🧠 Must-Solve DSA Problems

This repository contains a comprehensive collection of Java programs that cover the most essential Data Structures and Algorithms (DSA) problems — perfect for placements, coding interviews, and daily practice.

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📂 Folder Structure

1️⃣ Array-Basics-Problems

Covers foundational array problems like:

• Find the largest and smallest element
• Find the second largest element
• Check if an array is sorted
• Reverse an array (in-place)
• Find the missing number (1 to N)
• Remove duplicate elements
• Find all pairs with a given sum
• Left rotate the array by one position
• Count frequency of each element
• Merge two sorted arrays

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2️⃣ String-Basics-Problems

Includes string manipulation challenges:

• Toggle case of characters
• Reverse a string
• Check if a string is palindrome
• Count vowels and consonants
• Remove all whitespaces
• Remove duplicate characters
• Find the first non-repeating character
• Check if two strings are anagrams
• Capitalize first letter of each word
• Count the frequency of characters

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3️⃣ Pattern & Number Logic Problems

Practice logical pattern and number-based programs:

• Right-angled triangle of stars
• Inverted right-angled triangle
• Right-aligned triangle
• Pyramid pattern
• Number triangle
• Floyd’s triangle
• Multiplication table of a number
• Sum of first N natural numbers
• Reverse a number
• Print all even numbers up to N

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4️⃣ Recursion Problems

Learn and master recursion through:

• Print numbers from 1 to N and N to 1
• Find factorial of a number
• Calculate sum of digits
• Reverse a string
• Check if a string or number is palindrome
• Generate Fibonacci sequence
• Calculate power of a number
• Find GCD using recursion
• Count digits in a number
• Find the Nth Fibonacci number

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5️⃣ Most Commonly Asked Problems

Essential programs often asked in interviews:

• Check if a number is prime
• Find factorial of a number
• Count prime numbers between two numbers
• Sum of digits in a number
• Find GCD of two numbers
• Check Armstrong number
• Reverse a number
• Generate Fibonacci series up to N terms
• Check odd or even
• Find the largest of three numbers

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🚀 Features

• ✅ Beginner-friendly structured problems
• ✅ Clean and readable Java code
• ✅ Organized folder-wise by topic
• ✅ Useful for placement and coding interview prep
• ✅ Ideal for practicing logic building and recursion

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📘 Author

👨‍💻 Ganesh Moorthi M
B.E. Computer Science and Engineering | Einstein College of Engineering

💡 Passionate about problem-solving, web development, and mastering DSA concepts.

📫 Connect on GitHub: Ganeshmoorthii