{"id":33898,"date":"2024-11-01T09:21:44","date_gmt":"2024-11-01T09:21:44","guid":{"rendered":"http:\/\/atmokpo.com\/w\/?p=33898"},"modified":"2024-11-01T10:55:22","modified_gmt":"2024-11-01T10:55:22","slug":"c-coding-test-course-finding-amazing-prime-numbers","status":"publish","type":"post","link":"https:\/\/atmokpo.com\/w\/33898\/","title":{"rendered":"C# Coding Test Course, Finding Amazing Prime Numbers"},"content":{"rendered":"

<\/p>\n

\n In today’s software development environment, coding tests have become an important factor.
\n Companies present various problems to assess candidates’ algorithmic thinking and problem-solving skills.
\n In this blog, we will solve a coding test problem on the topic of finding interesting prime numbers.\n <\/p>\n

Problem Description<\/h2>\n

\n Write a program to find and print all prime numbers less than or equal to the given integer N.
\n A prime number is a natural number that is divisible only by 1 and itself,
\n meaning it has no divisors other than 1 and itself among natural numbers greater than or equal to 2.\n <\/p>\n

Input<\/h3>\n

\n An integer N is given in the first line. (2 <= N <= 1000000)\n <\/p>\n

Output<\/h3>\n

\n Print all prime numbers less than or equal to N, one per line.\n <\/p>\n

Approach to the Problem<\/h2>\n

\n The most common method to find prime numbers is to use the Sieve of Eratosthenes.
\n This algorithm is efficient and can be used even when N is large.
\n Using the Sieve of Eratosthenes, prime numbers can be found in the following order:\n <\/p>\n

    \n
  1. List all numbers from 2 to N.<\/li>\n
  2. Starting from 2, remove all multiples of that number.<\/li>\n
  3. Select the smallest remaining number and remove its multiples in the same manner.<\/li>\n
  4. Repeat this process for numbers less than the square root of N.<\/li>\n
  5. All remaining numbers are prime.<\/li>\n<\/ol>\n

    C# Code Implementation<\/h2>\n

    \n Below is the C# code that implements the above algorithm:\n <\/p>\n

    \n        \n        using System;\n        using System.Collections.Generic;\n\n        class Program {\n            static void Main(string[] args) {\n                int N = int.Parse(Console.ReadLine());\n                bool[] isPrime = new bool[N + 1];\n                \n                for (int i = 2; i <= N; i++) {\n                    isPrime[i] = true; \/\/ Initialize all numbers as prime\n                }\n\n                for (int i = 2; i * i <= N; i++) {\n                    if (isPrime[i]) { \/\/ If i is prime\n                        for (int j = i * i; j <= N; j += i) {\n                            isPrime[j] = false; \/\/ Mark multiples of i as non-prime\n                        }\n                    }\n                }\n\n                for (int i = 2; i <= N; i++) {\n                    if (isPrime[i]) {\n                        Console.WriteLine(i); \/\/ Print prime numbers\n                    }\n                }\n            }\n        }\n        <\/code>\n    <\/pre>\n
    Code Explanation<\/h2>\n
    \n        The above code implements the Sieve of Eratosthenes algorithm using C#.
    \n        Let’s go through each line in detail.\n    <\/p>\n