A Curated Repository of Early C# Algorithms for Technical Interviews

Collection of Basic C# Algorithms is a focused, practical repository designed to assist developers — particularly junior and mid-level professionals — in preparing for technical interviews that involve algorithmic problem-solving in C#. This collection emerged from personal experience and professional necessity. It serves as a foundational resource for those who may not have received formal training in data structures and algorithms, yet frequently encounter algorithmic challenges during interviews for roles that do not require algorithmic problem-solving as part of day-to-day responsibilities. These are not optimal solutions, but solutions optimized for beginners who may find it easy to think in simpler, yet more verbose terms. Motivation and Purpose The motivation behind this repository was twofold: To reduce signal noise: Developers preparing for interviews often face an overwhelming volume of information, with algorithm repositories offering hundreds of problems of varying relevance or complexity. This project aims to distill the essentials — the most frequently asked, straightforward algorithmic questions — and present them clearly in C#. To support self-taught developers: Many developers come to the field through nontraditional paths. This repository provides them with an accessible point of entry into algorithmic thinking, aligned with industry expectations. Target Audience Junior to mid-level developers preparing for interviews Developers transitioning into more technical or algorithm-heavy roles Individuals without a computer science background seeking structured, minimal examples of classic problems Interviewees applying to companies that require a basic proficiency in algorithms without expecting advanced computer science knowledge Selected Examples Below are three representative algorithms from the repository. Each example demonstrates core algorithmic reasoning and is implemented in clear, idiomatic C#. 1. Reverse Words in a String public static void ReverseWordsinaString() { string input = "Hello World"; string[] words = input.Split(' '); Array.Reverse(words); string reversedString = string.Join(" ", words); Console.WriteLine(reversedString); } Use Case: Reverses the order of words in a given string (e.g., "hello world" becomes "world hello"). Concepts Reinforced: String splitting, array manipulation, and use of Array.Reverse. 2. Check if a String is a Palindrome public static void IsStringPalindrome() { string input = "racecar"; input = input.Replace(" ", "").ToLower(); string reversed = ReverseString(input); bool isPalindrome = input.Equals(reversed); if (isPalindrome) { Console.WriteLine("The string is a palindrome."); } else { Console.WriteLine("The string is not a palindrome."); } } // Helper method to reverse a string static string ReverseString(string s) { char[] charArray = s.ToCharArray(); Array.Reverse(charArray); return new string(charArray); } Use Case: Checks whether a string reads the same forwards and backwards. Concepts Reinforced: String normalization, helper methods, conditionals. 3. Checking for Prime Numbers public static void IsIntPrime() { int number = 17; // Replace with the positive integer you want to check bool isPrime = IsPrime(number); if (isPrime) { Console.WriteLine($"{number} is a prime number."); } else { Console.WriteLine($"{number} is not a prime number."); } } static bool IsPrime(int n) { if (n

public static void ReverseWordsinaString()
{
    string input = "Hello World";

    string[] words = input.Split(' ');

    Array.Reverse(words);

    string reversedString = string.Join(" ", words);

    Console.WriteLine(reversedString);
}

public static void IsStringPalindrome()
{
    string input = "racecar";

    input = input.Replace(" ", "").ToLower();

    string reversed = ReverseString(input);

    bool isPalindrome = input.Equals(reversed);

    if (isPalindrome)
    {
        Console.WriteLine("The string is a palindrome.");
    }
    else
    {
        Console.WriteLine("The string is not a palindrome.");
    }
}

// Helper method to reverse a string
static string ReverseString(string s)
{
    char[] charArray = s.ToCharArray();
    Array.Reverse(charArray);
    return new string(charArray);
}

public static void IsIntPrime()
{
    int number = 17; // Replace with the positive integer you want to check
    bool isPrime = IsPrime(number);

    if (isPrime)
    {
        Console.WriteLine($"{number} is a prime number.");
    }
    else
    {
        Console.WriteLine($"{number} is not a prime number.");
    }
}

static bool IsPrime(int n)
{
    if (n <= 1)
    {
        return false;
    }
    if (n <= 3)
    {
        return true;
    }
    if (n % 2 == 0 || n % 3 == 0)
    {
        return false;
    }

    for (int i = 5; i * i <= n; i += 6)
    {
        if (n % i == 0 || n % (i + 2) == 0)
        {
            return false;
        }
    }

    return true;
}