Notes on Coding Interview Concepts and Problems

Jul 30, 2024

Coding Interview Questions Lecture Notes

Introduction

  • Discussion on coding interview questions.
  • Focus on data structures and algorithms.
  • Aim: Prepare for coding interviews with top questions.
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Agenda Overview

  • Part 1: Conceptual interview questions
  • Part 2: Common coding problems

Conceptual Interview Questions

What is a Data Structure?

  • Definition: A storage format defining data storage, organization, and manipulation.
  • Common types: Arrays, trees, graphs.

Arrays

  • Stores items of the same data type.
  • Organizes data for easy sorting/searching.

Linked Lists

  • Similar to arrays, but elements are not stored contiguously.
  • Composed of a sequence of nodes, each pointing to the next.

Stacks

  • Linear data structure.
  • Operates in LIFO (Last In, First Out) order.

LIFO

  • Last data stored is the first to be retrieved.

Queues

  • Linear data structure.
  • Operates in FIFO (First In, First Out) order.

FIFO

  • First data stored is the first to be retrieved.

Binary Trees

  • Extends linked list, each node has two children (left and right).

Recursion

  • A function calling itself based on a terminating condition.
  • Utilizes stack data structure.

Object-Oriented Programming System (OOPS)

  • Concepts: Objects, Classes, Inheritance, Polymorphism, Abstraction, Encapsulation.

OOPS Concepts Explained:

  1. Object: Real-world entity with state and behavior.
  2. Class: Blueprint from which objects are created.
  3. Inheritance: Ability to acquire properties/behaviors from parent object (code reusability).
  4. Polymorphism: Ability to perform tasks in different ways (method overloading/overriding in Java).
  5. Abstraction: Hides internal details, shows functionality (through abstract classes and interfaces).
  6. Encapsulation: Bundling of data and methods into a single unit.

Binary Search Tree

  • Stores data for efficient retrieval.
  • Left subtree: Nodes with keys < parent node's key.
  • Right subtree: Nodes with keys >= parent node's key.

Doubly Linked Lists

  • Linked list that allows traversal in both directions.

Graphs

  • Data structure containing ordered pairs (edges/arcs connecting nodes).

Linear vs Non-linear Data Structures

  • Linear:Adjacent data elements (e.g., arrays, linked lists, stacks, queues).
  • Non-linear: Elements connect to two or more others (e.g., trees, graphs).

Double-ended Queue (DQ)

  • Elements can be added/removed from either end.

Stack vs Array

  • Stack: Follows LIFO.
  • Array: Accessed by indexed elements, no specific order.

Sorting Algorithms

  • Examples: Quick sort, bubble sort, radix sort, merge sort.
  • No single best algorithm; each is optimized for specific data types.

Memory Allocation

  • Depends on variable data type (e.g., int = 32 bits).

Dynamic Data Structures

  • Expand/contract as the program runs, offering flexibility.

Programming Interview Questions

Common Coding Problems

  1. Reverse a string in Java.
  2. Determine if a string is a palindrome.
  3. Find occurrences of a character in a string.
  4. Check if two strings are anagrams.
  5. Count vowels and consonants in a string.
  6. Find matching elements in an integer array.
  7. Bubble sort algorithm.
  8. Insertion sort algorithm.
  9. Reverse an array.
  10. Swap two numbers without a third variable.
  11. Print Fibonacci series using recursion.
  12. Find the factorial of an integer.
  13. Reverse a linked list.
  14. Implement binary search.
  15. Find the second largest number in an array.
  16. Remove all occurrences of a character from a string.
  17. Show inheritance with a program.
  18. Explain overloading and overriding with code.
  19. Check if a given number is prime.
  20. Sum all elements in an array.

Conclusion

  • The discussed questions help prepare for coding interviews.
  • Open for questions in the comment section.
  • Encouraged to continue learning!