Check whether the sum of absolute difference of adjacent digits is Prime or not

// C# implementation of the above approach 
using System;
    
class GFG 
{

    // Function to check for a prime number
    static bool Prime(int n)
    {
        if (n == 1)
            return false;
        for (int i = 2; i * i <= n; i++)
            if (n % i == 0)
                return false;
        return true;
    }

    // Function to find the sum of array
    static bool checkSumPrime(String str)
    {
        int summ = 0;
        for (int i = 1; i < str.Length; i++)
            summ += Math.Abs(str[i - 1] -
                             str[i]);

        if (Prime(summ))
            return true;
        else
            return false;
    }

    // Driver Code
    public static void Main(String[] args)
    {
        String str = "142";
        if (checkSumPrime(str))
            Console.WriteLine("Prime");
        else
            Console.WriteLine("Not Prime");
    }
}

// This code is contributed by Rajput-Ji

using System;
using System.Text.RegularExpressions;

class GFG
{
    // Function to check if a number is prime
    public static bool IsPrime(int n)
    {
        if (n < 2)
        {
            return false;
        }
        for (int i = 2; i <= Math.Sqrt(n); i++)
        {
            if (n % i == 0)
            {
                return false;
            }
        }
        return true;
    }

    // Function to check if the sum of adjacent digits' 
   // differences is prime
    public static bool IsPrimeSumAdjacentDigits(int n)
    {
        // Convert the number to a string to extract individual digits
        string nString = n.ToString();
        // Use regular expression to find all individual digits
        MatchCollection matches = Regex.Matches(nString, @"\d");
        // Create an array to store the extracted digits
        int[] digits = new int[nString.Length];
        int i = 0;
        // Convert the matched digits back to integers and store 
       // them in the array
        foreach (Match match in matches)
        {
            digits[i++] = int.Parse(match.Value);
        }

        // Calculate the sum of absolute differences between 
       // adjacent digits
        int diffSum = 0;
        for (int j = 0; j < digits.Length - 1; j++)
        {
            diffSum += Math.Abs(digits[j] - digits[j + 1]);
        }

        // Check if the sum of differences is prime using 
       // the IsPrime function
        return IsPrime(diffSum);
    }

    public static void Main(string[] args)
    {
        int n = 142;
        // Check if the sum of adjacent digits' differences is
       // prime for the number 142
        if (IsPrimeSumAdjacentDigits(n))
        {
            Console.WriteLine("Prime");
        }
        else
        {
            Console.WriteLine("Not prime");
        }

        n = 347;
        // Check if the sum of adjacent digits' differences is 
       // prime for the number 347
        if (IsPrimeSumAdjacentDigits(n))
        {
            Console.WriteLine("Prime");
        }
        else
        {
            Console.WriteLine("Not prime");
        }
    }
}

using System;

public class Program {
    // Function to generate a sieve of Eratosthenes to find
    // prime numbers up to a given limit
    public static bool[] GenerateSieve(int limit)
    {
        bool[] sieve = new bool[limit + 1];
        Array.Fill(sieve, true);
        sieve[0] = sieve[1] = false;

        for (int p = 2; p <= (int)Math.Sqrt(limit); p++) {
            if (sieve[p]) {
                for (int i = p * p; i <= limit; i += p) {
                    sieve[i] = false;
                }
            }
        }

        return sieve;
    }

    // Function to check if a number is prime using the
    // sieve
    public static bool IsPrime(int n, bool[] sieve)
    {
        return sieve[n];
    }

    // Function to calculate the sum of absolute differences
    // between adjacent digits of a number
    public static int
    CalculateSumOfAbsoluteDifferences(int N)
    {
        int sum = 0;
        int prevDigit = N % 10;
        N /= 10;

        while (N > 0) {
            int currDigit = N % 10;
            sum += Math.Abs(currDigit - prevDigit);
            prevDigit = currDigit;
            N /= 10;
        }

        return sum;
    }

    // Function to check if a number is prime using the
    // sieve
    public static bool IsSumPrime(int sum, bool[] sieve)
    {
        return IsPrime(sum, sieve);
    }

    public static void Main(string[] args)
    {
        int N = 142;

        // Generate a sieve of primes up to the maximum
        // possible sum
        int maxSum = 9 * (int)(Math.Log10(N));
        bool[] sieve = GenerateSieve(maxSum);

        // Calculate the sum of absolute differences
        int sum = CalculateSumOfAbsoluteDifferences(N);

        // Check if the sum is prime or not
        bool isPrimeSum = IsSumPrime(sum, sieve);

        if (isPrimeSum) {
            Console.WriteLine("Prime");
        }
        else {
            Console.WriteLine("Not Prime");
        }
    }
}