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Important technical interview questions


  1. What is a Data Structure?
    A way to organize and store data so it can be accessed and modified efficiently, such as arrays, lists, trees, and graphs.

  2. Explain Big-O Notation.
    A way to describe the efficiency of an algorithm, showing how its running time or space usage grows as input size increases.

  3. What is Recursion?
    When a function calls itself to solve a smaller version of a problem until reaching a base case.

  4. Explain Object-Oriented Programming (OOP).
    A programming style based on objects that contain data (attributes) and code (methods), using concepts like inheritance, encapsulation, and polymorphism.

  5. What is a Linked List?
    A linear collection of elements called nodes where each node points to the next, allowing dynamic memory allocation.

  6. How does Binary Search work?
    A search technique that finds an element efficiently by repeatedly dividing a sorted list in half.

  7. What are Stacks and Queues?
    Stacks follow Last-In-First-Out (LIFO) order, like a stack of plates; queues follow First-In-First-Out (FIFO), like a line of people.

  8. Explain Hash Tables.
    Data structures that store key-value pairs with fast data retrieval using a hash function.

  9. What is a Deadlock in a system?
    A situation where two or more processes wait indefinitely for resources held by each other, causing a standstill.

  10. Describe System Design basics.
    How to architect systems for scalability and reliability, including concepts like load balancing, caching, databases, and microservices.