✅ Core Coding Interview Questions With Answers 🖥️

1 What is a programming language
- Formal language to write instructions for computers
- Translated to machine code via compiler or interpreter
- Examples: Python (interpreted), C++ (compiled)

2 What is a data structure
- Way to organize and store data for efficient access
- Rows/records in arrays, nodes in linked lists
- Example: Array stores customer names in sequence

3 What is an algorithm
- Step-by-step procedure to solve a problem
- Takes input, processes it, produces output
- Example: Steps to find max in array by scanning once

4 What is an array
- Fixed-size collection of same-type elements
- Accessed by index starting from 0
- Example: int ages[1] = {25, 30, 35}; ages[2] is 30

5 What is a linked list
- Collection of nodes with data and next pointer
- Dynamic size, no random access
- Example: Head → Node(25) → Node(30) → NULL

6 Difference between array and linked list
- Array: fixed size, fast access O(1), slow insert
- Linked list: dynamic size, slow access O(n), fast insert
- Use array for frequent reads, list for inserts

7 What is a stack
- LIFO (Last In First Out) structure
- Operations: push, pop, peek
- Example: Undo in editors uses stack

8 What is a queue
- FIFO (First In First Out) structure
- Operations: enqueue, dequeue
- Example: Printer jobs line up as queue

9 What are OOP principles
- Encapsulation, Inheritance, Polymorphism, Abstraction
- Bundle data/methods, reuse code, override behaviors
- Example: Base Animal class, Dog inherits and adds bark()

10 Interview tip you must remember
- Draw examples on whiteboard (array diagram)
- Explain time/space complexity first (O(n))
- Practice in C++, JS, Python for your stack

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