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86 lines
2.0 KiB
Java
86 lines
2.0 KiB
Java
/*
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This is a Java Program to Implement Pollard Rho Algorithm. Pollard Rho algorithm is a general purpose factorization algorithm. It is particularly effective at splitting composite numbers with small factors.
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*/
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/**
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** Java Program to implement Pollard Rho Algorithm
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**/
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import java.util.Scanner;
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/** Class PollardRho **/
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public class PollardRho
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{
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private static final long C = 1;
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/** function X * X + C, change value of C as required **/
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private long f(long X)
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{
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return X * X + C;
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}
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/** get divisor **/
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private long rho(long N)
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{
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long x1 = 2, x2 = 2, divisor;
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if (N % 2 == 0)
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return 2;
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do
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{
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x1 = f(x1) % N;
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x2 = f(f(x2)) % N;
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divisor = gcd(Math.abs(x1 - x2), N);
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}
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while (divisor == 1);
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/** return divisor **/
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return divisor;
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}
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/** GCD of two numbers **/
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public long gcd(long p, long q)
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{
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if (p % q == 0)
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return q;
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return gcd(q, p % q);
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}
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/** Check if num is prime **/
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public boolean isPrime(long N)
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{
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for (int i = 2; i <= Math.sqrt(N); i++)
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if (N % i == 0)
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return false;
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return true;
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}
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/** get all factors **/
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public void factor(long N)
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{
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if (N == 1)
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return;
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if (isPrime(N))
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{
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System.out.println(N);
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return;
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}
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long divisor = rho(N);
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factor(divisor);
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factor(N / divisor);
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}
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/** Main function **/
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public static void main(String[] args)
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{
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Scanner scan = new Scanner(System.in);
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System.out.println("Pollard Rho Algorithm\n");
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System.out.println("Enter a number");
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long N = scan.nextLong();
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System.out.println("\nFactors are : ");
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PollardRho pr = new PollardRho();
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pr.factor (N);
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}
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}
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/*
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Enter a number
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2406
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Factors are :
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2
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3
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401
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