Project Euler > Problem 146 > Investigating a Prime Pattern (Java Solution)

Problem:

The smallest positive integer n for which the numbers n2+1, n2+3, n2+7, n2+9, n2+13, and n2+27 are consecutive primes is 10. The sum of all such integers n below one-million is 1242490.

What is the sum of all such integers n below 150 million?


Solution:

5777

Code:
The solution may include methods that will be found here: Library.java .

public interface EulerSolution{

public String run();

}
/* 
* Solution to Project Euler problem 46
* By Nayuki Minase
*
* http://nayuki.eigenstate.org/page/project-euler-solutions
* https://github.com/nayuki/Project-Euler-solutions
*/


public final class p046 implements EulerSolution {

public static void main(String[] args) {
System.out.println(new p046().run());
}


public String run() {
for (int i = 2; ; i++) {
if (!satisfiesConjecture(i))
return Integer.toString(i);
}
}


private boolean satisfiesConjecture(int n) {
if (n % 2 == 0 || isPrime(n))
return true;

// Now n is an odd composite number
for (int i = 1; i * i * 2 <= n; i++) {
if (isPrime(n - i * i * 2))
return true;
}
return false;
}


private boolean[] isPrime = {};

private boolean isPrime(int n) {
if (n >= isPrime.length)
isPrime = Library.listPrimality(n * 2);
return isPrime[n];
}

}


No comments :

Post a Comment

Follow Me

If you like our content, feel free to follow me to stay updated.

Subscribe

Enter your email address:

We hate spam as much as you do.

Upload Material

Got an exam, project, tutorial video, exercise, solutions, unsolved problem, question, solution manual? We are open to any coding material. Why not upload?

Upload

Copyright © 2012 - 2014 Java Problems  --  About  --  Attribution  --  Privacy Policy  --  Terms of Use  --  Contact