Project Euler > Problem 35 > Circular primes (Java Solution)

Problem:

The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime.

There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, and 97.

How many circular primes are there below one million?

Solution:

55

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

public interface EulerSolution{

public String run();

}

/* 
 * Solution to Project Euler problem 35
 * By Nayuki Minase
 * 
 * http://nayuki.eigenstate.org/page/project-euler-solutions
 * https://github.com/nayuki/Project-Euler-solutions
 */


public final class p035 implements EulerSolution {
 
 public static void main(String[] args) {
  System.out.println(new p035().run());
 }
 
 
 private static final int LIMIT = Library.pow(10, 6);
 
 private boolean[] isPrime = Library.listPrimality(LIMIT - 1);
 
 
 public String run() {
  int count = 0;
  for (int i = 0; i < isPrime.length; i++) {
   if (isCircularPrime(i))
    count++;
  }
  return Integer.toString(count);
 }
 
 
 private boolean isCircularPrime(int n) {
  String s = Integer.toString(n);
  for (int i = 0; i < s.length(); i++) {
   if (!isPrime[Integer.parseInt(s.substring(i) + s.substring(0, i))])
    return false;
  }
  return true;
 }
 
}