ThoughtWorks Application Developer Interview Questions and Answers

Reversing a linked list involves changing the direction of its pointers to reverse the order of nodes.

• Iterative approach: Use three pointers (prev, current, next) to reverse links.

• Example: For list 1 -> 2 -> 3, after reversal it becomes 3 -> 2 -> 1.

• Recursive approach: Reverse the rest of the list and adjust pointers.

• Example: Recursively reverse 1 -> 2 -> 3, then link 2 to 1 and 3 to 2.

HashMap in Java is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values.

• HashMap uses hashing to store and retrieve key-value pairs

• It uses an array of linked lists to handle collisions

• The key's hash code is used to determine the index in the array where the key-value pair is stored

• HashMap allows one null key and multiple null values

• Example: HashMap<String, Integer> map ...read more

The Two Sum problem involves finding two numbers in an array that add up to a specific target sum.

• Given an array of integers and a target sum, identify two numbers that sum to the target.

• Example: For array [2, 7, 11, 15] and target 9, the answer is indices 0 and 1 (2 + 7 = 9).

• Use a hash map to store numbers and their indices for efficient lookup.

• Time complexity can be O(n) with a hash map, compared to O(n^2) with ...read more

Multithreading allows multiple threads to execute concurrently within a single process.

• Multithreading allows for parallel execution of tasks within a single process.

• Each thread has its own stack and runs independently of other threads.

• Threads share the same memory space, allowing for communication and data sharing.

• Multithreading can improve performance by utilizing multiple CPU cores efficiently.

• Examples of multit...read more

HTTP is a protocol used for transferring data over the internet.

• HTTP stands for Hypertext Transfer Protocol.

• It is the foundation of data communication on the World Wide Web.

• HTTP works by establishing a connection between a client and a server, where the client sends a request and the server responds with the requested data.

• HTTP uses methods like GET, POST, PUT, DELETE to specify the action to be performed on a res...read more

HashMap is a data structure commonly used in backend development for efficient key-value storage and retrieval.

• HashMap is a collection that stores key-value pairs and allows for fast retrieval of values based on keys.

• It is commonly used in backend development for caching, session management, and data storage.

• Example: HashMap<String, Integer> employeeSalaries = new HashMap<>(); employeeSalaries.put("Ali...read more

Choosing the right technology stack is crucial for project success, impacting performance, scalability, and maintainability.

• Technology selection should align with project requirements and team expertise.

• For web applications, using React for the frontend and Node.js for the backend can enhance performance and developer productivity.

• In mobile app development, Flutter allows for cross-platform development, reducing t...read more