queue

• Implement methods like isEmpty, isFull, peek, etc.

• Example: Queue implemented using an array - https://www.geeksforgeeks.org/queue-set-1introduction-and-array-implementation/

LRU cache program is a data structure that stores the most recently used items.

• LRU cache is typically implemented using a doubly linked list and a hashmap.

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

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

• Example: If the cache has a capacity of 3 and items A, B, C are accessed in that order, the cache will store C, B, A.

• Example: If item B is accessed again, it will move to t...read more