Code:
/**
** Java Program to Implement Miller Rabin Primality Test Algorithm
**/
import java.util.Scanner;
import java.util.Random;
import java.math.BigInteger;
/** Class MillerRabin **/
public class MillerRabin
{
/** Function to check if prime or not **/
public boolean isPrime(long n, int iteration)
{
/** base case **/
if (n == 0 || n == 1)
return false;
/** base case - 2 is prime **/
if (n == 2)
return true;
/** an even number other than 2 is composite **/
if (n % 2 == 0)
return false;
long s = n - 1;
while (s % 2 == 0)
s /= 2;
Random rand = new Random();
for (int i = 0; i < iteration; i++)
{
long r = Math.abs(rand.nextLong());
long a = r % (n - 1) + 1, temp = s;
long mod = modPow(a, temp, n);
while (temp != n - 1 && mod != 1 && mod != n - 1)
{
mod = mulMod(mod, mod, n);
temp *= 2;
}
if (mod != n - 1 && temp % 2 == 0)
return false;
}
return true;
}
/** Function to calculate (a ^ b) % c **/
public long modPow(long a, long b, long c)
{
long res = 1;
for (int i = 0; i < b; i++)
{
res *= a;
res %= c;
}
return res % c;
}
/** Function to calculate (a * b) % c **/
public long mulMod(long a, long b, long mod)
{
return BigInteger.valueOf(a).multiply(BigInteger.valueOf(b)).mod(BigInteger.valueOf(mod)).longValue();
}
/** Main function **/
public static void main (String[] args)
{
Scanner scan = new Scanner(System.in);
System.out.println("Miller Rabin Primality Algorithm Test\n");
/** Make an object of MillerRabin class **/
MillerRabin mr = new MillerRabin();
/** Accept number **/
System.out.println("Enter number\n");
long num = scan.nextLong();
/** Accept number of iterations **/
System.out.println("\nEnter number of iterations");
int k = scan.nextInt();
/** check if prime **/
boolean prime = mr.isPrime(num, k);
if (prime)
System.out.println("\n"+ num +" is prime");
else
System.out.println("\n"+ num +" is composite");
}
}
Output:
Miller Rabin Primality Algorithm Test
Enter number
5510389
Enter number of iterations
2
5510389 is prime
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