We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
Loading...
  1. Practice
  2. Java
  3. Advanced
  4. Prime Checker
  5. Discussions

Prime Checker

  • wzrds3 + 0 comments

    Since the locked code involves repeat checks of primailty, I factored in some caching so the code doesn't have to repeatedly check values.

    class Prime{
    private static Set<Integer> prime_list = new HashSet<>();

    public void checkPrime(int ... nums) {
        for (int num : nums) {
            if (prime_list.contains(num)) {
                System.out.print(num + " ");
            } else if (isPrime(num)) {
                prime_list.add(num);
                System.out.print(num + " ");
            }
        }
        System.out.println();
    }

    private static boolean isPrime(int n) {
        if (n < 2) return false;
        else if (n < 4) return true;
        else if (n % 2 == 0) return false;
        
        int sqrt = (int) Math.sqrt(n);
        for (int i = 3; i <= sqrt; i += 2) {
            if (n % i == 0) return false;
        }
        return true;
    }
}